Bond Log Quick Reference Handout[1]

Cement Bond Log Quick Reference Good Bond To Pipe & Formation

Example Bond Tool

Good Bond To Pipe Low 3’ amplitude Late, inconsistent 3’ travel time

Bow Spring Centralizer

No pipe arrival in the VDL

Collar Locator

Low radial amplitudes Gamma Ray & Telemetry

CBL RBL 7

8

1

6

5

4

2 3

Good Bond To Formation

Transmitter

Good Formation arrival in VDL

2’ Radial Receiver Array

Travel time tracks changes in lithology

3’ Receiver 5’ Receiver

Bow Spring Centralizer

CBL - Cement Bond Log (GR-CCL, 3’ & 5’ receivers) RBL - Radial Bond Log (CBL + Array of 8 Radials)

Free Pipe No Bond To Pipe

Good Bond To Pipe & Formation - Good bond to pipe is characterized by a low 3’ amplitude, transit times of something other than pipe arrivals (which are consistent), lack of pipe arrival in the VDL and low 2’ radial amplitudes (if RBL). Good bond to formation can be assumed if the VDL exhibits strong formation arrival suggesting good acoustic coupling between cement and the surrounding formation. Travel time will also track lithology.

Good Bond to Pipe & Poor Bond to Formation Good Bond To Pipe

High, consistent 3’ amplitude

Low 3’ amplitude

Consistent 3’ travel time

Late, inconsistent 3’ travel time

Straight collar effect surrounded by chevron pattern

No pipe arrival in the VDL

Pipe arrivals in VDL - “train tracks” High radial amplitudes

Low radial amplitudes Poor Bond To Formation

Formation Bond? No formation arrivals in VDL

Free Pipe - No bond to pipe (free pipe) is characterized by a high, consistent 3’ amplitude, consistent 3’ travel time, high radial amplitudes, strong pipe arrivals (train tracks) and chevron patterns in VDL. No formation arrivals are present in the VDL as no cement is present to carry acoustic signal to formation and back to the receivers. Cased Hole Logging TCP and Conventional Perforating Swabbing Specialty Services

Little to no Formation arrival in VDL Travel time arrives late (in this case off scale) suggesting something other than pipe or formation. Good Bond To Pipe & Poor Bond to Formation - Good bond to pipe is characterized by a low 3’ amplitude, transit times of something other than pipe arrivals (which are consistent), lack of pipe arrival in the VDL and low 2’ radial amplitudes (if RBL). Poor bond to formation may be assumed if the VDL does not exhibit strong formation arrivals (may not be present at all). Must be aware if VDL is from 3’ or 5’ as mud may be confutes with formation. Brooks - 403.501.8474 Red Deer - 888.309.3055 Whitecourt - 780.778.4505 Grande Prairie - 780.538.1108

Cement Bond Log Quick Reference Fast Formation

Channel Fast Formation

Channel Channel may not be identified on 3’ amplitude (average of 3’ section).

Earlier-than-pipe arrival time Earlier arrival time on the VDL Wavy VDL.

Mapping of 2’ radials identify channel.

No chevrons in VDL Low radial amplitudes

Channel may appear as a spiral due to the tool spinning out of the hole.

Channel - a channel is a potential conduit for formation fluids from one zone to communicate with another, contaminate groundwater or allow for fluid/gas communication to surface in the form of surface casing vent flow or gas migration. Radial bond logging allows for the identification of channels not readily identified on basic cement bond logs.

Light Weight Cement

Light Weights Amplitude may not reach 0 mV but will “flat-line” at a new 100% bond up to +/- 10 mV. First arrival in VDL and travel time will be pipe as signal not fully attenuated.

Fast Formation - to get formation arrivals there must be good bond from cement to pipe and cement to formation. Thus, if there is fast formation arrival there is good bond on both sides of cement. The problem arises when the formation arrival appears like pipe arrival. Look for clean GR (hard rock carbonates)earlier arrival times in VDL and travel time, , wavy appearance in VDL and lack of chevrons in VDL. 3’ amplitude may be high or low. Microannulus

Microannulus

Reduction in 3’ amplitude under pressure. Loss of pipe arrival in VDL under pressure Reduction in 2’ radial amplitudes under pressure

No chevrons present. Under good bond collars show straight-line collars patterns. Formation arrivals may be weak or not present at all.

Light Weight Cement - VDL exhibits a “straight line” collar effect with no chevron patterns. First arrival in VDL and 3’ Travel Time is pipe as cement does not fully attenuate signal. 3’ amplitude may baseline up to 10 mV (new 100% bond). Formation arrival may be weak if present.

Cased Hole Logging TCP and Conventional Perforating Swabbing Specialty Services

Microannulus - Micro-seperation of pipe from cement that reduces the cements ability to support the pipe in shear and thus allows for some pipe ring. To test for a microannulus, the pipe is logged under pressure to see a reduction in 3’ amplitude, loss of pipe arrival in VDL and improved radials. The presence of a microannulus indicates cement present. Brooks - 403.501.8474 Red Deer - 888.309.3055 Whitecourt - 780.778.4505 Grande Prairie - 780.538.1108