bluuebunny/crossref_metadata_2025 huggingface dataset:
Economics of Coalbed Methane Field Development: A Case Study of Jatibarang Field
Authors: Nugroho Wisnu
Published: December 2007

Coalbed methane is a new energy resource that has not been developed in Indonesia. The reserve is estimated about 213 Tcf and spread over 16 basins. The utilization of this new energy resource will undoubtly contribute the industrial development in the country. This paper focuses on the technical and economic aspects of coalbed production in Jatibarang field, West Java. The methane reserve in this West Java area is 21 Tcf, and the location is quite strategic due to its proximity to the highly viable market of growing industrial nearby area. This paper presents a proposal of CBM development in Jatibarang field. The result shows a very lucrative return for the investment on the project based on production sharing agreement.
Why Control Cement Slurry Density?
Authors: Allen T. E. , Sands F. L.
Published: December 2007

The well cementation design process includes slurry design, spacer design, hole conditioning program design, casing attachments selection, and placement procedure design. This paper is concerned with slurry design and more particularly, the effects of deviations in mixed slurry density from the design point. Concern over these effects has been increasing in recent years. In 1987 an API Task Group in the Eastern Hemisphere Cementing formed a work group to study "the effect of poor density control on cement slurry properties " This group also investigated measurement and control of density. There were wide differences of opinion as to how well density was being controlled in the field and also what was necessary. Additional data and analysis will be presented which will help clarify some of the density slurry property relationships and therefore provide additional means to make rational decisions relative to density control specifications.

Density as a slurry property is significant to wellbore hydrostatic pressure. However, deviations from design density may cause changes in all other slurry properties which may or may not cause future well problems. The relationships defining slurry property dependence on slurry density are important when establishing meaningful density control limits. However, closer limits generally mean higher mixing system and operation costs. Thus, there is an economic motivation for understanding how deviations effect slurry properties. The knowledge of the cost to obtain a specific density tolerance can be weighed against its benefit. More appropriate specifications can be developed to match job requirements. The end result could be a change in the way slurry properties are specified.

Knowledge of the sensitivity of the designed slurry to density variation will make selection of surface mixing equipment more meaningful. Batch mixing gives the ultimate in control but cost more. Offshore, batch mixers take up valuable rig space and add weight.
Management Systems in Production Operations
Authors: Walters K. B. , Henderson Grahaeme
Published: December 2007

The Cullen Enquiry into the Piper Alpha disaster in the U.K North Sea recommended that an operator should formally present it's Company Management System and demonstrate how safety is achieved throughout the life cycle of a platform, from design through Operation to abandonment.

Brunei Shell Petroleum has prepared a corporate level Safety Management System. As part of Safety Case work, the corporate System is being extended to include the development of specific Management Systems with particular emphasis on offshore production operations involving integrated oil and gas facilities. This paper will describe the development of Management Systems, which includes an intensive Business Process Analysis and will comment upon it's applicability and relationship to ISO 9000.

The paper will further describe the applicability and benefits of Management Systems and offer guidance on required effort. The paper will conclude that development of structured Management Systems for safety critical business processes is worthwhile but prioritisation of effort will be necessary. As such the full adoption of Management Systems will be directional in nature.
Improvements in MWD Telemetry: "The Right Data at the Right Time"
Authors: Montaron B. A. , Hache J- M. D. , Voisin Bernard
Published: December 2007

The 1991 SPE Forum on MWD concluded that current telemetry data rate via mud pulse was inadequate. This paper addresses this issue.

New downhole sensors have been continuously added to MWD Systems and have joined the directional measurements and simple formation evaluation tools commercialized in the seventies. As a result, MWD Systems have been challenged to transmit an increasing amount of data to the surface. Most commercial Systems use the mud column as the transmission channel. MWD telemetry is revisited, analyzing in detail the factors affecting the transmission through the mud. Noise sources and new techniques to minimize interference are described and field examples are presented. The maximum data rate achievable through the mud channel is evaluated, and is compared with current and future needs for real-time use. Data compression techniques are discussed. The impact of data rates on log quality, for a given drilling rate of penetration, is illustrated through field examples at different data rates. New techniques of quality checks on the data which allow quantification of the accuracy of the transmission are described with Statistical test results. Examples of current MWD telemetry Systems covering the range of data rates available today (from 0.5 bits/s to more than 5 bits/s) are presented. The use of microprocessors in the new generation of MWD tools is shown to have impacted dramatically the reliability of the transmission, both in quality and versatility with direct benefits to the end user of the data.
Review of Techniques for the Interpretation and Evaluation of Thin Sand Sequences
Authors: Forsyth David , Nawawi Haji , Ho T. C.
Published: December 2007

