bluuebunny/crossref_metadata_2025 huggingface dataset:
Acoustic Measurements on Cores as a Tool for Calibration and Quantitative Interpretation of Sonic Logs
Authors: Marion Dominique P. , Pellerin François M.
Published: December 2007

An upscaling technique is developed for acoustic measurements on cores to present core data as a log for improved comparison between laboratory and sonic measurements. The method combines a laboratory study performed over a wide range of frequency, pressure, and saturation conditions on a series of core samples and construction of a synthetic log that includes upscaling of core measurements at the sonic wavelength and simulation of the log response for various spacing of the tool receivers. A comparison of core and sonic measurements in a carbonate reservoir illustrates the benefit of comparing core and log measurements at the same scale. Agreement between punctual core and sonic measurements is within ± 10%, whereas core data upscaled at the level of sonic measurements are within ± 2% of the sonic. In addition, results of quantitative interpretation of the sonic data in terms of porosity also confirm that sonic measurements can provide accurate estimates of petrophysical properties when properly calibrated with core data.
Legal Problems in Undersea Mineral Development
Authors: Ely Northcutt
Published: December 2007

As the depth of water in which we can drill increases, the problem of jurisdiction grows more and more complex. What was once the magic number200 meters - has become meaningless. The question is, how do the coastal nations arrive at a fair definition of rights in exploiting the undersea mineral resources of the earth?

Introduction

The subject we shall consider here concerns two questions:To what seaward boundary should the U. S. assert, consistently with this country's international commitments, exclusive American jurisdiction over submarine mineral development?Beyond the limits of national jurisdiction, what international arrangements to govern mineral development are in the best interests of the U. S., and, pending the negotiation of such arrangements, what law governs? In considering these questions we must be aware of other national interests-national defense, navigation, fisheries, protection against pollution, to name some of them.

A nation's jurisdiction can be likened to a bundle of sticks. Landward of a base line, which is the low-water line or straight line joining points along an irregular coastline, the coastal nation has exactly the power that it has on land, a complete bundle of power that it has on land, a complete bundle of jurisdictional sticks. Outward from the base line to the limit of territorial waters, say 3 miles, as our Government insists, or 6 or 12 or more, as other nations claim (there being no formal international agreement on this), the coastal nation has most of the sovereign powers that it has on land. These extend to all four powers that it has on land. These extend to all four elements of the marine environment - the sea bed, the overlying water column, the water surface, and the superjacent air space. This near-plenary control over territorial waters is subject, under international law, to an easement in favor of innocent passage of merchant ships, and warships in peacetime, subject to certain restrictions. Beyond territorial waters, some sticks begin to fall out of the bundle of sovereign powers. Coastal nations, under international law, have some powers beyond the belt of the territorial sea, but these are restricted, extra-territorial powers.* The Convention on the Territorial Sea and the Contiguous Zone provides (Art. 24) that a contiguous zone may be provides (Art. 24) that a contiguous zone may be established to encompass a belt 12 miles wide measured from the same base line from which the territorial sea is measured. In this contiguous zone, the coastal nation may, for example, exercise limited controls to prevent infringement of its customs, fiscal, prevent infringement of its customs, fiscal, immigration, or sanitary regulations "within its territory or the territorial sea". Beyond that, the surface of the ocean is part of the high seas over which the coastal nation has no more power than does any other nation of the world. The freedoms of the high seas include those of navigation, fishing, the laying of submarine cables and pipelines, and of overflight by aircraft.

JPT

P. 237
Snap-Off of Oil Droplets in Water-Wet Pores
Authors: Roof J.G.
Published: December 2007

When oil emerges from a water-wet constriction into a water-filled pore, the interfacial forces are such that a leading portion of the oil may separate into a droplet (snap off). Theory indicates that for a given shape of constriction, there is a minimum size to the protruding portion of the oil that permits snap-off. If the oil/solid contact angle is zero and if the constriction has the shape of the throat of a tore (a doughnut hole), the oil must protrude for a distance of at least seven times the throat radius before snap-off can occur. Experiments were performed in approximately toric constrictions constructed of glass. Liquids used were a dyed mineral oil and a water-ethanol mixture adjusted to the same density as the mineral oil to avoid gravitational effects. Within the limitations imposed by visual distortions through the glass and the liquids, the observations appear to be in accord with the theoretical predictions.

