Chapter_10 Recommended Practice for ESP Failure Analysis

Mohamed Dewidar 2013

Electric Submersible Pumps Chapter 10

Recommended Practice for ESP Dismantle, Inspection & Failure Analysis (DIFA) Table of Content Section

Content

Page

1.0

Purpose

2

2.0

Post Failure

3

3.0

Pre-Pulled Requirements

3

4.0

Pulling the ESP

4

Critical Pull Observation Disassembly of the ESP at well site

4 5

Dismantle, Inspection, & Failure Analysis (Difa) Preparation Cable Pumps BOI/GS Protector(s) Motor(s) Downhole Monitoring Device (Sensor)

10 10 11 11 16 17 21 26

Root Cause Analysis (RCA)

26

Difa Report Format Cover Table of Contents Distribution Well Information Trend Analysis ESP Identification information Dismantle Inspection Findings

28 28 29 29 29 29 30 30

4.1 4.2 5.0 5.1 5.2 5.3 5.4 5.5 5.6 5.7 6.0 7.0 7.1 7.2 7.3 7.4 7.5 7.6 7.7

7.8 Summary of Results 7.9 Recommendations 7.10 Photograph Gallery

30 30 30

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Recommended Practice for ESP Dismantle, Inspection & Failure Analysis (DIFA) Introduction This document outlines the “standard” for dismantle inspection and failure analysis (DIFA) of electric submersible pumps (ESPs). The local engineering manager shall authorize a DIFA for any pulled ESP equipment. The electric submersible pump vendor is responsible for conducting and producing the DIFA and DIFA report, respectively. However, significant portions of the required data must be provided by customer. Customer, and its affiliates, shall be a partner in reviewing and approving the DIFA and DIFA report.

11.1. Purpose The purpose of this standard is to determine the root cause of an ESP failure. Identification of this root cause should lead to operational and/or equipment modifications which ultimately result in improved runlife performance. It is imperative that the analysis commence prior to the pulling of the failed equipment. It is equally important that the DIFA recommended changes be implemented by customer, its affiliates and the vendor. All too often, maximizing run life is not accomplished because ESP failures are not properly identified. Many factors must be investigated and documented to determine the ultimate cause of failure. The first flaw discovered in the failure of an ESP system is often times given full responsibility for the failure. This identified method of analysis can result in a much shorter average run life in a given well and/or field. Maximizing run life of ESP's can be accomplished through proper analysis of failure modes and investigating all aspects of the ESP system. This process can take many hours and/or weeks, particularly if the field is being analyzed for the first time. It is important to note that when investigating a single failure, one must also take into account the entire field operation and procedures along with the complete history of ESP performance in that field. Customer personnel shall be responsible for the administration of this standard in the respective business units. Each manufacturer shall have a specific “DIFA Procedure” that meets, or exceeds, the requirements as outlined in this standard. Any variation from this standard must be approved by 2

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a customer representative analysis program.

prior

to

commencing

a

failure

11.2. Post Failure When the ESP equipment has failed, it is important that all relative information be captured. The following items, if available, shall be captured and quarantined for inclusion into the DIFA.  All motor controller/VSD operational data.  Amp charts, or amperage data.  Downhole monitoring data.  SCADA or life of well system, data (e.g. LOWIS, ESP Watcher, Wellview, Xspoc, etc.). This data shall include any surface processing equipment data that may be relevant.  Histories of choke settings inclusive of choke setting at time of failure.  Production data (oil, gas & water).  History of actions taken prior and after the shutdown (e.g. number of restart attempts, etc.)  Well ESP failure history (if available), previous DIFA reports from the same well.

inclusive

of

 Chemical treatment history.  Initial sizing and design reports  Installation reports  Any daily field reports that may detail sequence of events or equivalent

11.3. Pre-Pull Requirements Prior to pulling the equipment, all parties should be advised that the pulling of the failed equipment is an integral part of determining the cause of failure. Any unusual events, or items, should be captured as part of the pull report. All key electrical readings should be checked and recorded prior to commencing pulling operations. In addition to the standard items supplied by the service company for pulling ESP equipment, the following items are required to be available during pulling operations: 12 each, 1 pint, wide mouth, plastic sample bottles. 24 each, 1 quart, plastic bags (zip-lock type). 3

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Electric Submersible Pumps Chapter 10

36 each 2” x 6” cards to be used as identification markers in photographs. Permanent markers. Grease sticks (yellow or white) to circle/identify critical items. Digital camera to take pictures of any/all unique items. Pressure monitoring equipment (5-25 psi capability) – to check protector/seal shaft seals and ascertain if any pressure is between motor and lower protector/seal chamber while pulling. Fittings to be specified by vendor. New shipping caps and shipping caps gaskets (plastic and steel). Used shipping caps may be used if in a “like-new” condition. The most recent downhole schematic (including the completion profile); wellbore profile to include pump setting depths (MD & TVD), etc. The most recent ESP run report Any/all well intervention history (inclusive of critical well file information, installation report, etc.) Approved pull procedure detailing throughout the ESP retrieval process

responsibilities

Note: Prior to commencing the pull, the company representative shall review how the protector/seal will be pressure checked in the field. This item cannot be captured after the protector/seal has been disconnected from the motor interface.