Th is paper describes a review conducted on data from seiected wells in a mature field with the objective of establishing techniques for the evaluation oflaminated sand sequences and assessing the impact of including such sequences in the reserves of the field. The field is sėtina deltaic environment and has been ander development for twenty years with some three hundred wells having already been drilled. Recent core data have revealed that quite some potential reserves may be contained in thin sand/ laminated sand sequences. Conventional log data have insufficient vertical resolution to resolve individual sands and consequently the contribution to the reserves of these intervals has been dijjficult to assess. Recent advances in logging technology and in data Processing have improved this Situation. This review concentrates on assessing the ęffectiveness of these new techniques. The Integration of core and produetion data with imaging techniques are presented. The results show that such intervals can be evaluated although ultimately the contribution to STOnP is also influenced by other factors not directly measurable in the borehole.
Results of Trial Using Silicon Activation Gravelpack Evaluation Tool (SGPT) in Bokor
Authors: Yahia Ziadil , Elshahawi H. M. R.
Published: December 2007

Conventional nuclear fluid density gravelpack evaluation tool (GPPT) was found to cause misinterpretation when run in well containing fluid of different densities. As a result an alternative tool called silicon activation gravelpack tool (SGPT) was field tested. The principle of the tool is based on detection of activated gamma ray which is produced when silicon atoms are made unstable by striking with fast neutrons.

The trials were carried out in 3 wells in Bokor. In order to get conclusive results, GPPT and PLT were also run in these wells and the results compared. It was found that in wells with single phase fluid, the SGPT results were in agreement with the GPPT′s. When logging from water to oil, both tools were affected but SGPT was less affected than GPPT.

The effect of water on GPPT was almost the same as the effect due to top of gravel. For SGPT, the effect due to gravel was more pronounced compared to effect due to water. When logging from oil to gas, SGPT didn't show any shift in readings whereas the GPPT was badly affected.

In conclusion, SGPT was found to be more reliable than GPPT for evaluating gravelpacks when there were more than one fluid densities in the wellbore.
The Use of a Log-Derived Formation Strength Index for Gravel Pack Decision Making in the Rasau Field
Authors: Clayton F. M. , Van Haeringen Arie
Published: December 2007

It has been proposed in the literature that formation strength could be predicted using the bulk density and sonic transit time derived from wireline logs. Experimental work was therefore carried out which gave a correlation between the density/sonic readings from logs and the onset of sand production. The density/sonic relation is termed the Formation Strength Index (FSI).

The FSI has been used in the Rasau Field, Brunei, in combination with expected production conditions, to predict the onset of future sand production thus allowing it to be used to assess the requirement for sand control.

To date, twelve gravel packs have been avoided. This has resulted in a cost saving of some US$ 3 mln and the avoidance of the normal gravel pack impairment.
Field Tests of a Slim Carbon/Oxygen Tool for Reservoir Saturation Monitoring
Authors: Stoller Christian , Scott H. D. , Plasek R. E. , Lucas A. J. , Adolph R. A.
Published: December 2007

Oil production from many major producing reservoirs is now maintained by water injection programs. The resulting mixed and often very low-salinity formation water presents a serious problem when monitoring water saturation with traditional pulsed neutron capture (PNC) tools. A slim carbon/oxygen (CAD) pulsed neutron tool tested recently in many regions around the world addresses the problems encountered in low- and mixed-salinity environments. The tool's dual y-ray detectors and flexible neutron burst timing allow it to be used for carbon/oxygen logging and, in a separate pass, for PNC logging. New detector and accelerator technologies as well as advanced data processing allow logging speeds that meet or exceed those of traditional, large, single-detector C/O tools.
Application of Deuterium Tracer in Estimating Native Water Saturation in the Gyda Field
Authors: Fjerstad P. A. , Thoreby Helge , Pallatt Nadia , Stockden Ian
Published: December 2007

An independent method for estimating initial reservoir water saturation in the Gyda Field has been investigated. Further application of recent tracer technology was used in describing the initial fluid saturations in the reservoir. This was achieved by using a deuterium tracer technique to quantify aqueous mud-filtrate invasion to core and which enabled ‘native’ water saturation determinations to be made. The volume of extracted core-water was translated into native reservoir water saturations after correcting for mud-filtrate invasion, reservoir overburden, pressure and temperature effects.

The technique is an alternative method for obtaining initial water saturation data. The proposed proved method could be replaced by empirical determinations of water saturation from wireline responses where exponents are derived from special core analysis data. The tracer technique proposed has particular application not only to thick bedded sands, carbonates and conglomerates, but also to thin bedded zones where logging resolution is poor. The method has also particular application in low resistivity pay sands in which large volumes of immobile capillary water occur.
Channel Detection Using Pulsed Neutron Logging in a Borax Solution
Authors: Sommer F. S. , Jenkins D. P.
Published: December 2007

The PNL/Borax log was designed as a replacement for temperature and radioactive tracer logs in identifying channels in the cement sheath surrounding the casing in production or injection wells. This isnl the only application of the log. Because of the correction for thermal neutron diffusion, it can be used to differentiate between a channel and other mechanisms of fluid movement, such as a leaking packer, leaking squeezed perforations, and gas migration under an impermeable barrier within the formation. These added capabilities can result in a better diagnosis of the well condition. With the downhole processes pinpointed, the proper kind of remedial wellwork can be recommended to optimize the performance of the well.

