TU – PE 4063/6463 – Well Completion
Fall 2010
PE 4063 / 6463 – Well Completion CHAPTER 1 - Introduction
Schlumberger Oilfield Glossary: “The hardware used to optimize the production of hydrocarbons from the well. This may range from nothing but a packer on tubing above an openhole completion ("barefoot" completion), to a system of mechanical filtering elements outside of perforated pipe, to a fully automated measurement and control system that optimizes reservoir economics without human intervention (an "intelligent" completion).”
“A generic term used to describe the assembly of downhole tubulars and equipment required to enable safe and efficient production from an oil or gas well. The point at which the completion process begins may depend on the type and design of well. However, there are many options applied or actions performed during the construction phase of a well that have significant impact on the productivity of the well.”
Introduction
The word "completion" means the conclusion of a borehole that has just been drilled. Completion is, therefore, the link between drilling the wellbore and the production phase. Completion involves all of the operations designed to make the well produce, in particular connecting the borehole and the pay zone, treating the pay zone, equipping the well, putting it on stream and assessing it. Pay zone is the reservoir rocks which contain oil and/or gas that can be recovered. Generally speaking, certain measurement and maintenance operations in the well along with any workover jobs that might be required also come under the heading of completion are considered. Therefore, completion begins with well positioning and ends only at well abandonment. Whatever the operational entity in charge of well completion and workover, its actions are greatly influenced by the way the well has been designed and drilled and by the production problems the reservoir might cause. The "completion man" will therefore have to work in close cooperation with the "driller" (who may both work in one and the same department), and also with reservoir engineers and production technical staff.
Dr. Evren M. Ozbayoglu, Tel: 918-631 2972, e-mail:
[email protected]
Chapter-1, 1/21
TU – PE 4063/6463 – Well Completion
Fall 2010
After a well has been drilled, it must be properly completed before it can be put into production. A complex technology has evolved around the techniques and equipment developed for this purpose. Consequently, the selection of materials, equipment and techniques should only be made following a thorough investigation of the factors which are specific to the reservoir, wellbore and production system under study.
Thus, completion engineer should be in coordination of many different professionals. As seen from the following figure, the completion engineers should be in contact with drilling engineers, reservoir engineers, production engineers, geologists, etc. Therefore, completion process required a massive teamwork.
There are three basic requirements of any completion (in common with almost every oilfield product or service). A completion system must provide a means of oil or gas production (or injection) which is; i) Safe ii) Efficient iii) Economic
Current industry conditions may force operators to place undue emphasis on the economic requirement of completions. However, a non-optimized completion system may compromise Dr. Evren M. Ozbayoglu, Tel: 918-631 2972, e-mail:
[email protected]
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TU – PE 4063/6463 – Well Completion
Fall 2010
long-term company objectives. For example, if the company objective is to maximize the recoverable reserves of a reservoir or field, a poor or inappropriate completion design can seriously jeopardize achievement of the objective as the reservoir becomes depleted. In short, it is the technical efficiency of the entire completion system, viewed alongside the specific company objectives, which ultimately determines the completion configuration and equipment used.
Well completion processes extend far beyond the installation of wellbore tubulars and equipment. Installing and cementing the production casing or liner, as well as logging, perforating and testing are part of the completion process. In addition, complex wellhead equipment and processing or storage requirements effect the production of a well so may have some bearing on the design and configuration of the completion.
As the understanding of reservoir and production performance has evolved, so the systems and techniques put in place as part of the completion process. Early wells were drilled in very shallow reservoirs, which were sufficiently consolidated to prevent caving. As deeper wells were drilled, the problems associated with surface water prompted the use of a casing or conductor to isolate water and prevent caving of the wellbore. Further development of this process led to fully cased wellbores in which the interval of interest is selectively perforated. Modern completions are now commonly undertaken in deep, hot and difficult conditions. With the simultaneous improvement in seismic interpretation and drilling technology, wellbores can be precisely placed to optimize production and enable effective reservoir management. There are clear economic benefits to be gained from reducing the number of wellbores required for any reservoir development. However, fewer, but more efficient wellbores require a greater emphasis to be placed on the design, selection and installation of the completion equipment. Horizontal wellbores, and the technology associated with their completion are becoming common in many fields. Drilling extended reach wells often means that well servicing and intervention options are severely restricted, further emphasizing the importance of correct design and installation of the initial completion equipment. In all cases, achieving the completion objectives, and subsequent production targets are a result of careful planning and preparation.