11.4. Pulling the ESP 4.1. Critical Pull Observations The following items should be monitored throughout the pulling of the equipment. Wellhead feed condition)

through

mandrel

(mechanical

and

electrical

Monitor cable for mechanical damage Monitor cable for any electrical „blowouts‟ Monitor cable for out-gassing. If this is considered a possibility, the maximum pulling speed should not exceed 6-10 stands per hour. 4

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Confirm number of retrieved cable bands are the same as during the installation Condition of any/all splices in the cable, inclusive of the motor lead extension (MLE) to cable splice. If any splice is suspected of being a problem, the point of the splice should be noted on the pull of the report. If the MLE to cable splice is noted as problematic, the cable shall be cut approximately 2‟-4‟ (~ 1 meter) above, and below, the splice and retrieved for further evaluation. Condition of Pothead Entry Point. NOTE: The pothead should NEVER be disconnected in the field. The MLE should be cut 1-3 feet (~ 0.5-1 meter) above the pothead connection. Discoloration of any pump or motor housing which would evidence extreme temperature. Items noteworthy include: o Blue/black coloring o Paint blistering o Melted lead from the MLE Plugged intake with debris or collapsed intake screen. (Take samples if debris is found) Corrosion of cable and/or equipment Obvious signs of impact to housings or cable Obvious signs that the housings are bent Note and/all electrical arcing damage and exact location. Signs of MLE cutting into housings due to vibration. Condition of cable and protectorlizers (or cable clamps). Any obvious signs of tubing damage (corrosion, holes, collar splits, etc.).

4.2. Disassembly of the ESP at the Well site It is critical that valuable data be captured during the disassembly of the ESP. Customer shall have the right to approve/disapprove the evaluation process of any samples taken during pulling the ESP, inclusive of the evaluation company (laboratory, etc.). 4.2.1 Cable/Feedthroughs/Pigtails Examine the well file prior to pulling the ESP and determine the number of splices (if any) in the ESP cable and the number of bands/cable clamps installed during the installation of the ESP. 5

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 Conduct a megger test through the feedthrough prior to disconnecting from the lower pigtail. Note the readings on the pull report.  Record the serial number of all penetrators and penetrator connectors. Quarantine the penetrators and penetrator connectors for possible further examination.  Examine the feedthrough on the lower side of the tubing hanger. Inspect for any signs of possible mechanical damage.  Examine the lower pigtail to feedthrough connection. Insure the feedthrough and pigtail were properly connected (it will be necessary to refer the appropriate feedthrough manufacturer for the proper make up procedure).  Disconnect the feedthrough from the lower pigtail and conduct a megger test. Note the readings on the pull report. Make note if any fluid is found in the connector when disconnected.  Give particular attention to any unusual signs of tension on the feedthrough and pigtail. Confirm there was some amount of slack left for thermal expansion; note in the pull report.  Closely inspect the splice from the lower pigtail to ESP cable. Examine the splice for signs of excessive heat, mechanical damage, etc.  Inspect the ESP cable for mechanical damage while pulling the ESP.  If the location of the splices are known, or become visible (typically, splice locations are easily identifiable), closely inspect the splice for any signs of damage or potential failure.  Items to note as the ESP is pulled: o Is the cable “out-gassing”? o Loss of bands or cable clamps. o Excessive swelling of the cable. o The condition of the cable armor  Heavily corroded?  Is the armor broken?  Is the armor parted from longitude type stress?  When the cable has been disconnected from the motor, complete a megger test and note results on the pull report. 6

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Electric Submersible Pumps Chapter 10

4.2.2 Check-Valve & Tubing Drain Valve If a check-valve and tubing drain valve were installed; note the distance from the pump to the valves on the pull report. Indicate the type of check & drain valves that were installed. Take digital photographs of the valves, if warranted. Items to evaluate.  Did the tubing pull wet?  Was the check valve plugged or fully operational?  Retrieve any debris samples from the top of the check valve and/or drain valve, if present.  Quarantine the valves for future examination. 4.2.3 Pump(s)/Discharge Head Key items to observe during the disassembly pump(s) (take photographs of any unusual items):

of

the

Debris in the head/intake of the pump? If debris is present – collect samples, place in a plastic bag and label. Debris between pump sections (if more than one pump section was installed). Discoloration of the pump housing(s)? Shaft(s) rotation observations o Check shaft rotation from top end of the top pump before disassembling. o Check shaft rotation of each pump section from the bottom end as each pump section is removed (with pump in a horizontal position). o Check shaft side play (radial stability) at each end of each pump section. o Does the shaft rotate freely? Does the pump or pump trim show demonstrate evidence of corrosion? (Trim is defined as the nuts, bolts washers, etc.). If the equipment was flame spray coated for corrosion protection, is the coating showing signs of degradation or damage from installation/pulling? If the pump(s) were shimmed with loose shims in the couplings (some compression type pumps), place the shims in a plastic bag and label appropriately. DO NOT tamper with 7

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Electric Submersible Pumps Chapter 10

shaft extension report.

screws

or

captive

shims.

Note

on

pull

Was the o‟ring heat set? Insure that the o‟ring remains with the discharge head for future examination. Place new or cleaned shipping caps on the pump(s). Use new o‟rings or gaskets as needed. 4.2.4 Intake/Gas Separator Key items to observe during the disassembly of the intake or gas separator: Check for excessive side play at both ends of the shaft. Is the shaft setting height correct? Did the shaft fall out of the intake? Were the intake ports plugged? If so, take a sample of the debris. Did the intake have a screen? If so, observe the condition of the screen. Was it collapsed? Was debris plugged into the screen? If so, take a sample and place in a plastic bag, identifying appropriately. Was the o‟ring heat set? Insure that the o‟ring remains with the intake/gas separator for future examination. 4.2.5 Protector(s)/Seal(s) It is critical that the shaft seals be checked prior to disassembly of the protector/seal to motor interface. Using the pressure checking equipment as required for the type of equipment being utilized – check to confirm if any pressure is contained between the protector (seal)/motor interface point. Pressure checking equipment consists of the proper tool to connect to a drain/fill location at or near the head of the motor/seal interface. The check shall be read on a pressure gauge (0-50 psi). If a seal is found to be leaking, capture the leak with a photograph. Capture fluid samples while disassembling the protector/seal from the motor. Observe for well fluid contamination and note on the pull report. Captured well fluid samples shall be returned to the vendor‟s service center for further examination during the equipment teardown. When disconnected from the intake, observe if there is any material in the head of the protector/seal. 8