The PNL/Borax log has been successfully used to diagnose channels (or lack of channels) in dozens of producers in Alaska's Prudhoe Bay oil field, and has been run with mixed results in injectors. It has also been used to successfully distinguish between leaking packers and channels. In addition, the borax tracer has been found to be safe to wellsite personnel, and can be produced back out of the formation to minimize impacts of future neutron logging operations. This paper presents the basic theory behind PNL/Borax logging and provides field examples of its use in producers and injectors.
Analysis of Pressure and Pressure Derivatives Without Type-Curve Matching: I—Skin and Wellbore Storage
Authors: Tiab Djebbar
Published: December 2007

The current type-curve matching technique is essentially a trial-and-error procedure without any independent and accurate way of checking the validity of the end results.

This paper introduces a new technique for interpreting pressure tests. This technique uses log-log plots of the pressure and pressure derivative versus time to calculate reservoir and well parameters WITHOUT type-curve matching. This paper concentrates on the interpretation of pressure tests in which wellbore storage and skin are present. The technique essentially consists of obtaining characteristic points of intersection of various straight line portions of the pressure and pressure derivative curve, slopes and starting times of these straight lines. These points, slopes and times are then used with appropriate equations to solve directly for permeability, wellbore storage and skin. A step-by-step procedure for calculating these parameters without type-curve matching for five different cases is included in the paper.

The most important aspect of this new technique is undoubtedly its accuracy because it uses exact analytical solutions to calculate permeability, skin, and wellbore storage. The second most important feature of this new technique is that it is verifiable. Any two parameters calculated from two independent equations corresponding to two different portions of the pressure derivative curve are verified by a third equation which corresponds to a known and unique point relating the two parameters. The proposed technique is applicable to the interpretation of pressure buildup and drawdown tests. This technique is illustrated by several numerical examples.
Technique Improves Openhole Gravel Pack
Authors: Wilton B. S. , Swain R. S. , Tuttle J. D. , Harkey Dee
Published: December 2007

A new technique for open hole circulation gravel packs was implemented on three wells in the Tejon Field, Kern County, California that improved pack placement procedures and resulted in reduced completed well costs. The following contributed to overall well performance: (1) fluid selection to match reservoir characteristics, (2) polymer selection to stabilize the wellbore and place the pack effectively, (3) compatibility and displacement of underreaming and gravel pack fluids, (4) shearing and filtering techniques to minimize microgel effects and (5) breaker selection to eliminate polymer effects in a timely manner. Two smectite rich production zones having a combined length in excess of 500 feet were packed as a single stage circulation pack using an inhibitive carrier fluid viscosified with a clarified xanthan gum biopolymer. The clarified xanthan gum fluid also proved to be superior in maintaining a stable wellbore in which to run the slotted liner. The gravel pack fluid was continuously filtered through diatomaceous earth and 10 micron absolute cartridge filters throughout the circulation pack procedure. Photomicrographs and gravimetric analysis of the fluid illustrate the effectiveness of the shearing and filtering procedure before and during pack placement.

Improved initial production rates were realized by implementing this cost effective procedure.
Reverse Circulation of Cement on Primary Jobs Increases Cement Column Height Across Weak Formations
Authors: Griffith J. E. , Nix D. Q. , Boe G. A.
Published: December 2007

This paper outlines advantages of reverse circulation of cement to reduce the equivalent circulating density (ECD) such that weak formations may not fracture during the primary cementing procedure. A typical operation is outlined for utilizing the method in the Appendix. Tests with large-scale geometries showing no detrimental effect on displacement efficiency are discussed.
Field Study of Efficiencies Between Progressing Cavity, Reciprocating, and Electric Submersible Pumps
Authors: Saveth K. J.
Published: December 2007

With operating costs playing a larger and larger role in the economics of producing a well, optimizing equipment selection by means of an efficient artificial lift system is critical in reducing operating costs for a given field.

Six wells in Carter County, Oklahoma utilizing three different methods of artificial lift were looked at to compare overall system efficiencies between each method. Progressing cavity, reciprocating, and electric submersible pumps were compared on a per barrel of fluid produced basis and the electrical power usage converted to kw-hr/hr.
Fishing With Coiled Tubing
Authors: Hilts R. L. , Fowler S. H. , Pleasants C. W.
Published: December 2007

Improved coiled tubing (CT) technology, development of specially-designed hydraulically-actuated service tools, and increased emphasis on cost efficiency have made coiled tubing a viable option for many fishing jobs. Before the emergence of coiled tubing fishing technology, traditional service procedures included use of wireline to retrieve fish from oil and gas wells. If wireline was unsuccessful, a rig or hydraulic workover (snubbing) unit had to work over the well and remove the fish.

This paper addresses the successful use of CT in fishing operations. The capability of CT to circulate fluids at the fish and generate high downhole forces enables the retrieval of fish in situations that would not be possible or cost effective by other service options. CT fishing can be performed under pressure on live, highly-deviated or horizontal wells; the job can be completed and the well returned to production within 1 to 3 days for only a fraction of the cost of a workover.

The paper will describe the tools, their capabilities, and service techniques currently in use for CT fishing operations as well as new equipment being developed. Data from several case histories will be used to provide considerations, surface rig-up, and job limitations.
Low-Density Acid-Removable Cement as a Solution for Lost Circulation Across Producing Formations
Authors: Bour D. L. , Vinson E. F. , Totten P. L. , Waheed Arshad
Published: December 2007

Lost return problems have been typically solved with lost circulation pills containing plugging materials like mica, cellophane, and walnut hulls. However, should lost returns occur across potential producing formations, use of such materials may result in permanent damage to these zones. Dislodgment of the plugging material can result in resumption of lost returns. This paper describes the laboratory development of a foamed fluid system that can function to solve the problem of lost circulation. Foaming offers the operator an option to prepare a fluid with densities below that obtainable even with water. Additionally, this system possesses acid solubility, thereby minimizing damage to potential producing formations. Laboratory slurry property data such as thickening time, compressive strength, and acid reaction rates are provided.

In addition to lost circulation, the foamed acid soluble cement system has application in both oil and gas wells as a temporary plugging material. Potential field applications of acid soluble cement in these areas are discussed.
Practical Horizontal Cementing Today
Authors: Kettl F. C. , Edwards M. G. , Covington R. L.
Published: December 2007

Horizontal wells present an effective method to maximize production potential and reduce development costs of some oil and gas fields. The ability to predict induced fracture direction with reasonable accuracy can allow the operator to drill in the direction considered most profitable.1 Ideally the well would have extended reach in the proper direction through a stable, fractured formation, would not require stimulation, and would not be subject to the production problems usually encountered in the life of a field. Since horizontal wells are drilled in a variety of formations, operators are experiencing the normal well problems and are finding stimulation and control methods useful for production improvement. This paper will examine problems associated with cementing of horizontal sections and the recent technology advancements that may be applied to help assure a competent annular hydraulic seal.

Conventional cemented completions have not been used extensively in horizontal wells since some operators lack confidence in the technology that is available. Problems have been perceived in managing cuttings transport, pipe centralization, effective mud displacement, cement free-water control, and effective placement of a cement seal around the casing. These problems do exist and corrective techniques are complicated by highly deviated wellbores, but technology advances have been made to address horizontal conditions. Proper cementing may continue to provide an economical hydraulic seal for zonal or wellbore segment isolation so necessary to effective stimulation and work-over operations.

The use of advanced technology often requires extensive pre-planning and includes the necessity to properly communicate the benefits to field operations personnel to assure the proper implementation of new or different techniques or materials. Little good will come from the best ideas without proper follow-through during application.
Stage Cementer With Integral Inflatable Packer Collar
Authors: Borges J. F. , Turki W. H. , Giroux R. L. , Stepp L. W.
Published: December 2007

Lost circulation during primary cementing is a common problem in the Middle East area. To overcome this problem, operators have commonly used a stage tool with an integral packer element. Often, these elements are inflatable, since most mechanical packer elements have limited differential pressure capabilities.

To improve and simplify the operation of stage cementing integral inflatable packer collars (SCIIPCs), designers have developed an opening system that has no moving parts. This system, featuring replaceable rapture disks, has been successfully tested in the US and Middle East

This paper describes the SCIIPC itself, the lab tests required before it could be ran, and presents test results. The paper also presents actual case histories featuring the new system during initial field testing.
Performance Prediction of Horizontal Wells Utilized To Alleviate Water Slumping
Authors: Kader M. S. Abdel , Hafez H. H. , Badaam H. S.
Published: December 2007

Within ADCO, horizontal drilling has been used to reduce the effects of water slumping between pseudo reservoirs resulting in reduced water cut and increased productivity. This paper discusses the use of finite element models to predict the performance of two such horizontal wells and compares predictions with actual performance.

The reservoir discussed is comprised of two pseudoreservoirs, both pressure supported by peripheral water injection. Water advance in the upper pseudo-reservoir has been faster as its permeability is greater than that of the lower pseudo-reservoir. Local pressure drawdown effects, have resulted in water slumping from the wet upper pseudo-reservoir to the dry lower pseudo- reservoir.

To alleviate water slumping and increase well productivity, two wells were recompleted with short radius horizontal holes of 240 and 850 feet lengths. This resulted in reduction of water cuts from 20 % to less than 1% in one well and 4% in the other and significant increases in well productivity.

A previous paper discussed the element model construction, history matching and performance prediction for the first well. This paper compares the performance predictions with actual well performance and discusses the extended application of the model to the second well.
Case Studies of Horizontal Well Design and Production Forecast
Authors: Wang Ben , Markitell B. N. , Huang W. S.
Published: December 2007

This paper presents the observed and predicted performance of horizontal wells in four fields: (1) heavy oil reservoir - to increase productivity and reduce gas coning, (2) thin oil column with gas cap and bottom water - to minimize gas and water coning, (3) waterflood in a tight oil sandstone reservoir - to increase injectivity /productivity, areal sweep efficiency, and improve pressure maintenance (4) gas reservoir with bottom water - to increase productivity and minimize water coning.

A special program, named "HVWELL", was used in these studies to predict horizontal and vertical well production performance. HVWELL requires minimal reservoir and fluid information to create a complete input dataset for running a finite difference simulator. It is equipped with a unique automatic grid set-up option to create correct grid geometry to model various horizontal well lengths and well locations. The geometries relate to GOC/WOC, and hydraulic fractures perpendicular to the horizontal wellbore. The options can greatly minimize the input errors and reduce grid requirements by simulating a symmetrical element instead of a full pattern. HVWELL not only calculates well productivities, but also predicts 3-D, 3-P coning behavior for either vertical or horizontal wells. Short summary and graphical outputs are automatically generated for each run.

The horizontal well design and production predictions using HVWELL will be discussed in detail, and compared to field data for each case.
Horizontal Well Design in Wafra Field, Ratawi Oolite Reservoir
Authors: Menouar Habib , Huang W. S.
Published: December 2007

This paper presents the selection and design procedures for a side-tracked horizontal well in this semi-depleted reservoir. A commercially available black oil simulator was modified to account for the horizontal well simulation. After the pressure and production history match of the 40-year period, horizontal well production forecast was made.

Different horizontal well lengths, positions and bottomhole flowing pressures were used to study the production performance. Production rates, cumulative oil production and water oil ratios are resulting parameters in selecting the most suitable scenarios for decreasing pressure drawdown, and possibly improving the recoverable reserves.

Results indicate that: A 2000-foot horizontal well completed in the upper layers with maximum stand off from the water-oil contact would produce almost seven times more cumulative oil in 5 years than the vertical well in the same location. The potential starting oil production rate of this horizontal well is eight times that of the vertical well; in actual operation, we would limit pump sizes to produce the oil at less than the maximum capacity calculated.A 2000-foot horizontal well completed in the zone closer to the oil-water contact would lead to less oil and more water production.When the length of the horizontal well is increased to 3000 feet, the five-year cumulative oil production is increased by 15%, and more importantly, the cumulative water production amounts to only one quarter of that of the 2000-foot case. This is the recommended case for drilling a horizontal side track for this well.
Southern Arabian Basin Oil Habitat: Seals and Gathering Areas
Authors: Pierce W. H.
Published: December 2007

This regional investigation contributes to the understanding of the influence and relationship of gathering areas and seals to oil habitat in the Arabian Basin. Cross plots and cumulative frequency distribution plots characterize the hydrocarbon habitat and lead to the following inferences. Gathering or fetch area size and contemporaneous peak oil generation rank as important factors in the accumulation of giant Middle East oil reserves. The importance of excellent seals to Middle East oil abundance should be moderated by recognition of widespread peak oil generation to seal effectiveness.

The highest frequency of fields with several stacked reservoirs occurs in areas of modem peak source rock generation. Thin seals can be effective. Gross seal lithology is not as important as previously thought. Vertical migration through seals is an important process. Seals leak but are effective. Cross plots of original oil in place versus field gathering area identify areas of rich/thick source rock or sweet spots. Inefficiencies resulting from long distance migration are not apparent.

Sweetness map analysis, using gathering areas with assigned oil-in-place values, results in an inferred source rock distribution that contrasts with published source rock distributions.
Abqaiq Hajifa Reservoir: Geologic Attributes Controlling Hydrocarbon Production and Water Injection
Authors: Grover G. A.
Published: December 2007

The Hanifa reservoir at Abqaiq Field consists entirely of mud-supported limestones that lack megascopic pore spaces. Porosity in the Hanifa reservoir is in the form of micropore spaces, spaces ≤10 microns in size. Microporosity is evidenced by high porosities (5-32%) within these fine-grained rocks based on porosity logs and coreplug analyses, absence of any visible porosity (even in thin sections) to account for the high pore volumes, and 2000X SEM images that show a crystal framework texture composed of microrhombic (day-size) caldte crystals with 2-5 micron size pore spaces between caldte crystals. The microporosity is considered to reflect retention of primary intercrystalline spaces within the precursor lime mud sediment, and with little introduction of allochthonous caldte to ocdude pore spaces.

Flow meters indicate that the reservoir is capable of produdng/injecting large volumes of oil/water, but with no stratigraphic predictability to the flow, and that thin (2-10 ft) low porosity (<15%) intervals can contribute over 60% of the entire flow. These reservoir attributes, coupled with the low "matrix" permeabilities (0.1-10 md) of the reservoir indicate the presence of an apparent permeability that is controlling fluid flow. Core studies revealed that this apparent permeability is in the form of high angle fractures. The fractures are ≤ 1 mm wide, contain hydrocarbon residue and caldte cement, and many are in dose assodation with high amplitude stylolites, suggesting a genetic link between stylolitization and fracturing. Bore hole imaging log data is providing value insight into fradure location, abundance, orientation, and size in non-cored wells.

The Hanifa is separated from the giant Arab-D reservoir by over 450 feet of fine-grained and impermeable carbonates of the Jubaila Formation. However, these two reservoirs are in pressure-fluid communication via a network of fractures through the Jubaila carbonates. This reservoir communication together with the reservoir heterogeneity of the Hanifa, in the form of micropores and assodated fractures, provides a challenge for reservoir geology and reservoir engineering to formulate a development plan, involving horizontal producers, to mitigate reservoir communication and to effidently and effectively extract the reserves within the Abqaiq Hanifa reservoir.
Implication of Wrench Tectonics on Hydrocarbon Reservoirs, Abu Dhabi, U.A.E.
Authors: Marzouk I. M. , Sattar M. A.
Published: December 2007

Wrenching is one of the main tectonic styles that affected East Arabia during the Geologic history.

Primary and secondary Wrench related structures were identified at several localities in Abu Dhabi.

Shape, orientation and size of several oil and gas fields are mainly controlled by primary Wrench Tectonics.

Secondary Wrench related structures i.e. strike-slip faults, dip-slip faults, associated fracture systems and other deformations have significant impact on hydrocarbon reservoirs in Abu Dhabi.

Examples of these implication are: -Enhanced reservoir quality at predictable trends.-Directional permeability and early water breakthrough.-Hydraulic communication between separate reservoirs and production/injection problems.-Reservoir discontinuity and development problems.

Practical field examples from Abu Dhabi oil and gas fields were discussed.
Reservoir Characterization Integrating Borehole Imagery and Conventional Core Data, Unayzah Fm., Hawtah Field, Central Saudi Arabia
Authors: Heine C. J.
Published: December 2007

The use of borehole imagery along with core data has significantly improved the reservoir mapping within the Hawtah Field. Borehole imagery provides an azimuthal direction to the core based depositional model. Net sand isopach maps contoured using the oriented geologic model provide a quality set of maps suitable for geologic modelling and ultimately reservoir simulation. When core is absent, borehole imagery can be used to help identify the lithofacies present, particularly in fields where several wells have both conventional core and borehole image data. The accurate tying of core porosity and permeability back to logs has always been an educated guess, especially when there is less than 100% core recovery. The recognition of sedimentary structures and textures on borehole images add confidence to the log-core correlation and porosity-permeability adjustments to logs.
Turnkey Drilling in Lekhwair
Authors: Oude Essink W. H. , Wijsbeek H. J. , de Lange J. L.
Published: December 2007

In 1990 PDO awarded the world1! biggest Turnkey Drilling Contract with a scope of work for 112 wells for the development of the Lekhwair field. An option to drill an additional 56 wells was included.

This paper gives an overview of the strategy and objectives that led to the award of this Turnkey Contract.

The Lekhwair Turnkey Contract, which covers a large number of wells, was supported by the preparatory work of a Multi-Discipline task force. The team, consisted of staff from Drilling Engineering, Production Engineering as well as Petroleum Engineering. The main issues addressed by the task force were: to agree on the well designs in relation to the field development concept and to formulate the basic input for the scope of work for a Turnkey type Drilling Contract

The paper discusses the Management principles for Turnkey Drilling Operations whereby the focus is given to Management of the Turnkey Contract, Quality of the Product, Health, Safety and Environment (HSE) issues and the Performance of the Turnkey Contractor.

Finally a summary of learning points, including innovations in the rig design as well as the novel approach to the management of subcontractors in this Turnkey concept are presented.
2D and 3D Well Planning for Horizontal Wells
Authors: Kikuchi Shuichi
Published: December 2007

Horizontal well planning involves so many factors and constraints such as target, kick-off or sidetracking point, build-up rate, reservoir formation dip in horizontal section, etc. Each of them must be considered separately. A specific well course planning is the key to drill horizontal well successfully as well as optimizing the directional tools and procedures. As a result, it leads to improve the drilling efficiency significantly and minimize the overall cost for horizontal drilling. However, the process of using an analytical approach in developing and finalizing the plan is time consuming. Therefore, it is vital to make use of a computer model for faster and easier process. For this purpose, '2D' and one of '3D' models with geological data base have been developed and their integrity has been confirmed by bench mark tests. A unique feature of these models is that they can produce not only a well profile but also supplemental requirements, i.e., the estimation of intersection with a certain single or multi-dip formation, the vertical distance between well course and reservoir formation top in horizontal section and casing setting depths. This paper describes theoretical equations adopted for the in-house computer models and presents the results obtained using planned well data.
Log Determination of Residual Oil Saturation in the Mauddud Zone, Bahrain Field
Authors: Wolff Martin , Al-Jalahma A. M. , Hook P. F.
Published: December 2007

Sixty years of crestal gas injection in the Mauddud zone of the Bahrain field has been instrumental in maintaining reservoir pressures and preventing water encroachment. Oil drainage from the gas cap has been a very successful and efficient means of oil recovery. Determining an accurate residual oil saturation in the gas cap is vital for refining reserves estimates and calculating EOR targets.

Various methods for this determination have been used in the past and are being used now including open-hole log evaluation, capillary pressure data, relative permeability data, and cased-hole log evaluation. This paper presents the first application in this reservoir of new- generation pulsed neutron capture logging tools with sufficient accuracy to allow quantitative determination of oil saturations in the gas cap. Results of a multi-well study are presented including a statistical analysis of measurement and interpretation parameter errors.
An Integrated Approach to Production Log Interpretation
Authors: Catala G.N. , Torre A.J. , Theron B.E.
Published: December 2007

The classical practice in quantitative production log interpretation involves the use of the tandem flow and density measurements. The usual companion logs such as temperature and pressure are traditionally only exploited qualitatively and for the determination of insitu fluid properties.

This paper presents a scheme and its associated algorithms that handles all available measurements. It is flexible enough to accommodate non traditional and upcoming sensors. Such capabilities are needed in light of the complexities associated to multiphase fluid flow in deviated wells.

The method is based in a process which seeks to reconstruct all available measurements. It uses an iterative procedure which at each step assumes the solution, i.e., the individual phase flow rates. The algorithm uses a minimization technique aimed at obtaining a minimum difference between the theoretical sensor responses and the measured log responses. The resulting output is a flow profile versus depth of the individual liquid and gas phases. This method has been successfully applied worldwide and in particular in the Middle East.

To illustrate the capabilities of the method, four Middle East examples are presented in this paper. The first example shows how the temperature sensor can compensate the hampered spinner measurement due to the high deviation of the well. The second one demonstrate the integration of standard production logging sensors in a three-phasic case. The third example shows the use of a non-traditional measurement, Water Flow Log (WFL*), in a three phase flow situation. The last one, also a triphasic case, includes a tracer ejector and a capacitance meter in addition to the standard string.

Introduction

Production logging is intended primarily for measuring the performance of producing and injecting wells. It provides diagnostic information, pinpoints where fluids such as water, oil and gas are entering a well, and gives an indication of the efficiency of perforations.

In vertical wells, where there are relatively high flow rates and one or two fluid phases, traditional production logging analysis produces reliable results. However, if spinner readings are unavailable or suspect, the logging analysis can be severely hampered. In such cases, the fluid flows from various intervals cannot be quantified. This could happen in low-flowing or highly deviated wells.

Figure 1 shows a typical production log where the spinner measurements have been severely affected by three adverse conditions -low flow rate, highly viscous fluid and high deviation.

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Partnering Creates Network for Continuous Improvement
Authors: Prehoda G. D. , Bowman M. D. , Porterfield N. L. , Greenwalt W. R.
Published: December 2007

Drilling/completion procedures and well productivity are always the major concerns in any oil company. The enhancement of these concerns led to the partnering of operator/service company personnel. Partnering, alliances, and integrated services have become effective methods in the nineties for creating the network necessary to implement total quality management in our industry. This paper presents a one-year analysis of the objectives, results, improvement process, and technical advances made through a team effort (major operator/multi-functional service company) utilizing an in-house engineer. To increase value received from the investment was the objective measured by the partnership. Enhanced communication and technology applications compressed the vision which prompted the placement of a service company engineer directly in the operator's office. A complete line of service company computer design and evaluation software and required hardware were installed. The in-house engineer became a full team member within the operator's organization and complete integration of the two companies began on a daily basis.

Primary/remedial cementing, stimulation, gravel pack, and tool design are all services that have been impacted by this partnership. New techniques were jointly developed along with detailed procedures to help the field perform successful treatments. Well-productivity increases were another direct benefit. Productivity-versus-cost ratio was improved as over-expenditures decreased. The handling of multi-service responsibilities became centered under one person. The inhouse engineer concept allowed a quick and accessible response to areas needing immediate attention. The infusion of both companies' technology, methods and creativity generated cost saving ideas, procedures, new equipment designs, as well as stronger emphasis on the evaluation process. Design, execution and evaluation reports were completed on all wells, setting up the criteria to begin the benchmarking of results and the subsequent tracking for improvement comparison on future wells. The paper addresses how each of the processes helped create the network for continuous improvement.
CaO- and/or MgO-Swelling Cements: A Key for Providing a Better Annular Sealing?
Authors: Ghofrani Reza , Plack Heiko
Published: December 2007

The use of expanding cements for improving the sealing efficacy of annulus cementing has been considered for a long time as a possible solution to existing problems. In this paper, the processes of volumetric shrinkage of cements due to hydration as well as the effective mechanisms of CaO and MgO swelling cements are explained. Preliminary results of the current investigations at ITE for testing cement systems of this kind for application in the borehole are presented. The expansion of the cement matrix has been determined with the use of atmospheric and HPHT expansion cells specially developed for this purpose. Further parameters under investigation include the permeability of the system comprising the cement and steel pipe as well as the strength properties.

Formation of voluminous Ca(OH)2 and Mg(OH)2 crystals on the surfaces of the cement particles resulted in matrix expansion by more than 10 percent, even under a hydrostatic pressure of 120 MPa and at borehole temperatures up to 175°C. The swelling cements under investigation exhibited especially high shear bond strength. The test results hitherto obtained already indicate that the sealing action of annulus cementing can be improved with CaO swelling cements when employed preferentially in storage wells with BHST up to 70°C, and with MgO swelling cements in deep gas wells with BHST up to 175 °C.
Solved Problems of High-Density and High-Temperature Drilling Fluid in an Environmentally Sensitive Area
Authors: Cesaroni Renzo , Repetti Umberto
Published: December 2007

A new approach was taken to develop drilling fluid systems which were applied on the Villafortuna/Trecate Oilfield in the Po Valley.

The necessity to provide adequate environmental protection and at the same time facilitate optimum drilling performance is described. Hell conditions require drilling fluids of high density which are stable to high temperatures. At the same time, the drilling sites were located in the environmentally sensitive Ticino River National Park.

Although the usage of oil base fluids in 1983, at the beginning of production drilling operations, would have allowed for satisfactory well conditions throughout the program, it was decided to pursue the usage of water base fluids that would ensure better drilling performance and the minimum of environmental risk, leaving oil base mud only for directional drilling.

The fluid systems that were ultimately used were based upon both field and laboratory experience. The paper outlines the rationale of how this experience was applied and relates field results to the approach taken.

The technology that is discussed in the paper describes the water base fluid that was eventually used, the solids control equipment and the actions taken to operate in accordance with the environmentally protective approach.
Mechanism for Wellbore Stabilization With Lime-Based Muds
Authors: Hale A. H. , Mody F. K.
Published: December 2007

The lime-based mud was one of the earliest drilling fluids developed. It has been utilized not only when drilling CO2-containing formations and other potentially harmful contaminants but also for borehole stability. Data are shown which support a fundamental mechanism whereby lime impacts borehole (in)stability. The data demonstrate specific alterations in rock strength and chemistry as a function of drilling fluid composition. Hot rolling dispersion tests and triaxial compressive tests show that shales, treated with a variety of lime-based combinations, harden with time and temperature. These changes in rock strength occur concurrently with changes in cation exchange capacity, composition, and water reactivity of the shale. These results suggest that changes in rock strength are related to the changes in mineral composition. The data indicate that lime-based systems not only can be formulated to minimize the amount of borehole instability but in fact actively stabilize the hole.
Advanced Influx Analysis Gives More Information Following a Kick
Authors: Billingham John , Thompson Martin , White D. B.
Published: December 2007

We present an efficient, new procedure for characterising a kick by analysing changes in surface pressures, surface mud flow rates and pit level. This procedure allows us to determine, faster and more reliably than is possible with conventional methods: the times when the influx started and stopped, the formation pressure, the influx type (even for a horizontal well), the formation permeability and the maximum casing shoe pressure. The performance of this procedure has been tested using data from both a gas kick simulator and a series of controlled experiments in a 4500 ft test well. We present examples of our results, which show good agreement between predictions and observations. This analysis has been implemented in a rig based monitoring system, [1].