Introduction

Production of oil from a reservoir involves flow of oil through a porous medium that also contains water. Because of the small size of the pores in the reservoir rock or sand capillary forces at the oil-water interface are of considerable importance in determining the nature of the flow through the pores. This report deals with one aspect of such pores. This report deals with one aspect of such How, determining the conditions that must be met in order that the oil emerging from a water-wet constriction will separate (snap off or pinch off) into a droplet in the larger parts of the channel. By applying the fundamental equation of capillarity to oil flowing through certain geometrically describable water-wet constrictions we can calculate the minimum size of the protruding body of oil that will permit snap-off of the oil to give a separate droplet. The theoretical treatment can be checked, at least semiquantitatively, by observations on dyed mineral oil flowing through glass pores previously filled with a water-alcohol mixture. This mixture should be adjusted to give be same density as that of the mineral oil in order to eliminate gravitational effects, which can be large relative to capillary effects in constrictions having an internal diameter of about 2 mm.
Case Study of a Horizontal Well in a Layered Rotliegendes Gas Field
Authors: Catterall S. J. A , Yaliz Ayk
Published: December 2007

A horizontal well was drilled in the Ravenspum North field to drain a thin gas column above the aquifer. The field has a significant variation in reservoir quality, with most of the wells requiring stimulation by hydraulic fracturing. The reservoir is formed from a stacked sequence of aeolian dune and fluvial sandstones with a wide permeability range. The horizontal well was chosen as an alternative to stimulation by hydraulic fracturing to avoid water production from the aquifer. The well was successful, flowing at higher gas rates than expected with no water production. Production, core, and production logging data were used to demonstrate greater than expected lateral heterogeneity in the field. The horizontal well was found to be appropriate for the very specific conditions found in one part of the reservoir; however, the overall development strategy of using hydraulic fracture remains the preferred technique.
Construction and Validation of a Numerical Model of a Reservoir Consisting of Meandering Channels
Authors: van Vark W. , Paardekam A. H. M. , Brlnt J. F. , van Lieshout J. B. , George P. M.
Published: December 2007

This paper discusses the modeling of a fluvial reservoir system. Construction of a detailed reservoir model was followed by a coarser numerical simulation model. During the history matching of the latter, we found that fluid transmissibilities had to be reduced significantly to reproduce the observed pressure differentials. Fault-related features are thought to be the reason that the sand continuity is so much lower than that predicted with sedimentological considerations only.
Development Planning in a Complex Reservoir: Magnus Field UKCS Lower Kimmeridge Clay Formation
Authors: Leonard A. J. , Duncan A. E. , Johnson D. A. , Murray R. B.
Published: December 2007

This paper addresses the problem of how the static geologic description of a complex, low net/gross reservoir can be combined with dynamic production data into full-field reservoir simulation for use in development planning. The discussion focuses on an integrated petroleum engineering study of the LKCF of the Magnus field in the U.K. sector of the North Sea.
The Offshore - An Engineering Challenge
Authors: Russell D.G.
Published: December 2007

An Interview with D.G. Russell

Offshore petroleum exploration and production on a worldwide basis continuesto expand at an extraordinary rate. Current worldwide production is about 6.5million B/D. The domestic scene, dampened somewhat by the Santa Barbara blowoutand the proposed new operating guidelines, shows signs of a quick return torecord activity. This special Offshore Issue of JPT includes six technicalarticles dealing with many phases of offshore operations. The paper by Lewis G. Weeks, beginning on Page 377, provides an overview of the current offshorepicture. The special JPT feature on the First Annual Offshore TechnologyConference begins on Page 429. SPE and AIME have played a major role indeveloping the Conference, which is cosponsored by nine of the world's leadingtechnical and scientific organizations. Included in the feature is the completetechnical program, with abstracts of some of the papers to be presented. TheSPE program was developed by the sub-committee headed by E. E. Sands, Jr., withUnion Oil Co. of California in Houston. Also included is a complete listing, beginning on Page 441, of the more than 330 technical exhibits that will be ondisplay at the Conference. A certain "mystery" still overshadows theoffshore. Questions such as "How can oil companies pay these high pricesfor offshore leases?" and "Where are the best undeveloped offshoreprospects?" are topics of considerable conversation. To secure an expert'sappraisal of these and other issues, JPT asked D. G. Russell, ProductionManager for the Southeastern Region of Shell Oil Co., to provide readers withhis views. Don is well known to JPT readers for his numerous publications, butis perhaps best known as coauthor of the Society's first monograph, PressureBuildup and Flow Tests in Wells.

Q. What do you think the short (9 months to a year) and long range effectsof the Santa Barbara crisis will be?

A. The over-all effects of the Santa Barbara crisis are difficult to assessat the present time. Certainly there are some short range effects alreadyapparent; for example, the suspension of operations in the Santa Barbarachannel and the postponement of Gulf of Mexico lease sales pending issuance ofnew drilling regulations. As to long range effects, the industry will simplyhave to wait to assess these until the Department of the Interior doespromulgate new drilling and production regulations for the offshoreenvironment.

Q. In your opinion, how do how do most oil company managements view offshoreresources today --- from art economical standpoint? from a technologicalstandpoint?

P. 369
Sand Transport and Deposition in Horizontal Multiphase Trunklines of Subsea Satellite Developments
Authors: Oudeman Pieter
Published: December 2007

Gravel packing is unattractive as a way to protect against the effects of sand production in subsea wells because it involves additional completion costs, loss of productivity, and difficulties in subsequent recompletion/well servicing operations. On the other hand, omitting gravel packs means that subsea developments must be designed and operated so that they can tolerate sand production. An experimental study was carried out on sand transport and deposition in multiphase flow in modeled subsea flowlines to address the problem of sand collection in horizontal trunklines, which could lead to reduced line throughput, pigging problems, enhanced pipe-bottom erosion, or even blockage. This study led to the definition of a new model for sand transport in multiphase flow, which was used to establish the risk of sand deposition in trunklines connecting a subsea development to a nearby production platform.
A Study of Diversion Mechanisms by Reactive Water Diverting Agents
Authors: Thompson Karsten E. , Fogler H. Scott
Published: December 2007

High water saturations in producing zones of petroleum formations cause problems during both acidizing and production. Water diverting agents are designed to prevent some of these problems by selectively plugging watered-out strata. Reactive water diverting agents are oil-based fluids that provide selective plugging because they react with aqueous formation fluids to form permeability reducing gels. This study used laboratory formulated diverting agents to elucidate the plugging mechanisms that result from in-situ interfacial reactions and gel placement. Our results show the physical characteristics of the media and gels necessary to bring about effective plugging and also the conditions that typically prevent selectivity. Additionally, a simple treatment method called the injection/back-flow procedure is introduced, which helps achieve a highly selective diversion treatment.
Parallel Linear Solvers for Reservoir Simulation: A Generic Approach for Existing and Emerging Computer Architectures
Authors: Bhogeswara Rao , Killough J. E.
Published: December 2007

Recent architectural advances in the computer industry focus on the numerical solution of intensive flows, such as in oil reservoirs, on several processors simultaneously. Different computer architectures evolved from connection of these processors: shared memory with a few processors, distributed memory with up to a few hundred processors, and massively parallel with several thousand processors. Oil industry researchers are developing efficient techniques to improve hydrocarbon recovery in reservoirs by use of these computers. In this work, a generic approach is developed to solve the large system of sparse linear equations that arises in reservoir simulation. This approach uses a combination of domain decomposition and multigrid techniques that results in efficient and robust algorithms for sequential computers with one processor and for parallel computers with few to several tens of processors. The efficiency and robustness of these methods is comparable with widely used sequential solvers for problems of practical interest, which include implicit wells and faults. In parallel, these methods prove to be an order of magnitude faster on a 32-node iPSC/860 hypercube.
Hybrid-CVFE Method for Flexible-Grid Reservoir Simulation
Authors: Fung Larry S.-K. , Buchanan Lloyd , Sharma Ravi
Published: December 2007

The flexible control-volume finite-element (CVFE) method is used to construct hybrid grids. The method involves use of a local cylindrical or elliptical grid to represent near-well flow accurately while honoring complex reservoir boundaries. The grid transition is smooth without any special discretization approximation, which eliminates the grid transition problem experienced with Cartesian local grid refinement and hybrid Cartesian gridding techniques.
Computer-Aided Real-Time Kick Analysis and Control
Authors: Jardine S. I. , White D. B. , Billingham John
Published: December 2007

After early kick detection, the most important activities during well-control operations are correct identification of shut-in pressures, preparation of the kill plan, and careful monitoring of the kill operation. This paper describes the development and application of tech-niques to analyze and to extract the maximum amount of information from surface pressure measurements during shut-in.
Well Kill (Quenching) Study of Thermal Producers in the South Belridge Field, California
Authors: Fram J. W.
Published: December 2007

This paper presents a field study confirming that damage occurs during kill (quenching) operations of thermal producers in the South Belridge field, Kern County, CA. Implementation of the recommendations from this study are expected to decrease damage that occurs during quenching by an average of 0.5 BOPD/kill. Results indicate that producers completed with openhole, gravel-packed, slotted liners in high-permeability sandstones can sustain substantial, irreversible damage when subjected to unfiltered produced-water kills. The damage results when previously produced sand and fines, which have settled in the flowline, are reinjected into the wellbore. Most of the damage is in the slots and gravel pack. Previous studies, field tests, and laboratory work quantifying the amount and site of the damage are detailed. Methods of determining water-quality specifications needed to minimize damage that occurs during well kills are outlined. The approach presented can be used to identify and quantify damage in any field where producers require kills before workover operations. The current recommended kill procedure is also included.
Acquisition Pitfalls: Operating Cost Forecasts
Authors: Doering M.A.
Published: December 2007

Evaluations of potential oil and gas property acquisitions often prove to be substantially optimistic as a result of errors in operating-cost forecasts. This paper sets forth several potential pitfalls associated with forecasting operating costs that should be considered before an acquisition is consummated. Potential problems are identified and discussed from three general areas:seller-furnished information,field operations and government regulations, andforecasting methodologies.

Introduction

Acquisition of existing producing properties has become an important part of the growth strategies of many oil and gas companies. Many variables must be analyzed and projected to evaluate a potential acquisition, the most significant of which are production rates, product prices, and operating expenses. Each of these variables is critical to the determination of actual property value.

Extensive publications and training courses are available on production-rate projection, and numerous reservoir engineers and geologists specialize in the science of projecting production rates. Past performance history, which forms the basis of most production-rate forecasts, can be verified by checking public records or from copies of revenue checks obtained from the seller. Well tests also can be performed to verify the current producing characteristics of a well. Product-price forecasts also are given extensive attention by both engineers and financial marketing experts. Each company formulates its own product-price forecast (or range of forecasts) applicable during evaluation.

Even with the most accurate production-rate and product-price forecast, however, an oil and gas property acquisition can fail to generate projected profits as a result of errors in the operating-cost forecast. This area of evaluation often is given only cursory attention by the evaluation team and consists of merely mathematically averaging seller-furnished historical costs for the past 6 to 24 months. This analysis method can lead to significant mistakes in property evaluation. We determined several common pitfalls associated with operating-cost forecasts through review of data furnished by potential sellers of more than 800 property packages during the past 6 years and detailed analysis of actual post-acquisition performance of 18 selected purchases. Consideration of these pitfalls will help evaluators prepare more accurate forecasts and reduce the risks associated with this often-neglected area of evaluation.
Reduction of Gas and Water Permeabilities Using Gels
Authors: Seright R. S.
Published: December 2007

We investigated how different types of gels reduce permeability to water and gases in porous rock. Five types of gels were studied, including (1) a "weak" resorcinol-formaldehyde gel, (2) a "strong" resorcinol-formaldehyde gel, (3) a Cr(III)-xanthan gel, (4) a Cr(III)-acetate-HPAM gel, and (5) a colloidal-silica gel. For all gels, extensive coreflood experiments were performed to assess the permeability-reduction characteristics and the stability to repeated water-alternating-gas (WAG) cycles. Studies were performed at pressures up to 1,500 psi using either nitrogen or carbon dioxide as the compressed gas. We developed a coreflood apparatus with an inline high-pressure spectrophotometer that allowed tracer studies to be performed without depressurizing the core. We noted several analogies between the results reported here and those observed during a parallel study of the effects of gel on oil and water permeabilities.
Experimental Study of Nonlinear Effects in Hydraulic Fracture Propagation
Authors: de Pater C. J. , Weijers Leen , Savic Miloš , Wolf K. H. A. A. , van den Hoek P. J. , Barr D. T.
Published: December 2007

We conducted fracture propagation experiments on blocks of cement paste, cement paste with sand, and a tight outcrop sandstone rock. A novel acoustic monitoring system was developed for measuring the fracture profile and radius during the tests.

Results of laboratory tests on cement agreed with numerical simulations based on elastic rock deformation and linear elastic fracture mechanics. Tests at confining stresses of 20 and 23 MPa gave higher pressures than predicted.
Dauphin Island Natural Gas Project
Authors: Layfield R.P. , Elser K.L. , Ostler R.H.
Published: December 2007

Arco Oil and Gas Co. installed the Dauphin Island production facility in a fragile Alabama marine environment supporting important fisheries and tourist facilities. We used proactive communication with governmental agencies, area industry, and the public; innovative construction technologies; and unique platform design to minimize the environmental and aesthetic impacts and to develop an economically successful gas field. The innovative equipment used in the offshore pipeline installation is a model approach for solving certain turbidity problems. The project has received numerous environmental awards.

Introduction

The Mobile Bay area of Alabama is a popular recreational region, containing many sport and commercial fisheries. In 1969, the first oil and gas leases were acquired in Mobile Bay. Within 1 year, applications for the proposed drilling activities were submitted to the U.S. Army Corps of Engineers for approval. The first permit was approved 9 years later. The first well, drilled in 1978, led to the discovery of the Mary Ann field. Production of the deep, sour Norphlet gas was brought on line in 1988, 19 years after the original leases were purchased.

Also in 1988, Arco purchased its first leases in the Mississippi Sound just west of the Mary Ann field (see Fig. 1). That purchase was the beginning of the Dauphin Island Natural Gas Project. After successfully drilling three wells in 1990 and identifying the commercial potential, Arco wanted to secure prompt approval of its development plans. The project resulted in the development of shallow Miocene gas in two fields (North and Northwest Dauphin Island) located about 2,000 ft below the Mississippi Sound.

Concerns About the Development

The economic viability of the project hinged on obtaining timely permits to construct an offshore platform within sight of Dauphin Island and a 15-mile pipeline to transport the produced gas from the platform to its onshore sales point through a different pipe line corridor than used for previous Mobile Bay developments. Some regulatory representatives indicated that all offshore oil and gas developments in the area may be re quired to use an existing, single pipeline corridor several miles east of the development to minimize disruption to wetlands. Also, numerous regulatory and public concerns were stressed during other companies' construction activities that had heightened sensitivity to further developments. The greatest issues were the significant silt disturbances (potentially affecting oyster beds) and possible harm to onshore wetlands during pipe line construction. In addition, concern for area archaeological resources existed because of recent damage during similar types of pipeline construction by other companies. Finally, Alabama regulations required zero discharge in state waters during platform operations and all construction activities.
Modeling of Reservoir Compaction and Surface Subsidence at South Belridge
Authors: Hansen K. S. , Prats Michael , Chan C. K.
Published: December 2007

Finite-element models of depletion-induced reservoir compaction and surface subsidence have been calibrated with observed subsidence, locations of surface fissures, and regions of subsurface casing damage at South Belridge and used predictively for the evaluation of alternative reservoir-development plans. Pressure maintenance through diatomite waterflooding appears to be a beneficial means of minimizing additional subsidence and Assuring as well as reducing axial-compressive-type casing damage.
Multidisciplinary Approach for Targeting New Wells
Authors: Shirzadi S.G. , Lawal A.S.
Published: December 2007

Under currently known reservoir drive mechanisms, initial exploitation of a new field usually leads to drilling in several regions of the field for optimum production. As the field matures, it often is necessary to drill new wells to recover oil reserves trapped because of undetermined reservoir heterogeneity and not acknowledged during initial field development. Targeting new wells in a mature field is challenging because it calls for consensus among interdisciplinary groups (reservoir and production engineers, geoscientists, and drilling and facility engineers). The challenges usually involve estimating the cost and production of the new wells and finding convincing arguments that the existing wells will not drain the trapped reserves adequately. This paper provides a team approach to confront these challenges to target new wells in the mature Prudhoe Bay field. The field example shows that additional oil recovery was obtained with infill drilling.

Introduction

The large, unrecovered mobile oil resource base in the Prudhoe Bay field provides an immediate objective for additional recovery. A significant amount of oil was bypassed at the initial stage of field development because of a lack of knowledge of geologic information and reservoir heterogeneity (defined as the product of depositional and diagenetic processes and structural complexities). Therefore, as part of field depletion planning and to mitigate field decline, infill drilling of new wells often is proposed to increase recovery. In a large field, such as Prudhoe Bay, drilling new wells calls for interaction among professionals in several disciplines: reservoir, facility, environmental, production and drilling engineers, geoscientists, and petrophysicists. In addition, the field is divided into two operating areas. Therefore, cooperation with the partners also is required.

As in other infill-drilling projects, the development plan for drilling new wells in the Prudhoe Bay field was addressed with a multidisciplinary team approach. Also, as in other optimization strategies reported in the literature, the team approach focused on targeting new wells to optimize the depletion plan.
The Integrated Work Team Approach to Performing Reservoir Simulation Studies
Authors: Hazlett W. G. , Johnson R. S. , Sibley M. J. , Thompson J. C. , Bent J. V. , Hrkel E. J. , Bazzari J. A.
Published: December 2007

Modern computer systems help the "integrated work team approach" to be applied effectively in major reservoir studies. Current computer hardware and software facilitate this approach and have allowed superior results to be obtained in a field study of a large Middle Eastern reservoir [3 billion bbl original oil in place (OOIP)]. This paper focuses on the use of computers in each stage of the study. The benefits of being able to update geophysical, geological, and reservoir models easily (as new knowledge is obtained) also is illustrated. For comparison, we present the old reservoir history match developed with a "linear approach" and without the use of current technology.
An Integrated Data Model for Reservoir Simulation
Authors: Aydelotte S. Robert
Published: December 2007

This paper describes the capability of the Epicentre data model to manage reservoir-simulation information, including the spatial model used to describe the properties of the earth and the product-flow network model used to describe production performance. In addition to data values, the data model describes data creation and quality and provides a reliable means of understanding the source. To use the data model, reservoir-simulation applications need to be rewritten to conform to the data-model nomenclature and conventions. While this is a significant task, the benefit to reservoir-simulation practitioners and vendors includes integration of technical applications (such as mapping, well logging, and geophysical-interpretation systems), data portability (allowing Vendor A's simulator to use data prepared by Vendor B's preprocessor), and interoperability (such as using a third-party optimization package to conduct a series of simulations).
A Comparison of Probabilistic and Deterministic Reserve Estimates: A Case Study
Authors: Hefner J. M. , Thompson R. S.
Published: December 2007

Twelve practicing petroleum engineers participated in a study comparing deterministic with probabilistic reserve estimates. Production data for five wells were provided sequentially in four phases covering the first 5 years of production history. A deterministic and probabilistic reserve estimate was made by each evaluator for each phase.

The deterministic reserve estimates were based on Securities & Exchange Commission (SEC) definitions. For the probabilistic reserve estimates, the evaluators were asked to supply three values: P90, P50, and P10. P90 is the value where there is a 90% probability that the actual reserves are greater than this value; P50 is the value where there is a 50% probability that the actual reserves are greater than this value; and P10 is the value where there is a 10% probability that the actual reserves are greater than this value. Most evaluators used their deterministic estimate as the basis for the probabilistic estimates. In these cases, subjective estimates were made rather than using a statistical approach.

The evaluators have more difficulty in estimating the P90 value when the decline exponent b is low. The evaluators have the same difficulty in estimating the P10 value when the decline exponent b is high. In comparing the individual evaluators, there is considerable variability in deterministic, P90, P50, and P10 values. The most variability is in the P10 values. Also, it was observed that over time, as more production history is recorded, P90 values do not approach truth from the low side.
A Rationale for Reservoir Management Economics
Authors: Hickman T.S.
Published: December 2007

Significant economic benefits can be derived from the application of reservoir management. The key elements in economical reservoir management are the efficient use of available resources and optimization of reservoir exploitation through a multidisciplined approach. This paper describes various aspects of and approaches to reservoir management and provides case histories that support the findings.

Introduction

The genesis of this article was my participation in an SPE-sponsored reservoir management seminar in 1992. The invitation to speak on the economics of reservoir management arose from my experience in evaluating reservoir exploitation projects. However, after some reflection, I began to have doubts concerning what the economic considerations unique to reservoir management were. Reserve evaluations are not handled differently just because reservoir management is involved. Likewise, economic hurdle rates are unique to the particular company and have nothing to do with the study process. In a previous seminar, methods of financing projects were discussed. This was interesting but not normally the direct concern of those involved in reservoir management. What then are the unique economic aspects of reservoir management, if any? The answer seemed to lie within the reservoir management process itself.

What is reservoir management? Haven't reservoir engineers been doing this for years? Why all the hype about something that's not a new technology, not even a new concept? Most literature on reservoir management is centered around exploitation of large reservoirs in frontier areas of the world. Does reservoir management have a meaningful role in small reservoirs or mature producing basins? The leading advocates of reservoir management are usually experts in numeric simulation. Is reservoir modeling the essence of reservoir management? Only as these issues about the nature and use of reservoir management were examined did a rationale for the economic aspects develop.

What Is Reservoir Management?

Perhaps this question has been best answered in the negative. Reservoir management is neither a new technology nor the latest management consultant buzzword to justify corporate reorganization. While philosophical aspects to reservoir management exist, it is not an attempt to introduce Japanese management philosophy into petroleum engineering (e.g., total quality management).

Reservoir management has been described as (1) repackaging existing technology, (2) managing advanced technology, (3) long-range/strategic planning, (4) team approach to problem solving, and (5) common sense. All of these contain an element of truth.
Standoff and Caliper Measurements While Drilling Using a New Formation-Evaluation Tool With Three Ultrasonic Transducers
Authors: Moake G. L. , Birchak J. R. , Matthews R. G. , Schultz W. E.
Published: December 2007

A new formation-evaluation LWD tool that employs three ultrasonic transducers to determine tool standoff and borehole diameter is presented. The ultrasonic data are used to improve density and neutron-porosity measurements obtained from the same tool. The paper describes the ultrasonic transducer hardware and operating characteristics, as well as a unique technique for setting the ultrasonic threshold. Data processing procedures and caliper equations are also presented. Downhole phenomena that adversely affect the measurements are discussed, along with solutions used to handle them. Log examples illustrate the effectiveness of the ultrasonic measurements and include evidence of sticking, lateral bouncing, and whirling of the toolstring while drilling. Although monitoring of these undesirable bit motions is not currently available, future tools will be able to communicate this information to the surface to aid drillers.
Field Application of Hydraulic Impedance Testing for Fracture Measurement
Authors: Paige R. W. , Murray L. R. , Roberts J. D. M.
Published: December 2007

Hydraulic impedance testing (HIT) is a technique for detecting and measuring formation fractures intersecting wellbores. A pressure pulse is introduced into a well, and the resulting pressure trace is interpreted to give fracture dimensions. The first part of this paper describes how HIT can be used to estimate fracture dimensions and presents some results from a laboratory experiment that show that dimensions can be measured accurately with HIT. The remainder of the paper describes field examples of the application of HIT. A demonstration of how HIT traces change as pressure is reduced, which provides a method for determining fracture closure pressure, is included.
Pressure Transient Analysis of Fracture Calibration Tests
Authors: Mayerhofer M.J. , Ehlig-Economides C.A. , Economides M.J.
Published: December 2007

Fracture-calibration pressure decline has been used for determination of the leakoff coefficient, a bulk variable describing the process of fluid influx into the reservoir, normal to the created fracture face. In this work, the fluid loss is modeled in terms of the controlling mechanisms: flow through the filter cake, the invaded zone, and the reservoir. A rigorous model describes unsteady-state fluid flow from fractures of varying area into the formation, with the filter cake considered as a time- and rate-dependent skin effect. The injection history is superposed on the pressure decline. This work provides a straight-line technique for determination of reservoir permeability and fracture-face resistance. Log-log diagnostic plots provide the means to recognize visually whether the transient response is dominated by flow in the reservoir or at the fracture face. We found that the pressure transient very frequently is dominated by the flow in the reservoir rather than through the filter cake. The reservoir permeability (an essential value for fracture design that is usually not available) can be estimated, while the model captures all trends of the falloff-pressure variation.

Introduction

The fracture-calibration treatment, also called an injection test or "minifracture," frequently is conducted before the main stimulation treatment. For the injection test, the fracturing fluid intended for the main treatment is pumped at a constant rate of a sufficient magnitude to achieve fracturing pressure. After several minutes (usually 20 to 30) the pumps are shut off and the bottomhole pressure declines as the fracture closes.

During pumping, while the fracture volume grows, some of the fracturing fluid leaks off into the formation. After pumping ends, the fluid leakoff into the formation continues until the fracture is closed. Material balance, coupled with a model of propagation, permits estimation of the rate of fluid loss during pumping.

The behavior of the pressure decline after the end of pumping has been used to estimate the leakoff (fluid-loss) coefficient, with techniques pioneered by Nolte. Castillo, using Nolte's G-function for modeling the pressure-decline behavior, developed the straight-line plot of the G-function vs. pressure. The slope of this curve is used for the computation of the leakoff coefficient that is independent of pressure.
Low-Cost Alternative for Remedial Sand Control Application
Authors: Peavy M. A. , Bush M. E. , Plummer M. A. , Perez J. I.
Published: December 2007

During mid-1992, a remedial workover program was implemented offshore within the Gulf of Mexico on low-rate marginal-reserve sand-producing wellbores. A process called through-tubing gravel packing (TTGP) was used on five offshore wells and one U.S. gulf coast land well. This technique involved the placement of ceramic beads and prepacked screen within existing completions with coiled tubing (CT) to eliminate sand production (Fig. 1). The basic steps of TTGP consist of wellbore cleanup, CT counter correlation, injectivity testing, running a dummy assembly, ceramic bead placement, prepacked screen placement, and installation of an isolation device. The TTGP method demonstrated versatility in adapting to individual well conditions. This remedial sand control technique was successfully applied in highly deviated wellbores, in the upper zones of a dual completion, and within existing gravel packs for screen repair.

TTGP's were performed offshore in as little as 5 days with a CT unit at a cost of $63,500. Five wells were mechanically successful, but only three wells were considered economic successes. Simple individual payouts for the wells ranged from 46 to 77 days, with an associated production gain of 2,020 Mcf/D and 39 BOPD. Economic success improved over time as mechanical success increased. Project incremental production was 1,070 Mcf/D and 38 BOPD. The total cost of the project was $571,807. The average offshore workover cost was $ 110,761, and the workover cost for the onshore well was $18,000.

Throughout the implementation of this program, mechanical problems were addressed that led to improvements in subsequent workover programs. This paper details the TTGP program and recommends mechanical improvements for performing future through-tubing gravel packs.
Criteria for Sizing Multiphase Flowlines for Erosive/Corrosive Service
Authors: Svedeman S. J. , Arnold K. E.
Published: December 2007

API RP 14E provides no specific guidelines for the design of multiphase pipelines for corrosive and erosive service. This paper presents criteria for determining appropriate pipe sizes for clean service and for service where corrosive fluids or solids production are present.
Development of a Matrix-Acidizing Stimulation Treatment Evaluation and Recording System
Authors: Montgomery C. T. , Jan Y.-M. , Niemeyer B. L.
Published: December 2007

When compared with hydraulic fracturing, matrix stimulation has a very high failure rate. This paper describes the development and field testing of a matrix-stimulation field-monitoring system designed to provide real-time control, optimization, and postjob evaluation of matrix treatments. Using calculated bottomhole pressures (BHP) or coil-tubing/tubing-annulus reflected pressures, the system predicts pretreatment damage or skin from a step-rate test, then shows the evolution of skin removal vs. treating fluid volume or time. The system-provides real-time information to the operator conducting the treatment about when to drop diverter, treating fluid efficiency, and diverter efficiency. The system can also be used to estimate treatment height and damage radius. Input data can come directly from the service company's digital sensors or from separate sensors placed in the treating line. A description of the system and several case histories showing its utility are presented.
A New Method for Direct Measurement of In-Situ Stress Directions and Formation Rock Properties
Authors: Lin Peng , Ray Tommy G.
Published: December 2007

This paper presents a new method to determine in-situ stress directions and in-situ formation rock properties with a newly developed downhole extensometer. The extensometer is used to measure wellbore deformation, pressure, and temperature during a microfracture stress test. This paper presents the method used to analyze the data this new device collects. Some of the parameters that can be determined are (1) principal stress directions, determined from the induced fracture orientation; (2) minimum in-situ stress magnitude, determined from the fracture width calculations and the conventional microfracture analysis; and (3) in-situ static rock properties, determined from the prefracture wellbore deformation. This paper emphasizes the theoretical methodology used in the data analysis. A field case example is included.

Introduction

Many production problems-including drilling and wellbore stability, fracturing (for vertical, deviated, or horizontal wells), sand production, and casing failure-require knowledge of the in-situ stress magnitudes and directions, and such in-situ rock properties as Young's modulus, shear modulus, and Poisson's ratio.

Present ways of determining the fracture/in-situ stress orientation at great depths involve either testing of recovered oriented cores [e.g., an elastic strain relaxation, (ASR)] or microfracture tests during drilling and subsequent recovery of the oriented fractured core. A widely accepted method of determining closure pressure (minimum in-situ stress) is microfracture analysis. This type of analysis relies on the pressure-decline data to match a particular model.

Several techniques, static and dynamic, exist for determining rock properties. Static methods usually involve laboratory tests that require carefully prepared samples and often are time-consuming. In addition, retrieved samples are no longer in the in-situ state, and the samples usually are very small compared with the formation being studied. On the other hand, dynamic methods, such as sonic logs, are based essentially on rapidly applied, nondestructive loads. They usually are performed under in-situ conditions. However, statically determined parameters are preferred in hydraulic fracture design because they represent actual loading conditions better.
New Polymer Technology for Water Control in Gas Wells
Authors: Dovan H. T. , Hutchins R. D.
Published: December 2007

A new polymer treatment process has been developed for selectively reducing water permeability in gas wells. Three field treatments are discussed. The most notable treatment was performed on an offshore gas well that previously was loaded up with water. The treatment returned gas production to the well, averaging 1.9 MMcf/D gas for almost 3 years. The water production was reduced from a high of almost 600 to < 50 B/D. The treatment was performed in 1 day using common oil- and gas-field acidizing equipment. The treatment design was based on information from earlier field treatments, laboratory corefloods, and gel screening data.
Incident Investigation and Analysis for Exploration and Production Operations
Authors: Waterfall K.W. , Milne D.J.
Published: December 2007

Incident investigation and analysis in Shell E&P operations is part of performance monitoring in health, safety, and environment (HSE) management systems. The focus is on identifying underlying causes. A step-wise approach is given from immediate response through determining the level of investigation, coverage of investigation aspects, analysis, recording, and follow-up. The means to analyze incidents by application of the Tripod system, which is directed toward understanding underlying causes of incidents, are reviewed.

Introduction

HSE performance monitoring has been, and in some areas still is, based on reactive statistical indicators that can identify at best only that past decisions have resulted in unsatisfactory conditions or work climates. To understand how to improve HSE performance and which managerial aspects have to be changed, it is essential to have a meaningful system for assessing the underlying causes of incidents. The system needs to address not only accidents, where there is a measurable impact resulting from failures, but also situations where no adverse consequences occurred but the potential for loss or damage existed. To make a lasting effect on incident reduction requires a timely, balanced, and consistent approach to "blame-free" investigation of all incidents, identification of underlying factors, and correction of systemic causes.

This paper addresses incident investigation and analysis as part of a structured approach to performance monitoring in HSE management systems. Incident investigation forms an essential part of the feedback loop in an ISO 9000 application to company management and is consistent with recent guidance issued by the U.K. Health & Safety Executive. In addition, we discuss the need to develop and use proactive monitoring systems and indicators.

In 1993, Shell IntI. Petroleum Mij. produced a revised guidance document for Shell E&P operating companies. This paper addresses the changing approach to incident investigation in the E&P industry. The terms "accident" and "incident" have specific definitions in the context of this paper (see the Appendix).
Using a Physical Wellbore Model To Study Formation Damage Problems in Well Completions
Authors: Burnett D. B.
Published: December 2007

This paper describes the design and operation of a high pressure, high temperature wellbore model using either consolidated or unconsolidated core material. It can be configured with up to eight perforated cores representing varied zonal permeability. The model is set up for flow in either the injection or the production direction. It is acid rated and fluids can be pumped at rates to 130 BPD. Gravel-packing is accomplished in the model with either water or polymer carrier fluids.

The model is used to perform laboratory evaluations of completion practices and stimulation techniques. We have evaluated the formation damaging potential of commonly used loss circulation materials and the inability to clean up some of these materials in unconsolidated formations. We have used the model to demonstrate the benefits of gravel pre-packing to avoid loss in perforation flow capacity. We have also evaluated diverting agents designed to improve coverage and stimulation of damaged zones.