Dr. Evren M. Ozbayoglu, Tel: 918-631 2972, e-mail:
[email protected]
Chapter-1, 3/21
TU – PE 4063/6463 – Well Completion
Fall 2010
The following figure shows the well cost analysis of a well drilled for 10,000 ft. It can be seen that, "completion equipment" accounted for approximately 10% of the total cost for the well. Overall approximate cost for such a well is estimated to be 2.5 MM $.
Site Preparation 2% Cementing 6%
Personnel Logistics 1% Other Rental Equipment 1% 2%
Camp 1% Mob/Demob 15%
Supervision 2%
Bits & Coring 6%
Casing 13%
Directional Services 8%
Drilling Rig 13%
Logging & Perforating 8% Completion Tubulars & Equipment 10%
Drilling Fluid 12%
Well Completion Planning
Planning a completion, from concept through to installation, is a complex process comprising several distinct phases. Many factors must be considered, although in most cases, a high proportion can be quickly resolved or disregarded. Ultimately, it is the predicted technical efficiency of a completion system, viewed alongside the company objectives, which will determine the configuration and components to be used.
Although many wells (and fields) may be similar, the success of each completion system should be closely based on the individual requirements of each well. Therefore, generic design or installation procedures should be carefully reviewed and amended as required. The economic impact of designing and installing non-optimized completions can be significant. Consequently the importance of completing a thorough design and engineering process must be stressed.
Dr. Evren M. Ozbayoglu, Tel: 918-631 2972, e-mail:
[email protected]
Chapter-1, 4/21
TU – PE 4063/6463 – Well Completion
Fall 2010
Delaying the commencement of the wells payout period is one example of how non-optimized completion design, or performance, can effect the achievement of objectives. However, while reducing installation cost and expediting start-up are important objectives, further reaching objectives, such as long-term profitability must not be ignored. A more complex and costly completion may provide a greater return over a longer period.
Principal phases of the general sequence in which completion design and installation factors typically studied can be summarized as follows: Establishing the objectives and design basis Determining the optimum well performance Establishing the conceptual completion designs Reviewing the strategy for life of the well and field Developing detailed completion design Planning of associated components, and service activities Preparation of offsite and onsite Installation Evaluation
Data Sources
In order to select the suitable completion type as well as conduct a proper completion design, information should be gathered from different possible sources. Following figure summarizes the sources that are used for this purpose.
Dr. Evren M. Ozbayoglu, Tel: 918-631 2972, e-mail:
[email protected]
Chapter-1, 5/21
TU – PE 4063/6463 – Well Completion
Fall 2010
Reservoir Parameters
The information about the reservoir can be obtained by formation and reservoir evaluation programs such as coring, testing and logging. Typically, such data will be integrated by reservoir engineers to compose a reservoir model. The reservoir structure, continuity and production drive mechanism are fundamental to the production process of any well. Frequently, assumptions are made of these factors, which later prove to be significant constraints on the performance of the completion system selected.
Physical characteristics of the reservoir, such as pressure and temperature, are used in describing reservoir and downhole conditions. The effects of temperature and pressure on many other factors can be significant. For example, corrosion rates, selection of seal materials and the properties of produced fluids are all affected by temperature and pressure. When investigating the reservoir rock characteristics, the principal concern is assessing formation behavior and reaction. This includes behavior and reaction to the drilling, production or stimulation treatments which
Dr. Evren M. Ozbayoglu, Tel: 918-631 2972, e-mail:
[email protected]
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TU – PE 4063/6463 – Well Completion
Fall 2010
may be required to fully exploit the potential of the reservoir. The formation structure and stability should be closely investigated to determine any requirement for stimulation or sand control treatment as part of the completion process. The reservoir characteristics effecting completion configuration or component selections are best summarized by reviewing the reservoir structure, continuity, drive mechanism and physical characteristics.