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Check the shaft for radial stability. Note: Drain all labyrinth chambers prior to laying down the seal/protector. Consult with the manufacturer‟s field service technician. Place new or cleaned steel shipping caps on the protector/seal and place in a shipping box or on a proper supporting surface on a trailer. 4.2.6 Motor(s) Key items to observe during the disassembly motor(s) (take photographs of any unusual items):

of

the

NOTE: Do NOT disconnect the pothead from the motor. If at all possible, cut the MLE at least 3 feet (~1 meter) above the pothead or above the upper most thrust bearing in the protector/seal. This will allow examination of the cable condition where it passes by the thrust bearing in the protector/seal. Discoloration of the motor housing(s)? Electrical readings of the motor. Attempt to “smell” the motor oil and note if the oil has a “burnt” smell. Capture fluid samples from the motor head & base as well as any connection points (if tandem motors). Observe for well fluid contamination and note on the pull report. Captured well fluid samples shall be returned to the vendor‟s service center for further examination during the equipment teardown. If tandem motors; observe the connection point between the motors. Make note of any unusual events such as bent connection points, cracked insulators, etc. If a sensor/gauge to the connection mechanical damage. of the motor. The still connected.

was installed, give particular attention and observe for any signs of leaks or DO NOT disconnect the gauge from the base motor should be returned with the gauge

Observe rotation of the shafts and make note on the pull report how the shaft turns. Place new, or cleaned, shipping caps on the motor(s) (only steel shipping-caps to be used on motors; plastic shipping9

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caps are not acceptable). Place the motor in a shipping box or on a proper supporting surface on a trailer. 4.2.7. Downhole Monitoring Devices (Sensors) DO NOT disconnect the gauge from the motor if at all possible. If the gauge must be disconnected at the well site, proceed with the following steps. Key items to observe during the disassembly of the gauge from the motor (take photographs of any unusual items): Note any impact loading on the bottom of the gauge. Observe motor.

the

connection

point

when

disassembled

from

the

Observe for well fluid contamination. Place new or cleaned shipping caps on the device. Use new gaskets or o‟rings as needed.

5.0 Dismantle, Inspection & Failure Analysis (DIFA) 5.1. Preparation The dismantling of the ESP shall be conducted in a controlled environment where extensive observations can be completed. It may not be necessary to dismantle all pieces of the ESP. Each component shall be evaluated for bench testing prior to commencing the dismantling of the respective component. Customer shall determine if a component shall, or shall not, be dismantled based upon test data and data supplied by the manufacturer. Customer shall have the right to approve/disapprove the evaluation process of any samples, inclusive of the evaluation company (laboratory, etc.). Prior to commencing dismantle operations, identification cards shall be prepared. These cards shall contain the following information for each component and should be visible in any photographs taken of the component: Well Identification Component Identification Serial Number Date of dismantle In addition to the standard tooling to disassemble the ESP, the following tools/items shall be available: Original sizing data (hard copy to be present at dismantle if available) Pull & Run Report. 10

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Field service operation.

reports

(if

any)

during

the

period

of

Operational data captured immediately upon failure of the ESP (inclusive of all relevant well file information) Any/all samples taken during the pull of the ESP Magnifying glass with high intensity lamp. Calipers to measure bearings/bushings/pump stages, etc. Long jaw calipers Shore “A” hardness tester Drop gauge Hole Mics Metal ruler and tape measure Magnet Multiple flashlights with high intensity beams 12 each, 1 pint, plastic sample bottles. 24 each, 1 quart, plastic bags (zip-lock type). 36 each 3” x 6” cards (blue or white preferred) to be used as identification markers in photographs. Permanent markers. Dry air source or nitrogen (avoid using compressed air that is not properly dried). Round plastic containers for storing items such as shaft seals, etc. Digital Camera.

5.2 Cable In many cases, the cable is examined and tested separately from the ESP equipment dismantle. Customer shall reserve the right to witness any testing and repair that may be done to the cable.

5.3 Pump(s) The following provides the minimum requirements for dismantling the pump section(s) of an ESP. Required reference documents, or information from vendor:  Stage compression details  All major wear surfaces dimensions and tolerances as follows: 11

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Balance Ring

Vane

Ring Groove

Mixed flow impeller 12

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Electric Submersible Pumps Chapter 10

Radial flow impeller 

Skirt



Bore



Hubs



Sleeves



Bushings Shaft settings Pump Test Report (new)

Prior to disassembling the pump section, the shaft shall be checked for rotation. If the shaft rotates, customer shall determine if the pump shall be placed on a pump test bench and tested prior to dismantle. If possible, flush the pump prior to testing and collect any samples that may be flushed from the pump. Also, prior to disassembly, ask that a new pump stage be provided for comparison purposes. The new stage will allow a visual comparison in key areas of the pump stage. Pump Dismantle Verify the pump serial number on the nameplate. Inspect the condition of the pump housing o Check for scale buildup, collect samples if present. o Inspect the housing for corrosion and/or holes in the housing. If holes are present, note the location relative to the bottom end of the pump. o Check for mechanical damage cable, scratching and bends).

(dents,

vibration

from

the

o Visually inspect the housing for straightness (flop test). o If the pump(s) have a flame spray corrosion coating, visually inspect the coating and note any areas where the coating is not intact.

13

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o Check for any signs of heat that would result from spinning diffusers. Shaft Settings & Inspection o Check the shaft for ease of rotation (typical nomenclature is: free, rough, hard or stuck). o Confirm the shaft is rotating at the opposite end of the pump. o Take the appropriate head and base measurement for the shaft settings. Compare these to the manufacturer‟s factory settings. o Push the shaft to the down position and take measurements; repeat in the up position. This will determine the shaft’s axial movement. Compare to the manufacturer‟s factory settings. o If applicable attach a dial indicator on the inside of the shaft spline, or on a coupling, to measure run-out when the shaft is rotated. Repeat this procedure on either-end of the pump. Compare to the manufacturer‟s factory settings. Head & Base Inspection o Remove the head and inspect the bushing for wear, plugging, corrosion, erosion. Inspect the condition of the threads on the head. o If the pump has a threaded bearing support, measure the distance from the end of the housing to the top of the bearing support to determine the gap between the head and support. o Inspect the bearing support for attention to corrosion and erosion.

wear

with

particular

o If it is a compression type pump remove the compression per the manufacturer‟s instructions. Thereafter, remove the base and complete a similar inspection as was conducted on the pump head. o Pull/push the impeller and diffuser stack from the housing. Note: insure that the snap rings and 2-piece rings are in place (consult with the manufacturer for each pump‟s specific design). o Note on the dismantle report if the impeller and diffuser stack are difficult to pull from the housing.

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O-rings o Check all o-rings for damage such as extrusion, feathering, explosive decompression, compression set, etc. Observe for any signs of leak past the o-ring. o Give particular attention to any o-rings on the OD of the diffuser. Observe the o-ring for swelling and hardness (due to heat, etc). Impeller & Diffuser, Bearing Sections Inspection o Wipe off the OD of the diffuser stack and number the stages from bottom (stage #1) to top (stage #X). o Remove the stages and shaft from the housing. Slide all stages off the shaft with sleeves and spacers. o Note any diffusers that show signs of spinning on the exterior. o Inspect the o-rings that are in the pump stages (diffuser OD). o Inspect all impellers for any signs of thrust, abrasive wear and/or radial wear. Give particular attention to the pads, bores and hubs. Check for one-sided wear. o Observe all components for discoloration that would indicate wellbore fluid damage or possible heat damage. o Randomly remove some of the thrust washers and check for thickness and brittleness. Note the type of thrust washers and compare with a new thrust washer. Confirm the same type of thrust washers were used throughout the pump. o If any foreign material is found in the pump, collect a sample for further analysis and testing. Label on the collection bag the location of the material. o With the pump components laid out from base to head, take key measurements in the top five stages, middle five stages and bottom five stages. All wear surfaces should be measured (e.g. skirts, bores, hubs, sleeves, bushings etc.). This information will be used later to plot a trend analysis. Note, the manufacturer‟s dimensions and tolerances of all components will be required. The manufacturer should supply this information in advance or at the time of the dismantle. o Inspect the bushings and sleeves between the stages for wear, cracks or abrasive indications. Note the material type of the bushings and sleeves and the spacing of any abrasion resistant (AR) bearings. 15

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o Note and record the spacing of any/all stage bearings. Shaft Inspection o Visually inspect the shaft spline on both ends. Observe the splines for straightness and coupling engagement. If a coupling is only partially engaged damage may be noted at the upper end of the spline. Refer to the manufacturer‟s guidelines for checking shaft straightness. o Place the shaft on a bench with the keyway facing up. Observe the shaft for straightness or twisting. o If the shaft utilizes shim nuts – remove and measure with a caliper. o Inspect

the shaft surface of any obvious issues such as pitting, galling, erosion beneath the shaft sleeves, onesided wear, etc.

5.4 Intakes/Gas Separators The intake/gas separator and discharge dismantled in conjunction with the pump.

head

should

be

Required reference documents, or information from vendor: Head/base bushing dimensions & tolerances Visual Inspection o Inspect the O.D. of the housing for corrosion, pitting, burns, mechanical damage, scale, holes, etc. o A note should be made if the O.D. has a corrosion resistant coating, and whether or not the gas separator has shipping caps. o After the respective internal parts are removed, the condition of the I.D. as well as internal parts should be examined noting any erosion, corrosion, or other abnormalities. Bearings and Bushings o Inspect all bearings, bushings and sleeves noting wear (one-sided or concentric), presence of foreign materials and general condition. Collect samples of any foreign materials. Shaft o Turn the shaft and note whether it turns free, hard, rough or stuck. Note condition of shaft and splines, including wear or twisting, corrosion or other mechanical damage.

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Intake Screen o Observe condition of intake screen, noting presence of foreign materials or screen collapse. Note if an intake screen was not present. If the intake screen is not present – was it noted on the installation report?

5.5. Protector(s)/Seal(s) The following provides the minimum requirements for dismantling the protector/seal section(s) of an ESP. Required reference documents, or information from vendor: Manufacturer‟s specific dismantle procedure appropriate protector/seal to be dismantled.

for

the

Shaft settings & dimensions, tolerances Head & base bushing dimensions and tolerances Specification for bag material hardness (Shore “A”) Seal Test Report (new) Reference vendor documents for testing bag type and labyrinth protectors/seals. Standard for testing dielectric breakdown of insulating liquids. (Reference ASTM D-877-Standard Test Methods for Dielectric Breakdown Voltage for Insulation Liquids using disk electrodes). Protector/Seal Dismantle (while is it necessary to follow the dismantle guidelines of the specific manufacturer, it is imperative that the following items be inspected, at a minimum. Compare the two documents to insure that all of the following steps are met.) Verify the protector/seal serial number on the nameplate. Inspect the condition of the protector/seal housing o Check for scale buildup, collect samples if present. o Inspect the housing.

housing

for

corrosion

o Check for mechanical damage cable, scratching and bends).

and/or

(dents,

holes

vibration

in

the

from

the

o Visually inspect the housing for straightness. o If the protector/seal has a flame spray corrosion coating, visually inspect the coating and note any areas where the coating is not intact. o Inspect the vent holes for plugging or debris. 17

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o Visually inspect the drain and fill valve locations for any extruded lead gaskets. Coupling(s) o Inspect the coupling closely with a flashlight. o Look for any stress damage in the splines. o If debris is found, collect a sample. Perform a housing leak test at the various vent ports (this will be manufacturer specific; refer to the appropriate manufacturer for the exact locations and pressure sequence). The goal of this step is to test each housing connection point to verify integrity. Use soapy water to inspect for leaks. Give particular attention to lock plates and/or joint welds (if utilized). Cut lock plates/joint welds if required. Disassembly of the protector/seal (Note: it is imperative to refer to the specific manufacturer guidelines for protector/seal disassembly. Each protector/seal type will vary depending on the manufacturer and type of protector/seal utilized.) o Check the shaft for ease of rotation (typical nomenclature is: free, rough, hard or stuck). o Confirm the shaft is rotating at the opposite end of the protector/seal. o Push the shaft to the down position and take measurements; repeat in the up position. This will determine the shaft‟s axial movement. Compare to the manufacturer‟s factory settings. o Attach a dial indicator on the inside of the shaft spline, or on a coupling, to measure run-out when the shaft is rotated. Repeat this procedure on either-end of the unit. Compare to the manufacturer‟s factory settings. o The protector/seal is to be positioned at a minimum 45 degree angle to insure the mechanical seal is covered with oil.

o Starting air the the for

at the head of the protector/seal, apply 5 psi of pressure through the appropriate vent hole and rotate shaft in both directions. If no bubbles are observed, mechanical seal is good. Air pressure is to be applied minimum of (2) minutes

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o Before checking. If the mechanical seal leaks, replace the shipping cap and repeat the test, soaping the joints to observe for leaks. o Continue disassembling the protector/seal from the head down. Repeat the process of checking each mechanical seal as it is reached. Each time, insure the protector/seal is at, or near, a 45 degree angle prior to checking the mechanical seal. o As valves are removed from the protector/seal, inspect the integrity of the lead gaskets. Give attention to any areas where the lead gasket was not properly deformed (compressed) for a possible leak path or where the lead gasket may have been fully extruded due to being overtightened. Note findings on the report. o Check all o-rings for damage such as extrusion, feathering, explosive decompression, compression set, etc. Observe for any signs of leak past the o-ring. Inspection of Mechanical (Shaft) Seals o Remove the snap ring that holds the mechanical seal and slide the mechanical seal from the shaft. o Remove and inspect the runner surface. o Inspect the mechanical seal bellows, spring, runner and seat for wear, scoring, chipping or broken face. Check the elastomer for pliability ‫مرونة‬, stiffness, hardness. Parts should be labeled and sealed for further inspection at a later date, if required. Inspection of Chambers & Bags o Inspect each chamber for corrosion, condition of threads contamination, etc. Fluid samples shall be taken from each chamber and identified appropriately for future examination if appropriate. o Inspect each bag, bag clamps and general condition. Note the amount and type of fluid in the bag and on the outside of the bag. Obtain samples in all sections. Insure samples are labeled as collected from the different chambers, inside the bags, etc. o Inspect the external condition of any/all bags. Give particular attention to the area of the bag clamps and along the seam of the bag. o Where applicable, remove the bag frame assembly (once again, refer to the specific manufacturer guidelines and procedures). After sealing the bag frame, inflate with air 19

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and submerse the bag frame into water and look for air bubbles. o Locate the markings on the bag and identify the material (the manufacturer may utilize a specific code). Check the bag for splits, bubbles, evidence of decompression, etc. o Where applicable, remove the bag from the guide/frame and inspect for well fluid or other foreign material. If any foreign material is found, collect a sample for further evaluation. Once again, collect fluid samples from inside the bag and identify appropriately. Additionally, collect a sample of the bag material and place in a plastic bag for possible future laboratory examination. Thrust Bearing Inspection o Remove the thrust bearing from the thrust chamber per the manufacturer‟s recommended procedure. o Inspect the base bushing for any wear such as scoring, oneside wear or galling. o Inspect the thrust bearings and both sides of the runner for any signs of operating in water, up thrust, down thrust, uneven wear, deflected thrust runner, scoring, excessive heat, fretting, etc. o Fretting (or fretting corrosion) - The ASM Handbook on Fatigue and Fracture defines fretting as: "A special wear process that occurs at the contact area between two materials under load and subject to minute relative motion by vibration or some other force." Head & Base Bushing & Shaft Inspection o For the head and base locations, examine for bushing wear, scoring, leak tracks, o‟ring groove condition and internal/external corrosion. o Examine the shaft at the bushing and seal surfaces and note any unusual wear (e.g. one-sided), scoring, etc. o Visually inspect the shaft splines for straightness coupling is only partially damage at the upper end of

spline on both ends. Observe the and coupling engagement. If a engaged damage may be noted with the spline.

o Observe the shaft for any “frosting” that may occur. “Frosting” is defined as the transfer of base bushing material on to the motor shaft. o Place the shaft on a bench straightness or twisting. 20

and

observe

the

shaft

for

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o If the shaft utilizes shim nuts – remove and measure with a caliper. o Inspect the shaft surface of any obvious issues such as pitting, galling, one-sided wear, etc.

5.6. Motor(s) (Includes the MLE & Pothead) The following provides the minimum dismantling the motor(s) section of an ESP.

requirements

for

Required reference documents, or information from vendor: Shaft settings Shaft settings & dimensions, tolerances Head & base bushing dimensions and tolerances Rotor, rotor bearing dimensions, tolerances Any other relevant dimensions as required by the specific manufacturer Motor Test available)

Report

(new)

(include

the

vibration

data

if

Motor pit test (if applicable). Motor Winding Information (to include details magnet wire splicing during original manufacture).

regarding

Standard for testing dielectric breakdown of insulating liquids. (Reference ASTM D-877-Standard Test Methods for Dielectric Breakdown Voltage for Insulation Liquids using disk electrodes). Review the electrical readings from the pull report and reconfirm. Complete an electrical check on the motor prior to removing the MLE connection at the pothead if possible. At a minimum, the motor should be: ► Megger test ► Resistance readings taken ► KV (dielectric) test on an oil sample taken from the base of the motor Refer the specific manufacturer for minimum readings. Prior to removing the MLE/Pothead or gauge (if attached)

acceptable removing a

► Perform a pressure test on the motor housing. Connect an air hose (be sure to use either a dry air source or nitrogen) to the drain/fill valve and apply 10 psi. Hold for a minimum of 1 minute, monitoring to confirm the motor holds pressure. If the pressure drops below 10 psi, spray soapy water at the 21

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pothead, head/base joints to ascertain the location of the leak. If the motor passes the initial electrical inspection, the motor should be tested per the manufacturer‟s recommended guidelines. If a recommended guideline does not exist, the motor can be raised to a vertical position and flushed with appropriate new motor oil. Use a new piece of filter paper to drain the oil from the motor to collect any solids that may be present. Refill the motor with new motor oil and repeat the process, using a second piece of filter paper. After the second refill, place the motor on the motor test bench and complete a full slant idle motor test. The motor vibration should be recorded during the slant idle test. Compare the vibration data to the original motor test data. Any solids removed from the motor should be evaluated as to their origin (i.e. brass shavings, sludge, etc.). If the motor passes the slant idle motor test, prepare to hi-pot the motor. If the motor fails the slant idle motor test, proceed to dismantle. Complete a final KV (dielectric) test on an oil sample taken from the base of the motor. Motor Dismantle Verify the motor(s) serial number on the nameplate. Inspect the condition of the motor(s) housing o Check for scale buildup, collect samples if present. o Inspect the housing.

housing

for

corrosion

and/or

holes

in

the

o Check for mechanical and electrical damage. o Visually inspect the housing for straightness. o If the motor has a flame spray corrosion coating, visually inspect the coating and note any areas where the coating is not intact. Remove Shipping Caps o Inspect the shipping caps for any signs of debris, solids or water since being pulled from the well. Remove the remaining MLE & Pothead o Inspect and test the pothead for any signs of possible damage such as: ► Look for signs of heat ► Confirm the age of the MLE/Pothead – was it reused? ► O‟ring damage 22

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► Surface damage to the sealing areas ► Elastomer integrity ► Check the pothole for evidence of fluid tracking. o If a sample was collected and tested during the slant idle test, the following “3” steps are not required. ► Drain the motor oil from the motor; collect a sample for dielectric testing. This sample should be compared to the sample collected when pulling the equipment from the well. ► Check the condition of the motor oil and note on the report (standard nomenclature is: clear, dark, emulsified, metal/brass shavings). ► After completing the dielectric test on the motor oil, observe the motor oil for well fluid by letting it set for a period of time to ascertain if anything settles out on bottom, or top, of the motor oil. o Complete an electrical pothead connected.

check

of

the

motor

without

the

o If tandem motors, complete individual electrical tests of each motor. Shaft Settings & Inspection o Check the shaft for ease of rotation (typical nomenclature is: free, rough, hard or stuck). Rotate the shaft by using a motor coupling and an insert tool to turn the shaft. o Confirm the shaft is rotating at the opposite end of the motor. o Measure the shaft axial/lateral movement. Compare to the manufacturer‟s factory settings. o Use a dial indicator to check run-out at the head and base of the shaft. Compare to the manufacturer‟s factory settings. Thrust Bearing & Runner o Remove the thrust bearing and runner, inspect same. o Check the condition of the runner face and surface. o Check the galling.

thrust

bearing

for

scoring,

smearing,‫ملوث‬

Remove the Motor Head & Rotor String o After removing the motor head, inspect the head bushing for any abnormal wear. Check the o‟ring sealing area for any 23

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signs of damage and a resulting leak path. Typically, leak paths will have be manifested in a discolored area. o Check the galling.

threads

on

the

motor

head

for

any

signs

of

o Check the lead cables for physical or electrical damage. o Check the condition of visible signs of a burn.

the

end

coils

for

obvious

and

o If the stator is grounded, look for carbon trails, copper balls to lead to the location of a burn. o If necessary, insert a scope into the stator and inspect. o Check all o‟rings for damage such as extrusion, feathering, explosive decompression, compression set, etc. Observe for any signs of leaks past the o-ring. o If the rotor string was difficult to remove, check for any areas where heat may have affected the string resulting in warping. Check for straightness. o Inspect each rotor for discoloration and rotor strike. Typically, the rotors will be gray in color with copper colored end rings. o Note any discoloration of the copper. attention if the copper appears black indication of H2S.

Give particular as this is an

o Inspect the rotor bearings for spinning (if non-locking type rotor bearings). If the manufacturer used a locking rotor bearing – inspect/confirm the rotor bearing locked correctly. This may vary from manufacturer to manufacturer. o After removal of the rotor string, inspect the slot liner to determine if it is in its proper position. Determine if it has “shrunk” into the slots. Perform Electrical Check on the Stator o Check the stator for phase to phase balance. If the motor section is an upper tandem or center tandem motor, it will be necessary to connect the phases together at the base of the motor. The sequence for checking the stator should be: A-B; B-C, C-A. Under normal conditions, the stator should be balanced phase to phase within 5%. Refer to the appropriate manufacturer‟s guidelines. Compare the readings to the original readings taken at time of manufacture or the most recent available readings (e.g. readings taken prior to installation). 24

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o After checking the stator phase to phase, remove the jumper at the base of the motor and check for resistance to ground. Use a minimum of a 1000 VDC megger (a 5000 VDC megger is preferred if available). Typically, the reading on each phase should read 2000+ meg ohms. Be sure to discharge the phase after testing to ground. o Note: if the stator tests grounded and the burn is not easily visible, destructive testing may be required. Destructive testing requires the stator to be cut in sections to expose suspected areas of a possible failure. Rotor, Thrust Washer, Rotor Bearing & Sleeve Removal o Check the condition of the thrust washers. If the thrust washers have been exposed to excessive heat they will be brittle. Also inspect the thrust washers for abnormal wear. o Inspect the rotors for wear, any signs of possible rotor strike against the stator and any residue buildup on the OD/ID of the surfaces. o Dimensionally check the rotors and rotor bearings. o Inspect the rotor bearings for any (assumes a non-locking rotor bearing).

signs

of

spinning

o Inspect locking rotor bearings for engagement. o Inspect all components for discoloration due to heat or exposure to well fluid. Base Inspection o Check all o-rings for damage such as extrusion, feathering, explosive decompression, compression set, etc. Observe for any signs of leaks past the o-ring. o Check the base bushing for abnormal wear, grooving or one sided wear. o Check all connection points for arcing or burns. o Check the end coils for burns. Final Shaft Inspection (after removal of rotors) o Inspect the shaft for signs of heat or any abnormal wear. o Check the head and base scoring or excessive wear. o Check the scoring.

sleeve

surfaces

bushing for

for

discoloration,

o Inspect the oil holes for plugging. 25

areas

polishing, wear

and

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5.7 Downhole Monitoring Devices (Sensors) If a downhole monitoring (i.e. sensor, gauge, etc.) is installed conduct an evaluation of the component. o Complete an inspection of the erosion and mechanical damage.

housing

o Follow the manufacturer‟s guidelines electrical/electronic integrity test.

for

and

corrosion,

complete

an

o Inspect the connection point between the motor and the monitoring device. Note any unusual damage. o For a motor oil sensor, document the length of the lead to the thermocouple.

6.0 Root Cause Analysis (RCA) & “The Why Analysis” The purpose of Root Cause Analysis (RCA) is to enable an investigation (in this case – failure analysis) to produce sufficient learning to prevent recurrence, or to have an excellent chance of preventing recurrence, of whatever undesired event or issue is being investigated. In order to have sufficient learning, a Root Cause Analysis shall identify the physical, human and latent cause(s), of the undesired event or issue. If we do not identify and correct the physical, human and latent cause(s), the undesired event or issue may repeat if the same cause triggers similar undesired events or issues in the same or other equipment, systems, processes, etc. There are generally two types of application of root cause analysis: a) significant sporadic events, or b) significant chronic issues. Sporadic:‫ متقطع‬Significant sporadic events are low-frequency, high impact events that are typically very visible and severe. Chronic:‫ مزمن‬Chronic issues are typically high-frequency, low impact (per occurrence) issues that may not be very visible, but over time, usually exceed the cost of sporadic events when the multiple impacts are accumulated. A focus on chronic issues will typically have the most impact. o What is deemed to be “chronic” can be relative. For example, suppose an offshore platform shuts in twice within a six-month period of time for the same reason, resulting each time in a significant loss of production. That could be considered chronic even though it is neither “high frequency” nor “low impact” per occurrence. 26

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Evidence Gathering o While this recommended practice is concerned primarily with analysis of evidence, it should be understood that evidence gathering itself, is an essential part of a quality investigation. The people who gather evidence must understand what evidence should be gathered and how to gather that evidence. They must be able to interpret the information, and they must have the ability to accurately convey that information. Anyone designated to gather evidence should have received proper training or be under the direct supervision of someone who has been so trained. Root Cause Analysis Determination o As stated earlier in this section, a Root Cause Analysis shall identify the physical, human and latent cause(s), of the undesired event or issue. If the physical, human and latent cause(s) are not identified and corrected, then the undesired event or issue may repeat if the same cause triggers similar undesired events or issues in the same or other equipment, systems, processes, etc. o Undesired events begin with a physical cause. For example, the shaft broke (undesired event) because it failed in fatigue as a result of rotating bending stresses (physical cause). This is where many investigations stop. The root cause analysis shall not stop at this point. Identification of the true physical cause is not a mere formality - it is critical that the physical cause is accurately determined. Going further to identify human and latent causes for an incorrectly identified physical cause will not necessarily prevent recurrence. o People do things, or don‟t do things, that enable or trigger physical causes, and these are the human causes; for example, the mechanic misaligned the motor and the pump. In the case of human error, there are only two categories: 1) knew, but didn‟t do, or 2) didn‟t know, and therefore couldn‟t do. The Why Analysis o The “Why Analysis” is conducted by repeatedly asking the question "Why". Using this technique you can peel away the layers of symptoms which can lead to the root cause of a problem. Very often the apparent reason for a problem will lead you to another question. To complete the why analysis ask “Why?” the immediate cause occurred and write that answer down. If the answer doesn't identify the root cause of the problem, ask “Why?” again and write that answer 27

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down. Continue this process until a root cause is identified. Writing the answers to the why question allows you to start documenting the sequence of events that lead up to the incident. Use the criteria below to identify when a root cause is found. Benefits of using the Why Analysis o A very simple tool to use o Helps to identify the real root cause(s) of the incident o Determines the relationship between different root causes of a problem by establishing the sequence of events o Allows creation of solutions that remove the underlying root causes o Not only identifies causes and solutions to eliminate the reoccurrence of the immediate event, but eliminates the occurrence of similar events that could occur if the root cause(s) are not removed.

7.0 DIFA Report Format The format shall be consistent for all reports. The reports shall have a designated numbering format, preferably sequentially numbered. The report shall contain a header and footer that contain consistent information throughout the report. The header shall contain: o Company Name o Title o Reference Report number o Well Name The footer shall contain: o Issue/revision number o Page “x of y” numbering format. The completed DIFA Report shall be submitted to the local customer Engineering Manager/Supervisor/Engineer, as designated by the local business unit. The local business unit shall submit a report to the Artificial Lift team leader. Electronic copies are acceptable.

7.1 Cover The cover shall reference a specific DIFA report number; identify the appropriate business unit and well name/number.

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7.2 Table of Contents The table of contents shall detail each major area in the report and an associated page number.

7.3 Distribution List The distribution list page shall identify all parties that the report is distributed to (inclusive of Customer personnel as well vendor personnel). This page shall also identify the person that conducted the dismantle inspection as well as the person(s) which wrote the report.

7.4 Well Information This page shall be considered the executive summary. This section shall contain the following information: o Business Unit Identification o Well Identification o Run Date o Failure Date o Pull Date o Run Life (in days) o Reason for Pull o Dismantle Date o Report Date The written portion of this page shall state the following, under individual headings: o Objective – a short description of the objective of the DIFA. o Well History – a brief overview of major incidents in the life of the well from the run date to pull date. All unusual events should be highlighted in this paragraph. o Pull Report – a brief description of observations during the pulling of the unit. o Summary – a short paragraph evaluated cause of failure.

detailing

the

failure

and

7.5 Trend Analysis This section should contain graphs/charts from available well monitoring packages such as LOWIS, SCADA or Well view. Customer shall make this information available to the vendor‟s application engineer. 29

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7.6 Electric Submersible Pump Identification Information This section shall give complete descriptions of the failed ESP in a table format. The table shall consist of Equipment Description, Serial Number and Part Number.

7.7 Dismantle Inspection Findings This section consists of multiple pages. The order of this section shall be from top to bottom on the ESP (i.e. pump, intake, seal/equalizer/protector, and motor). Each component section shall contain the following: o Header section identifying the component and it‟s proper description; serial number; part number o Exterior Inspection o Head/Base Condition o Shaft Condition o Component(s) Condition with extensive descriptions o Summary of finding for the specific component

7.8 Summary of Results & Statement of Root Cause This section shall contain 3-6 paragraphs summarizing the findings of the DIFA. The statement of the root cause of failure shall be made in this section.

7.9 Recommendations This section shall contain 1-4 paragraphs recommending future changes or highlighting key areas to monitor.

7.10 Photograph Gallery This section shall consist of multiple pages of important photographs that contribute to the issues discovered in the DIFA. The page shall have 2 photographs per page, maximum. The photographs shall be of consistent size and shall have sufficient quality to identify the item being described. A detailed description of the photograph shall be at the bottom of each photograph or at the bottom of the page if a single description is sufficient for both photographs. Where applicable, the photograph shall utilize embedded arrows and descriptions. Finally, as appropriate, a rectangular description card should be included in the photograph that identifies the well, item and serial number

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Pump Photographs

Coating flaking

Pump Housing Coating Flake (flame spray type coating)

Drag Marks

Drag Marks on Pump Housing

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Cut o’ring & brittle

Cut O‟ring on Pump Head (Note: the o‟ring appears to be brittle as well)

Scoring

Scored Bushing in Pump Base

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Severe Bushing Wear

Tubing fallback deposits

Pump Head – likely deposits from tubing “trash”

33

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Spinning Diffusers; note marks on diffuser OD

Spinning Diffuses

Typical One-Sided Pump Shaft Wear

34

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Twisted Pump Shaft at Spline

Twisted Shaft Along Keyway 35

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Scale in Pump Stage

Cracked Impeller Hub – Crack Along Keyway 36

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Eccentric destroy Impeller hub

Impeller hub completely destroyed 37

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Destroy in diffuser hub

Severe Downthrust Wear versus New Impeller 38

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Impeller with Whipping

Upthrust on Impeller

Light Upthrust Wear on Impeller 39

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Heavy Upthrust Wear on Impeller

Broken Hub

Heavy Upthrust Wear with Broken Hub

40

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Medium Wear Area

Diffuser Bore with Medium Wear

Medium Wear Area

One Sided Radial Wear

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Severe downthrust

Severe upthrust

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Plugging with scale

BOI & GS Photographs

Collapsed Intake Screen

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Severe Erosion

Severe Intake Erosion

Plugged Gas Separator from Asphaltines

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Broken Inducer

Damaged Gas Separator Inducer

Erosion in BOI exit ports

45

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Erosion in GS against axial impeller

Severe erosion in GS against axial impeller

46

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Erosion in BOI inlet ports

Hole in GS (Corrosion)

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Scoring in zirconium bearing Protector/Seal Photographs

Corrosion in the Lockplate Area

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MLE vibration marks on the seal/protector housing

Water in a Seal/Protector

Water in the Chamber of a Seal/Protector 49

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Scale Deposits on Mechanical Seal

Damage to elastomer of seal due to heat

Damage to Seal Bellows Due to Heat 50

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Severe Corrosion on the Seal/Protector Tube

Severe Deposits on the Exterior of the Seal/Protector Bag (All Deposits Should be Collected and Examined by a Laboratory) 51

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Bubbles in the bag can be caused be defects, chemicals, heat, etc.

Bubbles in the Seal/Protector Bag

Damage to a Seal/Protector Bag

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Damage to a bag from the application of a clamp

Damage to a Seal/Protector Bag at the Clamp Area

New thrust bearing (Solid shoe) 53

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New Thrust runner

New thrust bearing (high load 9 pads)

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New Thrust runner (High Load)

Sever thrust load

55

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Heavy Smearing of Standard Thrust Bearing

Heavy down thrust damage – note the pad stuck to the runner

Severe Damage to Thrust Bearing due to Down Thrust

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Note the damage on the shaft where the bushing is located

Damage to Seal/Protector Shaft at the Bushing Surface

Broken Seal/Protector Shaft (Note: never try to put the ends of the shaft back together. The ends should be examined under a microscope.) 57

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Frontal View of Broken Shaft

Shaft Break – often a shaft break will occur at, or near, the spline area of the shaft as this is the weakest area. 58

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Motor Photographs

Inspect o’ring area for damage

Motor Pothead Hole

Burn on motor head

Motor Head Burn (Flat Cable Area)

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Failed Pothead at MLE/Pothead Interface

Blowout of Pothead

Massive Pothead Burn

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Rotor subjected to light heating effect

Rotor subjected to medium to high heating effect

Rotor subjected to high heating effect

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Dielectric oil contaminated with well fluid

Failure in protector(s)/seal(s)

Rotor Strike

Rotor Strike

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Rotor Strike Area of “Sectioned” Motor

Rotor Strike on Motor Laminations

Lead burn (from endturn on motor)

Burn on Lead from End-Turn

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Burn between endcoils – classified as a “coil-to-coil” burn

Coil to Coil Burn

64