bluuebunny/crossref_metadata_2025 huggingface dataset:
Investment Selection Under Uncertainty For Producing Operations
Authors: Sellers David H.A.
Published: December 2007

Publication Rights Reserved

This paper is to be presented at the Eastern Regional Meeting to be held in Pittsburgh, Pa., on Nov. 5–6, 1964, and is considered the property of the Society of Petroleum Engineers. Permission to publish is hereby restricted to an abstract of not more than 300 words, with no illustrations, unless the paper is specifically released to the press by the Editor of the JOURNAL OF PETROLEUM TECHNOLOGY or the Executive Secretary. Such abstract should contain conspicuous acknowledgment of where and by whom the paper is presented. Publication elsewhere after publication in JOURNAL OF PETROLEUM TECHNOLOGY or SOCIETY OF PETROLEUM ENGINEERS JOURNAL is granted on request, providing proper credit is given that publication and the original presentation of the paper.

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

One of the notable features of the modern oil industry is the constant pressure for increased efficiency to meet the challenge of growing costs and increased competition. With increasingly large capital outlays for producing operations, it has become critical that investment be made as effective as possible. For this reason, considerable attention has been given to techniques for insuring maximum benefits from dollar expenditures. It is to our industry's credit that many quantitative methods for dealing with the myriad of assumptions and variable factors of producing operations have received wide acceptance.

One of the most serious and challenging decisions facing a producing company executive is that of selecting from the investment opportunities available the combination which will provide the highest returns. Since budget funds are usually limited, this selection must be made on the basis of economic and operational merit. The degree of merit can be determined only from the information available to the executive and from his experience.

The treatment of risk in capital budgeting Is critical since its measurement is largely subjective in evaluation assumptions and managers' preference for it is variable. Procedures for considering risk range from the simple discounting of expected values of investment returns, to the more complex determination of the utility of the investment. The main disadvantages in existing procedures are the suppression of information and the computational complexity. In brief, uncertainty is a fact of life in producing. We must live with it, and make financial plans accordingly. In dealing with risk, it is the results that should be considered. We must rule out unnecessary risks, but still aim for the high returns.

THE INVESTMENT OPPORTUNITY

Let us restrict the investment opportunities facing a company to producing operations.
Gas Condensate Evaluation in Multi-Layered Systems by Production Logging Tools
Authors: Sarabian A. B.
Published: December 2007

Generally speaking, Gas Condensate Reservoirs may refer to those reservoirs that are producing fluid with the oil gravity of higher than 45°API and the gas-oil ratios of between 5,000 to 100,000 scf/bbl. These types of reservoirs are often found in the deep wells (below 10,000 ft), and the gas that condenses to liquid at the surface temperature and pressure is light color or colorless. Sometimes gas-condensate is called wet gas; the term "wet" does not necessarily mean that gas contains water, it refers to heavier hydrocarbons in the gas mixture.

Table 1. shows the comparison of gas-condesate compositions with the dry gas compositions; as it is seen in this table, the percentage of heptanesplus in gas-condensate fluid is greater than it is in dry gas fluid. This results in higher gas-oil ratio for dry gas fluid at the surface.

In order to understand the behavior of Gas-Condensate Reservoir, the PT phase diagram is presented in Figure 1.
Application of Log-Inject-Log in Granny's Creek Oil Field
Authors: Ahmad Mian Munir , Ovies Sharon Loraine
Published: December 2007

The purpose of this study was to apply principles of the Log-Inject-Log technique through utilization of the Thermal Neutron Decay Time Log (TDT) to ascertain reservoir parameters necessary for an evaluation of a perspective secondary/tertiary flood. This technique provides insitu measurements for determination of residual oil saturation and estimates of bulk volume movable oil and gas saturation. To achieve this purpose log-inject-log was employed in conjunction with open hole log data in a heterogeneous, pressure depleted Big Injun sandstone reservoir. This study represents the first application of the log-inject-log method in the Appalachian Basin.

The log-inject-log process required multiple TDT logging runs following alternate injections of low and high salinity waters. Well site procedures for acquisition of the necessary raw data are presented with a description of the interpretation model. A computer analysis of the data used open hole log measurements as a data base for reservoir characteristics needed to obtain residual oil saturation from the log-inject-log data.
The Effect of Anisotropy and Vertical Fracture Penetration on Production Decline Curves for Low Permeability Gas Wells
Authors: Smith Richard K. , Sawyer Walter K. , Esposito Patrick R.
Published: December 2007

In most reservoir engineering studies, the vertical fracture height and the formation height are assumed to be equal, which may or may not be true. This study investigates the effect of vertical fracture penetration and horizontal anisotropy in the development of production decline curves for a low permeability gas reservoir.

This study shows that the productivity for a given vertical fracture decreases as the fracture position departs from the center of the formation interval. Horizontal anisotropy significantly impacts production decline curves. Up to approximately 70 percent of cumulative recovery is affected significantly regardless of the fracture penetration ratio.
Physicochemical Mechanics of the Propagation of the Stabilized Oil Bank Formed During Dilute Surfactant Flooding
Authors: King Gregory R. , Ertekin Turgay , Stahl C. Drew , Jones J. H. , Nagarajan R. , Yarzumbeck A. J.
Published: December 2007

Recent displacement tests have indicated that under certain conditions the stabilized oil bank formed during dilute surfactant flooding may be composed of as many as three distinct oil banks. These secondary oil banks are characterized by the arrival of high oil cuts, high sulfonate concentrations, and low interfacial tensions in the effluent stream. The mechanisms governing the formation of these three banks, although different for each bank, are related to the interactions between the oil, rock, surfactant solution, and mobility buffer.

To determine the mechanisms governing the formation of these banks, a series of core floods was designed to isolate and study each bank separately. The experimental results, including the production histories and effluent analysis of these tests are presented and discussed.

The results of these tests indicate that two of the banks are formed by the chromatographic separation of high and low equivalent weight sulfonates, while the third is formed by the desorption of sulfonate during the injection of low saline fluids (mobility buffers). Also discussed are the means to alter the production profiles of displacement tests by manipulation of these mechanisms.
Technical and Economic Potential of Enhanced Oil Recovery in Appalachia
Authors: Kuuskraa V. A. , Hammershaimb E. C. , Morra Frank , Wicks Donald
Published: December 2007

This paper examines the future conventional and enhanced oil recovery potential of the Appalachian Basin. It concludes that the cost of finding and producing a new barrel of reserves through exploration is $36. Further, even at prices up to $60 per barrel, conventional oil reserve additions from the Appalachian Basin are only projected at 500 to 700 million barrels.

The other main prospect for increasing recovery is to apply enhanced recovery methods to the 16 billion barrels of oil remaining in-place after primary and secondary recovery. Appalachia's shallow reservoirs, with relatively low pressure, porosity, and permeability, tend to have relatively high residual oil saturation at conclusion of primary and secondary recovery operation. Many of the same reservoirs properties, however, present engineering and economic problems that have limited the region's enhanced oil recovery applications to date. By examining the potential of eight reservoirs from the four largest oil producing Appalachian states, the paper concludes that the three EOR methods most amenable are carbon dioxide, surfactant flooding, and steam drive.
Reservoir and Production Characteristics of Composite Coal/Sandstone Gas Reservoirs
Authors: Rieke H. H. , Galliers F.
Published: December 2007

Exploration for deep Atoka gas reservoirs during the past 10 years in the Arkoma basin of Oklahoma has provided opportunities to obtain reservoir and production data from shallow. Pennsylvanian age, Hartshorne composite coal/sandstone gas reservoirs. The Hartshorne formation by itself is not normally considered to be a potential secondary target if gas shows are evident and the deeper zone is non-productive. Independent operators, however, have been completing shallow wells (<2000 feet) in the Hartshorne formation for over sixty-five years.

Four hydraulically stimulated wells, each having eight years of Hartshorne production history, were chosen to be analyzed. All four of the gas wells are situated on the northern flank of the Kiowa syncline, Pittsburg County, Oklahoma and are located within three miles of each other. The range in depth for the producing Hartshorne intervals in these wells is from about 3000 feet to 4200 feet.

Geophysical well logs, seismic data, sample cutting and core descriptions, gas composition data, well test information and production decline curve analyses were used to characterize the reservoir geology and to estimate the reserves and recovery of these composite reservoirs.

Reserve estimates ranged from .04 BCF to 0.5 BCF per well. Well data suggests that in-fill drilling between these four wells has the potential of recovering more gas. Analysis of the reservoir geology indicates a deltaic-fluvial depositional environment that has several lateral discontinuities in the gaseous Hartshorne coalbed. The geologic data shows that the coalbed can split into as many as three identifiable seams in some parts of the syncline.
Application of Nitrogen Fracturing in the Ohio Shale
Authors: Abel James C.
Published: December 2007

When pumped at sufficient rates and pressures, gaseous nitrogen alone has been successfully used as a fracturing fluid in the Ohio Shale Formation of the Devonian shale trend. Enhanced production results have proved that use of nitrogen, even without a propping agent, has outperformed other stimulation systems employed in this lithological area of Ohio and West Virginia. Job design and procedures for nitrogen fracturing are presented in this paper as are production results of five treatments performed in the Ohio Shale Formation.
Special Purpose Components of Drilling Fluids, the Relevance of Laboratory Tests to Their Actual Use
Authors: Ford D. H.
Published: December 2007

Certain laboratory test work on mud products can be accepted as being relevant to, and correlating with, the conditions met with in actual use. Firstly I want to look at three examples where this is true.

The first example concerns two methods now used for comparing the performance of lubricants in drilling fluids, the Falex test and the core test. The original method used by the industry involved testers producing a metal to metal scar with the dimensions of the scar being taken as a pointer to lubricant performance. In the field the downhole torque is generated by loading between two surfaces and, for the steel upon steel situation, i.e. rotating pipe in casing, the Falex tester gives very good simulation. Figures 1 and 2 show the Falex tester and its mode of operation. The pin is rotated at constant speed and the torque required to do this is measured as the jaw loading on the pin is altered. