bluuebunny/crossref_metadata_2025 huggingface dataset:
Quality Assurance for Field Mud Testing Equipment
Authors: Geraghty S. , Motley T.
Published: December 2007

The functional properties of drilling fluids are critical to safe and economic drilling operations. It is fundamental that equipment in use to check drilling fluid properties is operating correctly within clearly defined limits and documented accordingly. It is important that any procedure is documented concisely and is sensibly applicable under wellsite conditions.

This paper examines the development criteria, implementation of calibration and function testing procedures of drilling fluid testing equipment used by mud engineers at the wellsite. Set protocols establish standard methods and certificates of analyses establish standard reporting procedures.

Distinction is made between function testing, a quick simple field engineer's check, and calibration for equipment which fails the function test and requires repair. Not only are operational parameters examined but also safety aspects, especially with regard to pressurised equipment.

Although several calibration procedures are known for certain pieces of equipment (rheometers and retorts) these are often impractical for wellsite application. The procedures require special calibration equipment or are onerous to perform and therefore neglected. Many heuristic procedures in use are wrong.

The formalised and documented methodology presented here provides the quality assurance necessary for the work being done. This ensures greater consistency of data and confidence in it. Regularly performed function tests alert the field engineer as to the accuracy of data and quality of measurements.

In conclusion, field engineer response to implementation will be examined with a discussion on the benefits, problems and findings.
The Internal Pressure Capacity of Crescent-Shaped Wear Casing
Authors: Song J. S. , Bowen Jerry , Klementich Frank
Published: December 2007

Drill pipe operations inside casing produces a crescent-shaped wear pattern. Such wear can compromise the design integrity of the casing string. The lack of an adequate method of calculating the rupture pressure of crescent-shaped wear casing prevents an accurate assessment of the true safety factor of the string, as opposed to the strings initial yield pressure design factor. This paper presents an accurate method for calculating the internal rupture pressure of crescentshaped wear casing as verified by experimental results. The true safety of the string can thus be assessed and operations adjusted accordingly.
Development of a Cartridge Data Transmission System for Use with Air Drilling Motor
Authors: Shale Les , Moberley G. T.
Published: December 2007

A cartridge data transmission (CDT) system has been developed for use when drilling with air and gas. The CDT system employs a steering tool that allows orientation of the drilling motor in a particular direction, while still allowing drilling straight ahead with drillstring rotation. The system can be easily converted for fluid drilling where this "poor man's MWD" has real economic and operational advantages.

The CDT system uses a specially ruggedized steering tool which provides continuous surface readout of drift angle and azimuth of the hole, as well as toolface orientation while drilling ahead. A hard wire from the steering tool through the drill pipe and kelly to the surface, relays information to computerized surface equipment. Date transmitted from the steering tool is updated and converted instantly to information which can be used to make any necessary corrections to the motor to ensure the target is reached and the well completed.
Application of Soft-Torque Rotary Table in Mobile Bay
Authors: Javanmardi Kazem , Gaspard D. T.
Published: December 2007

Shell Offshore Inc. (SOI) has successfully installed and operated the Soft Torque Rotary System (STRS) for the first time on two drilling rigs operating in Mobile Bay. Application of the STRS has significantly reduced torque fluctuations (up to 80%), torsional drill string vibrations, and bit slip-stick conditions. The STRS attenuates and interrupts the torsional oscillations of the drill string and thus prevents the buildup of energy in torsional waves that are reflected back and forth between the bit and the rotary table. It can be installed on any rig equipped with an independent electronically driven rotary table or top drive. The STRS is inexpensive (about $25M for Shell group companies), easy to install, and has been a factor in improved drilling penetration rates realized on the SL 531 No. 3, a complex directional well drilled in the Mobile Bay area. Additionally, the STRS has been instrumental in avoiding expensive ($5MM-$10MM) drill string failures on the SL 531 No. 3. Further work needs to be done to fully quantify the impact of the STRS on reducing these types of failures.
Surfactant/Cement Blends Improve Plugging Operations in Oil-Base Muds
Authors: Harder C. , Carpenter R. , Wilson W. , Freeman E. , Payne H.
Published: December 2007

Achieving a competent kick-off plug can be a difficult task, especially when cementing in oil-base mud (OBM). Historically, kick-off operations in OBM have required numerous costly and time consuming attempts to establish a good plug.

Portland or hydraulic cements require water wetting of their chemical components to initiate and maintain the hydration process. If the hydration process is interrupted, so is strength development. OBM impedes cement hydration by oil-wetting the cement components. Laboratory testing indicates as little as 10% by volume OBM mixed with cement can dramatically affect cement thickening time and compressive strength (see Figure 1 and Figure 2).

Cements mixed with water-wetting surfactants have significantly improved plug success rates in an area where plug failures in OBM were commonplace. The water wetting surfactant used in these tests effectively reduced the OBM contamination. Compressive strength, thickening time, and rheological testing have shown surfactant/cement blends to be more tolerant of OBM contamination (see Table 1). In field tests, using surfactant cements, only one attempt was required to establish a competent kick-off plug. In a three well program, a $2000 surfactant expenditure produced a projected $300,000 savings.
Sensitivity of Early Kick Detection Parameters in Full-Scale Gas Kick Experiments With Oil- and Water-Based Drilling Muds
Authors: Anfinsen B. T. , Rommetveit Rolv
Published: December 2007

Gas kicks in oil- and water-based mud have been studied in an inclined research well. One of the main objectives has been the study of early kick detection. Data on pit gain, stand pipe pressure and mud return flow have been systemized in all the kicks in order to evaluate the performance and sensitivity of these parameters. The sensitivity of the detection parameters have also been compared for various kick types. The results show that several surface detection parameters are necessary in order to optimize detection. The reduction in pit gain due to gas solubility in OBM is shown to be significant The mud return flow was the most sensitive parameter in OBM. In WBM also pit gain and stand pipe pressure were valuable for kick detection. New detection signs have been found on the return flow signal in OBM and in kicks with MWD pressure pulsing.
An Evaluation of Flowmeters for the Detection of Kicks and Lost Circulation During Drilling
Authors: Schafer D. M. , Loeppke G. E. , Glowka D. A. , Scott D. D. , Wright E. K.
Published: December 2007

An independent evaluation of current industry standard and state-of-the-art drilling fluid inflow and outflow meters was conducted during the drilling of a geothermal exploratory well. Four different types of fluid inflow meters and three different types of fluid outflow meters were tested and evaluated during actual drilling operations. The tested drilling fluid inflow meters included conventional pump stroke counters, rotary pump speed counters, magnetic flow meters, and a Doppler ultrasonic flow meter. On the return flow line, a standard paddle meter, an acoustic level meter, and a prototype rolling float meter were evaluated to measure drilling fluid outflow rates. The prototype outflow meter utilizes a rolling float which rides on the surface of the flow thereby measuring the fluid height in the pipe. Both die prototype meter and the conventional paddle meter were also extensively tested under a variety of drilling conditions in a full-scale laboratory test facility. The meters were evaluated and compared on the basis of reliability and accuracy, and the results are presented in the paper.
Effectiveness of Conditional Simulation To Describe Carbonate Reservoir Properties
Authors: Perez Godofredo , Kelkar B. G.
Published: December 2007

Conditional simulation is a geos tat is tic al approach to generate multiple equiprobable distributions of a property with specified univariate and spatial attributes. These attributes are derived from sample data or inferred from external infor-mation. This paper evaluates the effectiveness of conditional simulation to describe distributions of porosity in a carbonate environment.

The reservoir studied produces from a dolomitized for-mation of complex lithology. The conditional simulation methods tested are the simulated annealing simulation (SAS) and the sequential indicator simulation (SIS). A validation procedure is introduced to compare observed and simulated porosity distributions and to quantify the quality of two- and three-dimensional conditional simulations. Results of three-dimensional validations indicate that SAS yields a good overall reproduction of observed porosity distributions. Comparisons of equiprobable two-dimensional distributions suggest that the quality of the porosity descriptions for SAS are slightly better than for SIS.

These results show that conditional simulation renders descriptions which capture variations of a property due to inherent geologic complexities. The major advantages of conditional simulation over traditional methods are: (l) it incorporates in a distribution of a property different degrees of variability for different directions, and (2) it accounts for uncertainties in the description.
The Effect of Delayed Enzyme Breakers on Filter Cake Cleaning in Southeastern New Mexico Stimulation Jobs
Authors: Laramay S. B. , Norman L. R. , Carathers B. K.
Published: December 2007

Enzymes are useful breakers in water-based fracturing fluids, but delaying the release of the enzyme provides many advantages. These advantages include delaying the break of the fluid to provide improved fluid rheology, increased breaker concentration improves fracture conductivity and a solid filterable breaker concentrates the added breaker in the fracture. These advantages will lead to better proppant placement and improved production increases.

A study of the interdependence of temperature and pH on enzyme activity was investigated. These results indicated the limitations of enzymes as breakers in fracturing fluids, but the lifetimes of enzymes at higher pH and temperature were longer than expected. Laboratory investigation of improved fluid performance was investigated using delayed static break time, improved viscosity profiles, and filter cake dissolution study. Static break times were significantly longer than normally obtained in typical low temperature fracturing fluids with conventional enzyme breakers. This also resulted in better viscosity profiles especially in early time. Filter cake dissolution studies pointed to the usefulness of the delayed release enzyme breaker in cleaning filter cakes prepared from linear and borate crosslinked gels, but fluids crosslinked with metal ions were not cleaned.

Actual field trials made in a Southeastern New Mexico study wherein the delayed release enzyme breaker was used also point to the effectiveness of the delayed release enzyme breaker in improving fluid performance. Increased initial water production and sustained oil production were the results when the delayed release enzyme breaker was used. Another facet of the protection of the enzyme in high pH fracturing fluid was also examined. The delayed release enzyme breaker was successfully used in a pH 9.5 fracturing fluid.
Perils to the Free World's Essential Oil Supplies
Authors: Levy Walter J.
Published: December 2007

The Free World Depends Increasingly on Foreign Oil

Since the beginning of World War II foreign oil has gained an ever greater importance in the oil supply of the United States and the other nations of the free world. During 1939 this country produced over 3.6 million barrels daily of crude oil and related products permitting, after satisfying domestic requirements, a net export of some 350,000 barrels a day. Beginning with 1948 the United States has been a net importer of oil, and during the first half of 1952, when production, at 6.7 million barrels daily, was over 85 per cent higher than in 1939, the net imports of the United States amounted to some 500,000 barrels daily.

The most recent studies of the future development of the U. S. oil industry indicate that this trend toward an ever growing importance of foreign oil in the U. S. supply pattern will not only continue but is likely to be greatly reinforced. According to estimates of the President's Materials Policy Commission [PMPC], this country, by 1975, will produce 11.2 million barrels daily of crude oil and related fuels, including shale oil and other synthetics. Its requirements will be as much as 13.7 million barrels daily, necessitating net imports of 2.5 million barrels a day. As a result it is likely that the United States, which has in the past obtained the bulk of its imports from the Caribbean area, will in the future absorb not only the total surplus production in the other countries of the Western Hemisphere but will also require large supplemental quantities of crude oil from the enormously rich fields of the Middle East. Similarly the free countries in the Eastern Hemisphere, which procured a large portion of their oil needs before World War II from the United States and the Caribbean, import now over two-thirds of their greatly increased requirements from the Middle East and less than one-quarter from the Western Hemisphere.

This change in the supply position of the United States and free world is based on a fundamental shift in the relative size of proven crude oil reserves in the United States and in foreign oil-producing countries. At the end of 1938 U. S. reserves, at 17.3 billion barrels, constituted 61 per cent of total free world reserves of 28.5 billion barrels. By the beginning of 1952 proven crude reserves in the United States, although they had risen to 27.5 billion barrels, represented only 29 percent of the reserves of the free nations, which had reached a total of 95.5 billion barrels. Foreign reserves, mostly located in the Middle East, had accordingly increased from 11.2 billion to 68 billion barrels. If the most recent estimates for Middle East oil reserves had been used, the latter figure would even be some 20 billion barrels higher.
Automatic Well Testing Using a Two-Phase Separator
Authors: Fransen Gary
Published: December 2007

The traditional methods of testing the production of oil wells have involved the task of separating the produced stream into its components; oil, water, and gas. However, development of an energy absorption device for measurement of oil/water mixtures in any ratio has eliminated the need for three-phase separation. This technology allows the use of a much simpler, less expensive and more accurate system: the two-phase well tester.
Reservoir Management of Light Oil Steamflood Pilot in the SOZ Fault Block, Elk Hills Field
Authors: Hong K. C. , Blunschi J. H. , Cease C. C. , Madison D. L.
Published: December 2007

The light oil steamflood pilot in the SOZ Fault Block at the Elk Hills Field, Kern County, California, has been managed by a team of geologists and engineers. To assist the reservoir management efforts, a history-matched, large-scale reservoir model was developed. A simulation study with this model quantitatively assessed the performance decrease from well productivity damage and the lack of reservoir confinement. It further showed that waterflood would have been the process of choice for recovering oil from this type of reservoir. The study indicated that future recovery strategy should aim at the oil banks that have moved out of the pilot area during steam injection, and should include a means to pressurize the reservoir. This can best be accomplished by converting the pattern steamflood to a line-drive waterflood and drilling additional wells to capture the displaced oil. A recommendation based on these findings is currently being implemented in the field.
New Technique Provides Better Low-Density-Cement Evaluation
Authors: Harness P. E. , Sabins F. L. , Griffith J. E.
Published: December 2007

Ultra-lightweight cements have been used throughout the industry for many years as a specialty cement for application in areas of weak formations. Typical lightweight slurries use hollow ceramic microspheres or nitrogen and other low specific gravity materials to maintain light slurry densities while providing good compressive strength development. The one problem with these systems has been the evaluation of the job via sonic tools. This paper will introduce a new technique to allow an accurate interpretation of a sonic cement evaluation and will be demonstrated from laboratory model studies.

Light cement evaluation studies show a statistical variance technique to be the preferred method of evaluation in its class. Standard methods of cement evaluation rely on the contrast in acoustic properties of materials behind pipe. The Cement Bond Log (CBL) acoustic amplitude is used to derive compressive strength. The ultrasonic tool uses acoustic impedance to derive compressive strength. However, in the process of lightening the cement slurry, the acoustic properties of the cement can approach the acoustic properties of a fluid. Modeled values were compared to measured values of various slurries from 16.4 lb/gal to 9.0 lb/gal, confirming the trend from high acoustic impedance contrast of a cement to a drilling fluid in the case of a 16.4 lb/gal slurry to a negative contrast in the case of a 9.0 lb/gal slurry.

Situations can arrive where drilling mud will be displaced by a cement slurry of the same density. Standard cement evaluation techniques would not be able to identify the cement in this case because of a lack of acoustic impedance contrast. Another technique is available for low-density cement evaluation that identifies the cement from the fluid behind pipe by quantifying the other statistical variance of the acoustic impedance measurement. It will be demonstrated that there is a difference in the impedance measurement statistically between a solid crystalline cement and fluid, even though the absolute values are the same.

Additional work will demonstrate the difference between designed lightweight cement with nitrogen and cement that has been subjected to gas migration.
New Technology Improves the Performance of Borate Fluids in Low-Temperature Zones of the Belridge Field
Authors: Laramay S. B. , Shelley R. F. , Hatcher W. B.
Published: December 2007

In high pH, low temperature fracturing fluids, enzymes are not useful breakers because enzymes are not active in high pH solutions. When these types of fluids are used, oxidizing breakers are used in conjunction with activators to break water-based fracturing fluids. A delayed release oxidizing breaker which it's operable temperature range is between 70 – 125 °F has been developed. This breaker is useful in delaying the break of high pH, low temperature fracturing fluids. Improved fluid rheology in the applicable temperature range was also attainable with this product. Filter cake dissolution studies pointed to the usefulness of the delayed release product in cleaning filter cakes of borate fluids. This product will allow the breaker concentration to be increased over the amount of conventional breaker currently added. This will lead to improved fracture cleanup. Actual field trials made in a Belridge Field study suggested that improved performance of borate fluids in the low temperature zones was attainable. Using a borate fluid with the delayed release breaker added allowed more sand to be placed in the fracture and increased cumulative oil production.
A Study of the Base of Fresh Water in the Southern San Joaquin Basin, California
Authors: O'Bryan P. L.
Published: December 2007

This paper presents a study done to determine the base of fresh water in the southern San Joaquin basin in California. Presented is a base of fresh water contour map for the study area as well as a Rwe versus Rw correlation for determining Rw from the SP which was developed for fresh waters found in the study area.
The Ultrashort Radius Radial System Applied to Thermal Recovery of Heavy Oil
Authors: Dickinson Wade , Dykstra Herman , Nees J. M. , Dickinson Eric
Published: December 2007

Over 1,000 horizontal and curved radiais have been placed in unconsolidated, sandstone and limestone formations in the U.S. and Canada with the Ultrashort Radius Radial System. All radiais are drilled with high pressure, water-based fluids (69 MPa (10,000 psi)) with appropriate additives. These radiais move from the vertical to the horizontal around a 30 cm (1 ft) radius of curvature. Multiple radiais (up to 20 per layer) and multiple layers (up to 5 layers) have been successfully drilled. Most radiais have been positionally surveyed. Horizontal completions including open hole, Flexible Sand Barrier (flexible permeable casing), and gravel packing have been employed. Some radiais have been placed using Control While Drilling which incorporates real-time downhole indication of drillhead trajectory coupled with real-time trajectory control supplied by small thrust jets which move the drillhead up or down so as to follow a desired trajectory.

Field conditions of water coning, natural fracturing, hard-soft inclusions, shale partitions, faulting, and other common reservoir heterogeneities have been encountered. Applications have been made in both heavy and light oils. A typical successful controlled injection/production (huff and puff) application of the system with production results is described in detail.
An Emerging Economic View of World Natural Gas Demand and Supply
Authors: Dorsett W. H. , Ackerman G. B.
Published: December 2007

Natural gas is swiftly moving from a locally traded commodity in regional markets to a globally traded commodity. This paper describes a numerical model of international gas trade which evaluates the effects of inter- and intra-regional gas trade on demand, supply and price.

Preliminary evidence indicates natural gas prices are 15 to 30% lower in real terms when inter-regional trade occurs and local consumption of natural gas increases relative to fuel oil in the local market.

Natural gas developers or marketers that explicitly consider the inter-regional impacts of gas trade will have a greater likelihood of understanding the risks in marginal projects and are more likely to embrace economic projects and eschew non-economic projects.
The Future Gas Market in Europe: Opportunity or Dilemma to the Producer
Authors: Lindberg Per
Published: December 2007

The views of a major North Sea gas producer on the future development of the European markets for natural gas will be presented by Statoil.

The presentation will focus on the anticipated growth of the demand for gas in Europe and discuss the main driving forces, such as environmental concerns, gas demand for power generation, diversity of energy supply and the emerging opportunities in Eastern/Central Europe. Further more the views from a supplier and a gas seller observing the possible, future structural changes of the European gas market now subject to discussion and definition in the European Community will be presented. In conclusion, the consequences for Norway as a gas supplier will be discussed.
New Developments in Petroleum Investment Contracts
Authors: Walde Thomas
Published: December 2007

Since there have been structures of public government, economic interest in minerals and technical ability to extract them, there has been mineral legislation and methods of giving permission to miners - by the owners of the land or the owner of subsurface mineral rights - to extract them. Issues which we now consider important, for example, access to land, payment to the owner/sovereign for extraction of minerals, supervision of mining activities and safety, both for miners and third parties, ancillary economic contribution of mining to local communities - have been around for a very long time. These issues are still relevant and their regulation - in legislation, subsidiary regulations, in mineral agreements and licensing conditions -evolves and responds to advances in technology, to new economic concepts and financing methods, to new political attitudes and constraints.

When viewing current licensing methods negotiatiated petroleum and mineral development agreements - one can therefore both come to the conclusion that nothing is veritably new and that current agreements contain significant innovation.

The present paper does therefore not pretend to claim that there is a revolution with dramatic innovation in current licensing, but rather surveys the -sometimes substantive, sometimes rather more formal - changes in current licensing and negotiating practice.

Current licensing & negotiating has to be viewed before the political and economic background:

The 1970s were the time of strong assertion of state sovereignty, over economic and political emancipation of developing countries resulting in large-scale nationalization, renegotiation, emergence of strong state resource companies supported by foreign loans. Resource endowment was seen as an important lever to gain economic power and private investment was excluded, restricted and constrained, an attitude best illustrated in Decision 24 of the Andean Pact of 1976. This attitude has changed, first gradually and currently, in the aftermath of the collapse of the supposedly ever-rising petroleum price in 1985 and the wake of the collapse of state socialism, with dramatic speed, scope and depth. Encouragement of foreign investment is the order of the day, remnants of the 1970s restrictions are dismantled everywhere, ex-socialist countries are rushing into foreign investment as a panacea for their woes and strongly entrenched state enterprises are being restructured and move towards privatization.
Trends in Production-Sharing Contracts in Nigeria
Authors: Ofoh E. P.
Published: December 2007

Nigeria, as a member of the Oil Producing and Exporting Countries (OPEC), today operates various forms of Joint Venture arrangements. From 1908, when oil exploration first began in Nigeria by a German company, the Nigerian Bitumen Corporation (NBC), through 1937 when Shell D'Arcy took concession of the entire country as a single block to 1972 when more than 13 international companies joined the entrepreneurship, the Nigeria Petroleum Industry has witnessed numerous forms of Production Sharing Contract agreements. These arrangements which reflected state of the art of industry at the time, ranged from simply Tax and Royalty only through "Equity Sharing" to "PRODUCTION SHARING" AGREEMENTS. In addition, each phase of these agreements partly reflected the following:

Prevailing Fiscal and Economic Environment in the Country. National Development and International Obligations/Needs. State of Global Economy.

This Paper will discuss among other things:

– The Economic implications of each arrangement to both Joint Venture partners. – The possible future trends and their implications. – The salient points in each arrangement shall be highlighted.
Non-Commercial Risk and Financing Energy Investments in the Least Developed Countries - The Case of Africa -
Authors: BONO J.
Published: December 2007

Since there have been structures of public government, economic interest in minerals and technical ability to extract them, there has been mineral legislation and methods of giving permission to miners - by the owners of the land or the owner of subsurface mineral rights - to extract them. Issues which we now consider important, for example, access to land, payment to the owner/sovereign for extraction of minerals, supervision of mining activities and safety, both for miners and third parties, ancillary economic contribution of mining to local communities - have been around for a very long time. These issues are still relevant and their regulation - in legislation, subsidiary regulations, in mineral agreements and licensing conditions -evolves and responds to advances in technology, to new economic concepts and financing methods, to new political attitudes and constraints.

When viewing current licensing methods negotiatiated petroleum and mineral development agreements - one can therefore both come to the conclusion that nothing is veritably new and that current agreements contain significant innovation.

The present paper does therefore not pretend to claim that there is a revolution with dramatic innovation in current licensing, but rather surveys the -sometimes substantive, sometimes rather more formal - changes in current licensing and negotiating practice.
Real-Time Expert Systems for Drilling Operations Support
Authors: Corti Martino , Galinetto Rita , Sansone Aldo
Published: December 2007

This paper describes ADIS Real Time Expert Systems (RTES) status and results. An overview is given both on ADIS Project and its Real Time System of which RTES are part

Drilling know-how is used to drive RTES in trasforming raw and bulky sensors data to high level and compact drilling information. This includes operating state determination, time analysis, data validation, trends evaluation and alarm generation. Currently under development are expert systems to support the handling of critical events, namely kicks and pipe stickings.

At the moment RTES are operated as a part of the whole ADIS Real Time System at one rig site and in AGIP main offices. At least one further rig site and one district office will be operating by the second half of 1992.
Properties and Application of Delayed-Release Breakers
Authors: Parker M. A. , Laramay S. B.
Published: December 2007

Water-base fracturing fluids gelled with guar-based polymers are used for fluid loss control, viscosity development, and proppant placement in hydraulic fracturing operations. These polymers must be subsequently degraded with breakers such as enzymes, oxidizing agents, or acid. Prevention of premature reaction of these additives with the fracturing fluid may be accomplished by encapsulation of these breakers, thereby providing a delayed release. Many aspects concerning selection, testing, design, and application of delayed release breakers have been investigated and are presented in this paper.

Laboratory testing has been done, including (1) methods of product preparation and corresponding release profiles, (2) viscosity degradation using delayed release breakers and conventional breakers, and (3) determination of breaker requirements. Fracture conductivity data are also presented to show the benefit of these materials to improve the results of a treatment. Case histories are presented to show results of the application of these materials.
Integral Type Curves for Advanced Decline Curve Analysis
Authors: Spivey J. P. , Gatens J. M. , Semmelbeck M. E. , Lee W. J.
Published: December 2007

This paper introduces a new family of type curves for advanced decline curve analysis. The new type curves are obtained by combining the dimensionless production rate and the dimensionless cumulative production on a single log-log scale. The new type curve offers two significant advantages: 1) observed cumulative production data is much smoother than observed production rate data, making a match easier to obtain with the new type curve; and 2) simultaneously matching both rate and cumulative production provides more confidence in the selection of the correct early- and late-time stems. Plotting functions are presented to allow the new curves to be used for both oil and gas wells produced at either constant or varying flowing bottomhole pressure. Use of the new type curves is demonstrated for both simulated and field data.
New Developments in Nitrogen in the Oil Industry
Authors: Evison Brian , Gilchrist R. E.
Published: December 2007

The generation of nitrogen for Enhanced Oil Recovery has reached a degree of sophistication such that almost any size project can be considered. In the past, one limiting factor has been the availability of small (economic) nitrogen producing plants. The recent development of small nitrogen producing plants utilizing membranes has allowed the use of nitrogen to be considered for many new opportunities.

Membrane produced nitrogen can be used in areas where natural gas is not available. For example, it finds instant application in attic oil reservoirs both on-shore and off-shore, where a "huff-and-puff' procedure is applicable. Nitrogen from membrane systems can be used in coal-bed methane projects. Membrane systems, like cryogenic air separation plants, are now available where a "third-party" owns and operates the system on a supply contract.

Nitrogen gas for the oil industry is now more readily available in a greater size range, and for any time period.
Analysis of Inflow Performance Simulation of Solution-Gas Drive for Horizontal/Slant/Vertical Wells
Authors: Chang Ming-Ming
Published: December 2007

The inflow performance relationship (IPR) developed through numerical simulation of vertical, horizontal, and slant wells in solution-gas drive reservoirs was analyzed. The IPR is essential to optimize production design; however, little information is available for interpreting the change of IPR with wellbore geometry and depletion stages. Gas saturation, PVT properties, and formation pressure close to a wellbore were investigated to interpret the shape of IPR curves at various flowing bottomhole pressures and stages of depletion. The effect of oil gravities on IPR curves was studied, and newly developed IPR curves for slant wells were compared to those for horizontal and vertical wells.

Horizontal well IPR curves fall on both sides of Vogel’s reference IPR curve for a vertical well. Horizontal wells show a better productivity improvement with additional pressure drawdown than vertical wells at the early stage of depletion. Horizontal well IPR curves increase their curvature with depletion up to 8% then slightly decrease in curvature at later stages of oil recovery. This trend, different than that found for vertical wells, is due to a high gas production rate from horizontal wells at low bottomhole pressures before oil recovery reaches 8%. The decrease in curvature of IPR curves for a vertical well with depletion is due to a slightly higher formation pressure around the wellbore at lower flowing bottomhole pressures at later stages of depletion.
Spirit (Minnelusa "A") Unit: A Case Study in Unitization
Authors: King W. A. , Flahive R. M. , Zwart D. W.
Published: December 2007

Many Minnelusa fields in the Powder River Basin have been successfully unitized and water-flooded. However, forming the Spirit (Minnelusa "A") Unit was more complicated than most. This Unit required the lawyers, geophysicists, landmen, and engineers to each solve a piece of the puzzle, which when fit together formed the Unit.

The main producing well in the Spirit field lies outside the boundary of the Lily (Minnelusa "A") Unit. Reservoir production and pressure response indicated it was draining a fairly large area and was not responding to nearby water-floods or supplied by a natural waterdrive. Drilling to the north, east and south failed to find commercial pay. Apparently, the Spirit (Minnelusa "A") field extended west into the Lily (Minnelusa "A") Unit. However, it was producing from a Minnelusa "A" accumulation which was not in hydraulic communication with the Lily reservoir.

This paper describes how the ownership problem was resolved, the field was defined, the injection and production responses forecasted and how the water-flood actually has responded to date.
Estimation of Effective Permeabilities for Reservoirs Initially Above Bubblepoint Pressure
Authors: Hatzignatiou D. G.
Published: December 2007

This work investigates the effects of initial reservoir pressure on the computation of effective permeabilities for homogeneous and heterogeneous solution-gas-drive reservoirs which are initially above the bubble-point pressure. The heterogeneous system considered is that of a two-zone composite reservoir with different absolute permeability and/or relative permeability curves in the two regions. It is shown that the initial effective oil permeability may be estimated from drawdown and buildup pressure data. It is also shown that one can obtain accurate estimates of computed effective permeabilities as pointwise functions of wellbore pressure from drawdown data during the time period that the wellbore pressure is less than the initial bubble-point pressure. From the estimates of effective permeabilities obtained, it is shown that for the case of homogeneous solution-gas-drive systems one can construct approximate effective (or relative) permeability curves by nonlinear regression analysis techniques. For the case of heterogeneous solution-gas-drive reservoirs it is shown that if the initial reservoir pressure is above the reservoir bubble-point pressure then the effective oil permeability of the inner or the outer zone might be obtained from the analysis of drawdown and/or buildup pressure data.
Pressure Transient Analysis for a Three-Region Composite Reservoir
Authors: Ambastha A. K. , Ramey H. J.
Published: December 2007

Usually, well tests from enhanced oil recovery projects, such as steam injection, in-situ combustion, and CO2 flooding projects, are analyzed using a radial, two-region composite reservoir model. However, a three-region model may be more appropriate in many cases. An analytical solution for the transient pressure response of a well in a radial, three-region reservoir is available. But a detailed study of the transient pressure and/or pressure derivative response of a well in a three-region reservoir has not been presented in the literature.

Using an analytical solution, this study establishes the ratio of the intermediate region radius to the inner region radius as a correlating parameter for the transient pressure derivative responses for a three-region reservoir. Additional four parameters are related to the mobilities and the storativities of different regions. This study shows that the deviation time method would result in an estimate for the inner region radius, if the effects of the mobilities and the storativities of the inner and the intermediate regions are not balanced in a way to produce an incorrect deviation time.

Analytical expressions for the effective porosity-compressibility product and mobility are developed for the analysis of pressure transient data by the pseudosteady state (PSS) method. The PSS method would result in an estimate of the combined volume of the inner and the intermediate regions, if an effective porosity-compressibility value is used to analyze the pseudosteady data. However, at times, the development of an apparent pseudosteady state may yield an overestimated volume. An idea about the development of an apparent pseudosteady state may be obtained by calculating the effective dimensionless time corresponding to the time to start of an approximately constant Cartesian slope for the pressure transient data in question.
Formation Heating and Oil Recovery by Steam Injection into Linear Porous Media
Authors: Avendano Horacio , Magnani Charles F. , Farouq S.M.
Published: December 2007

Discussion of this paper is invited. Three copies of any discussion should be sent to the Society of Petroleum Engineers Office. Such discussions may be presented at the above meeting and, with the paper, may be considered for publication in one of the two SPE magazines.

Mathematical models were developed for predicting the extent of the heated zone in predicting the extent of the heated zone in steam injection into a linear porous medium, having a circular or rectangular cross-section, surrounded by an infinite, heat-conducting medium. The models were used to predict the steam zone advance in typical oil reservoirs. Results were compared with those obtained when using models for uniform thickness formations. The heat loss behavior for the two types of models was also compared.

The mathematical models were further employed to predict the growth of the heated zone in a typical laboratory system, in particular a core which consisted of an uninsulated particular a core which consisted of an uninsulated steel pipe, filled with glass beads, the surrounding air serving as the infinite heat-conducting medium. Good agreement was obtained between the predicted and the experimental results.

The mathematical models were extended for prediction of oil recovery from laboratory cores, prediction of oil recovery from laboratory cores, using continuous steam injection. Examples of such predictions are given and compared with experimental data.

The proposed mathematical models provide an important means of correlating laboratory data, and make it possible to obtain useful information from experiments. Moreover, in a number of field situations the models may provide better predictions of formation heating provide better predictions of formation heating than the existing models.

Introduction

Injection of a hot fluid into a porous medium results in the formation of a heated zone, which, at any given time, is related in a complex manner to the instantaneous rate of heat injection, heat losses up to the time of interest, and the heat utilized for heating the porous medium and the fluids contained in it. porous medium and the fluids contained in it. Marx and Langenheim presented a theoretical treatment of this type for steam injection into a formation of infinite areal extent, and uniform thickness, with infinitely thick formations overlying and underlying it. Ramey extended this treatment for a variable injection rate.

The present work considers the injection of steam into linear porous media, having circular or rectangular cross-sections, situated in infinite heat-conducting media. The calculated steam and hot water front positions can be employed for computing oil recovery using the method proposed by Willman et al.
Reservoir Modeling Through Integrated Processing Between Seismic and Well Log Data (Thamama Reservoirs in Offshore Abu Dhabi)
Authors: Belaid K.H. , Lafet Yves
Published: December 2007

_

Nowadays, the seismic reflection is playing an increasingly significant rolein the development of oil fields in addition to the detection of hydrocarbontraps of even greater stratigraphic and structural complexity.

This paper presents and describes an integrated method using seismic and well data to predict, quantity and map the porosity variations within four reservoirs in the Thamama Group in two structures named "A" and"B" and located offshore Abu Dhabi.

The seismic and well data were processed and aimed to produce a Noise free sections presenting a high Signal-to-Noise ratio. The data were processed in a True-Amplitude and a Zero-Phase sections were produced providing a good matching with the well data. These Zero-Phase sections were inverted to an Absolute Acoustic Impedance sections which were calibrated with the impedance logs generated at the wells.

The different factors that may affect the porosity in the four studied reservoirs were investigated and a relationship between the porosity and the acoustic impedance was established.

This relationship along with the calibrated absolute impedance sections were used to produce porosity maps for the Thamama reservoirs.

After the completion of this study, two wells were drilled in this area and the results are in general satisfactory. The comparison between the predicted and real petrophysical reservoir parameters can be summarised as follows:

Depth : error about 0.7% H (thickness x porosity): The average error for all the studied reservoirs in the two wells is about 10%.

Introduction and Objectives

This study was carried out by the Compagnie Generale De Geophysique (CGG) in 1987/1988 with the contribution and under the Supervision of ADMA-OPCO.

The area of the study is located offshore Abu Dhabi, as indicated in Figure-1.

This study covered two structures "A" and "B".

The first exploration well drilled on the Structure "A" was in 1981and it was a discovery. The oil-bearing reservoirs occur in the Thamama Group Lower Cretaceous age. The first well in the nearby Structure "B" was drilled in 1989 and discovered oil in the Thamama zones I, II and IV.

The main objective of this study was to evaluate the potentialities of the different reservoirs in the Thamama Group.
Drilling Contractor Dilemma for the Nineties: Performance and Service With Profit
Authors: Irwin J. R.
Published: December 2007

During the 1980s, offshore drilling contractors learned the harsh lessons of survival. That meant reducing costs, conserving cash, avoiding debt, maintaining market positions and retaining key people. The survival mode permitted neither profitability nor growth. Certain contractors did not survive, and drilling industry consolidation is still underway; rig supply/demand equilibrium is not expected to be reached in the near future. The business, which has historically been cyclical, is now undergoing further fundamental changes and long-term restructuring in a number of ways: clients’ methods of doing business; areas of geographic focus and rig distribution; number and location of contracting companies; and the modified character of client companies.

While offshore drilling contractors must retain the flexibility to meet the differing and changing needs of various clients, one of the significant changes sought by some operators is a broader range of services which can be offered by contractors. Changing business relationships are still in transition in 1992 as contractors continue to build technical and commercial experience, and operators gain confidence in contractors’ ability to perform safely, efficiently and economically. An important factor in establishing trust and mutual respect is a keener understanding by both parties of the other's investment criteria and costs, including the future implications of rig ownership. The future role of "alliances" and "partnering" between operators and contractors, and preferred supplier relationships for contractors with a serious long-term commitment to the business are also becoming more important to address.

Contractors and service companies do not share directly in the ultimate reward of a successful discovery or producing well, but reputable contractors can - and want to - make professional contributions to operators’ drilling projects. The dilemma for the serious long-term offshore drilling contractor in this decade is how to survive in a condition to furnish the level and range of services that will better satisfy operator requirements, provide safe, total quality performance - and still find a way to earn an acceptable profit as a service company and asset owner in a capital intensive business. The question remains even for financially healthy contractors and service companies: "How do we survive and become profitable over the longer-term?"