Reservoir Parameters Reservoir Boundaries o Structural traps o Stratographic traps o Unconformities o Permeability contrasts
Reservoir Structure o Continuity o Permeability barriers o Isotropy
Production Mechanism o Water drive o Solution gas o Gas cap o Combination o Injection o Artificial
Physical Parameters o Size o Shape o Height o Pressure
Dr. Evren M. Ozbayoglu, Tel: 918-631 2972, e-mail:
[email protected]
Chapter-1, 7/21
TU – PE 4063/6463 – Well Completion
Fall 2010
o Temperature
Rock Properties o Porosity o Permeability o Pore size distribution o Fluid saturation o Grain size and shape o Wettability
Rock Composition o Composition o Contamination o Clay content o Moveable fines o Cementaceous material o Scale forming materials
Reservoir pressure is the key parameter in the well's natural flow capability. If the reservoir pressure is or becomes insufficient to offset production pressure drawdown (particularly the hydrostatic pressure of the fluid column in the well and pressure losses), it is then necessary to install a suitable artificial lift system such as pumping the fluids or lightening them by gas injection in the lower part of the tubing (gas lift). If a reasonably accurate estimate of future requirements in this area can be made at the time of initial completion, an attempt is made to take them into consideration when completion equipment is chosen. Such a procedure can make later workover easier or unnecessary. The change in reservoir pressure is physically related to cumulative production (rather than directly to time) and to the drive mechanism(s) involved.
Dr. Evren M. Ozbayoglu, Tel: 918-631 2972, e-mail:
[email protected]
Chapter-1, 8/21
TU – PE 4063/6463 – Well Completion
Fall 2010
Injection wells may supplement the action of natural drive mechanisms such as one-phase expansion, solution gas drive, gas cap drive or water drive. The injected fluid maintains pressure (or slows down the pressure drop) and in addition flushes out the oil. Although the two functions cannot be dissociated in practice, one of them (maintaining pressure or oil flushing) can more particularly justify this type of well. Mostly water is injected, but gas may sometimes also have to be injected.
Rock characteristics and the type of reservoir fluids will directly influence completion, especially with respect to the well's flow capacity, the type of formation treatments that have to be considered and the production problems that have to be dealt with. Let us mention the following parameters in particular: The nature and composition of the rocks The degree of reservoir consolidation The extent of reservoir damage The temperature The fluid's viscosity The fluid's corrosive or toxic properties The fluid's tendency to emulsify or lay down deposits
Dr. Evren M. Ozbayoglu, Tel: 918-631 2972, e-mail:
[email protected]
Chapter-1, 9/21
TU – PE 4063/6463 – Well Completion
Fall 2010
Produced Fluid Characteristics
Two conditions, relating to the chemical properties of the produced fluid most affect the physical qualities of completion components and materials. These are chemical deposition (scale, asphaltenes etc.) and chemical corrosion (weight loss and material degradation). The ability of the reservoir fluid to flow through the completion tubulars and equipment, including the wellhead and surface production facilities, must be assessed. For example, as the temperature and pressure of the fluid changes, the viscosity may rise or wax may be deposited. Both conditions may place unacceptable backpressure, therefore causes a dramatic reduction the efficiency of the completion system. While the downhole conditions contributing to these factors may occur over the lifetime of the well, consideration must be made at the time the completion components are being selected. Cost effective completion designs generally utilize the minimum acceptable components of an appropriate material. In many cases, reservoir and downhole conditions will change during the period of production. The resulting possibility of rendering the completion design or material unsuitable should be considered during the selection process.
Produced Fluid Characteristics Physical Properties o Oil density o Gas gravity o Viscosity o Pour point o Gas-oil ratio o Water-oil ratio
Chemical Properties o Composition o Wax content o Asphaltenes
Dr. Evren M. Ozbayoglu, Tel: 918-631 2972, e-mail:
[email protected]
Chapter-1, 10/21
TU – PE 4063/6463 – Well Completion
Fall 2010
o Corrosive agents o Toxic components o Scale
The existence of interfaces between fluids, in particular when they are not controlled, causes a decrease in target fluid productivity at the same time as an increase in unwanted fluids (water and gas for an oil reservoir, water for a gas reservoir). Additionally, since these unwanted fluids get into the well, they must be brought up to the surface before they can be disposed of. They, therefore, not only penalize well productivity, but also instrumental in decreasing reservoir pressure. This interface problem is more particularly critical when the viscosity of the target fluid is more or less the same (light oil and water) or even much greater (heavy oil and water, oil and gas) than that of the unwanted fluid. The interfaces vary with time, for example locally around a well, by a suction phenomenon causing a cone (coning) which is related to the withdrawal rate. They can also vary throughout the reservoir depending on the amount of fluid that has already been withdrawn, allowing a gas cap or an aquifer, etc. to expand.
Coning; a) stable cone, b) water encroachment
Wellbore Construction
Wellbore construction factors can be categorized in the following phases; i) Drilling – The processes required to efficiently drill to and through the reservoir
Dr. Evren M. Ozbayoglu, Tel: 918-631 2972, e-mail:
[email protected]
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TU – PE 4063/6463 – Well Completion
Fall 2010
ii) Coring and testing – The acquisition of wellbore survey and reservoir test data used to identify completion design constraints iii) Pre completion stimulation or treatment – final preparation of the wellbore through the zone of interest for the completion installation phase.
It is an obvious requirement that the drilling program must be designed and completed within the scope and limits determined by the completion design criteria. Most obvious are the dimensional requirements determined by the selected completion tubulars and components. For example, if a multiple string completion is to be selected, an adequate size of production casing (and consequently hole size) must be installed. Similarly, the wellbore deviation or profile can have a significant impact. Drilling and associated operations, e.g., cementing, performed in the pay zone must be completed with extra vigilance. It is becoming increasingly accepted that the prevention of formation damage is easier, and much more cost effective, than the cure. Fluids used to drill, cement or service the pay zone should be closely scrutinized and selected to minimize the likelihood of formation damage. Similarly, the acquisition of accurate data relating to the pay zone is important. The basis of several major decisions concerning the technical feasibility and economic viability of possible completion systems will rest on the data obtained at this time. A pre-completion stimulation treatment is frequently conducted. This is often part of the evaluation process in a test treat-test program in which the response of the reservoir formation to a stimulation treatment can be assessed.
Wellbore Construction Drilling o Hole size o Depth o Deviation o Well path o Formation damage
Evaluation o Logging
Dr. Evren M. Ozbayoglu, Tel: 918-631 2972, e-mail:
[email protected]
Chapter-1, 12/21
TU – PE 4063/6463 – Well Completion
Fall 2010
o Coring o Testing o Fluid sampling
Pre-completion o Casing schedules o Primary cementing o Pre-completion stimulation
For a development well, the most important thing is to have a borehole with a big enough diameter to accommodate the equipment that will be installed in it. In contrast, when the pay zone drilling diameter is increased above and beyond what is required for the production equipment, it does not boost the well's flow capacity very much. Since the diameter depends on the initial drilling program, this explains the saying that is sometimes used: "Completion begins with the first turn of the bit". As a result, the drilling and casing program must be optimized taking both drilling and production requirements into account, without losing sight of the flow capacity versus investment criterion.
From the time the drilling bit reaches the top of the reservoir and during all later operations, reservoir conditions are disturbed. Because of this, problems may arise in putting the well on stream. In particular, the pay zone may be damaged by the fluids used in the well (drilling fluid, cement slurry, etc.), and this means reduced productivity. Depending on the case, productivity can be restored relatively easily (generally true for carbonate formations: limestone, dolomites, etc.). It may prove to be difficult or even impossible for sandstone formations. In any case, it requires costly treatment in terms of rig time and of the treatment itself. Formation damage should not be seen simply in terms of the cure but also in terms of prevention, especially when formation plugging is very expensive or impossible to solve. As a result, the choice of fluid used to drill the pay zone is critical.
Dr. Evren M. Ozbayoglu, Tel: 918-631 2972, e-mail:
[email protected]
Chapter-1, 13/21
TU – PE 4063/6463 – Well Completion
Fall 2010
Completion Assembly Installation
This stages marks the beginning of what is commonly perceived as the “completion program”. Considerable preparation, evaluation and design work has been completed before the completion tubulars and components are selected. With all design data gathered and verified, the completion component selection, assembly and installation process commences. This phase carries obvious importance since the overall efficiency of the completion system depends on proper selection and installation of components. A “visionary” approach is necessary since the influence of all factors must be considered at this stage, i.e., factors resulting from previous operations or events, plus an allowance, or contingency, for factors which are likely or liable to affect the completion system performance in the future. The correct assembly and installation of components in the wellbore is as critical as the selection process by which they are chosen. This is typically a time at which many people and resources are brought together to perform the operation. In general, completion components are broadly categorized as follows i) Primary completion, components ii) Auxiliary completion components.
Primary completion components are considered essential for the completion to function safely as designed. Such components include the wellhead, tubing string, safety valves and packers. In special applications, e.g., artificial lift, the components necessary to enable the completion system to function as designed will normally be considered primary components. Auxiliary completion components enable a higher level of control or flexibility for the completion system. For example, the installation of nipples and flow control devices can allow improved control. Several types of device, with varying degrees of importance, can be installed to permit greater flexibility of the completion. While this is generally viewed as beneficial, a complex completion will often be more vulnerable to problems or failure, e.g., due to leakage. The desire for flexibility in a completion system stems from the changing conditions over the lifetime of a well, field or reservoir. For example, as the reservoir pressure depletes, gas injection via a side-pocket mandrel may be necessary to maintain optimized production levels.
Dr. Evren M. Ozbayoglu, Tel: 918-631 2972, e-mail:
[email protected]
Chapter-1, 14/21
TU – PE 4063/6463 – Well Completion
Fall 2010
Completion fluids often require special mixing and handling procedures, since; i) the level quality control exercised on density and cleanliness is high ii) completion fluids are often formulated with dangerous brines and inhibitors.
The ultimate selection of completion components and fluids should generally be made to provide a balance between flexibility and simplicity.
Completion Assembly Installation Primary Components o Wellhead o Christmas tree o Tubing o Packer o Safety valve
Completion Fluids o Completion fluid o Packer fluid o Perforating fluid o Kick-off fluid
Auxiliary Components o Circulating devices o Nipples o Flow couplings o Injection mandrels o Tubing seal assembly
Dr. Evren M. Ozbayoglu, Tel: 918-631 2972, e-mail:
[email protected]
Chapter-1, 15/21
TU – PE 4063/6463 – Well Completion
Fall 2010
Initiating Production
The three stages associated with this phase of the completion process include; i) Kick-off ii) Clean up iii) Stimulation
The process of initiating flow and establishing communication between the reservoir and the wellbore is obviously closely associated with perforating operations. If the well is to be perforated overbalanced, then the flow initiation and clean up program may be dealt with in separate procedures. However, if the well is perforated in an underbalanced condition, the flow initiation and clean up procedures must commence immediately upon perforation. While the reservoir/wellbore pressure differential may be sufficient to provide an underbalance at time of perforation, the reservoir pressure may be insufficient to cause the well to flow after the pressure has equalized. Adequate reservoir pressure must exist to displace the fluids from within the production tubing if the well is to flow unaided. Should the reservoir pressure be insufficient to achieve this, measures must be taken to lighten the fluid column - typically by gas lifting or circulating less dense fluid. The preparations for these eventualities are part of the completion design process. The flowrates and pressures used to exercise control during the clean up period are intended to maximize the return of drilling or completion fluids and debris. This controlled backflush of perforating debris or filtrate also enables surface production facilities to reach stable conditions gradually. In some completion designs, an initial stimulation treatment may be conducted at this stage. An acid wash or soak placed over the perforations has proved effective in some conditions. However, as underbalanced perforating becomes more popular, the need and opportunity for this type of treatment has diminished.
Production initialization Inducing Flow o Gas lift o Nitrogen kick-off o Light-fluid circulation
Dr. Evren M. Ozbayoglu, Tel: 918-631 2972, e-mail:
[email protected]
Chapter-1, 16/21
TU – PE 4063/6463 – Well Completion
Fall 2010
o Using completion components
Clean-up Program o Initial flowrate and rate of increase o Evaluation program o Test-treat-test
Stimulation
There are four general categories of stimulation treatment which may be considered necessary during the process of completing a well i) Wellbore cleanup ii) Perforation washing or opening iii) Matrix treatment of the near wellbore area iv) Hydraulic fracturing. Wellbore clean up will not normally be required with new completions.
However, in wells which are to be reperforated or in which a new pay zone is to be opened, a well bore clean up treatment may be appropriate. There are various perforation treatments which may be associated with new or re-completion operations. Perforating acids and treatment fluids are designed to be placed across the interval to be perforated before the guns are fired. Used in overbalanced perforating applications, the perforating acid or fluid reduces the damage resulting from the perforating operation. Perforation washing is an attempt to ensure that as many perforations as possible are contributing to the flow from the reservoir. Rock compaction, mud and cement filtrate and perforation debris have been identified as types of damage, which will limit the flow capacity of a perforation, and therefore completion efficiency. If the objective of the treatment is to remove damage in or around the perforation, simply soaking acid across the interval is unlikely to be adequate. The treatment fluid must penetrate and flow through the perforation to be effective. In which case all the precautions associated with a matrix treatment must be exercised to avoid causing further damage by inappropriate fluid selection. Matrix treatment of the near wellbore area may be designed to remove or by-pass the damage. Hydraulic
Dr. Evren M. Ozbayoglu, Tel: 918-631 2972, e-mail:
[email protected]
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TU – PE 4063/6463 – Well Completion
Fall 2010
fracturing treatments provide a high conductivity channel through any damaged area and extending into the reservoir.
Stimulation Wellbore and Perforations o Wellbore clean-up o Perforating acid o Perforation wash
Near Wellbore and Reservoir Matrix o Matrix acidizing o Hydraulic fracturing o Non-acid treatments
Well Service and Maintenance Requirements
The term “well servicing” is used to describe a wide range of activities including i) Routine monitoring ii) Wellhead and flowline servicing iii) Minor workovers (thru-tubing) iv) Major workovers (tubing pulled) v) Emergency response and containment.
Well service or maintenance preferences and requirements must be considered during the completion design process. With more complex completion systems, the availability and response of service and support systems must also be considered. Wellbore geometry and completion dimensions determine the limitations of conventional slickline, wireline, coiled tubing or snubbing services in any application.
Dr. Evren M. Ozbayoglu, Tel: 918-631 2972, e-mail:
[email protected]
Chapter-1, 18/21
TU – PE 4063/6463 – Well Completion
Fall 2010
Well Service and Workover Completion System Function o Well testing and routine monitoring o Emergency kill and containment
Light Service Units o Slickline o Electric wireline o Coiled tubing o Snubbing
Heavy Workover Units o Drilling rig o Workover rig o Combined coiled tubing and snubbing unit
Logistics
Restraints imposed by logistic or location driven criteria often compromise the basic “cost effective” requirement of a completion system. Special safety and contingency precautions or facilities are associated with certain locations, e.g., offshore and subsea.
Logistics Surface Facilities o Separator capacity o Export capability o Operational flexibility o Disposal facility
Dr. Evren M. Ozbayoglu, Tel: 918-631 2972, e-mail:
[email protected]
Chapter-1, 19/21
TU – PE 4063/6463 – Well Completion
Fall 2010
Location o Access to well o Weather conditions o Environmental constraints o Proximity of neighboring interests
How Completion is Designed
The Company’s operations management and the reservoir engineering department generally decide the main purposes of a well; For exploration and appraisal wells which mainly involves the level(s) that are to be tested, and the type and duration of the tests that are to be run. For development wells which basically involves the level(s) that are to be produced. The production or injection profile required for the wells.
Based on the above, particularly for development wells, the problem is to design the best possible completion in order to; Optimize productivity or injectivity performance during the well's complete lifetime make sure that the field is produced reliably and safely Optimize the implementation of an artificial lift process Optimize equipment lifetime Make it possible to change some or all of the well's equipment at a later date without too much difficulty so that it can be adapted to future operating conditions Minimize initial investment, operating costs and the cost of any workover jobs.
This may mean a compromise in the drilling and casing program or in operating conditions or even that the objectives have to be modified if they prove to be unattainable. The data required to set up a completion system are very numerous. Some of the most important constraints and parameters are listed below; Local constraints (regulations, environment, etc.) The type of effluents and their characteristics
Dr. Evren M. Ozbayoglu, Tel: 918-631 2972, e-mail:
[email protected]
Chapter-1, 20/21
TU – PE 4063/6463 – Well Completion
Fall 2010
The reservoir and its petrophysical characteristics The number of producing formations, each one's expected productivity and the interfaces The available diameter and the borehole profile Whether it is necessary to proceed to additional operations (well stimulation, sand control, etc.) Whether it is necessary to implement techniques to maintain reservoir pressure (water, gas, solvent or miscible product injection) or to lift the effluents artificially (gas lift, pumping, nitrogen or carbon dioxide injection) immediately or at a later date The eventuality of having to do any work on the pressurized well during the production phase by wireline, or with a concentric tubular (coiled tubing or snubbing)
Completion design is based on this body of data, so every effort must be made to be sure no important point has been disregarded, since incomplete or wrong data might lead to poor design. The job is not an easy one since; These data are very numerous and may be interrelated. Some of them are not very accurately known when completion is designed (sometimes not even when completion is being carried out). Some of them are contradictory. Some of them are mandatory, while others can be subject to compromise.
Dr. Evren M. Ozbayoglu, Tel: 918-631 2972, e-mail:
[email protected]
Chapter-1, 21/21
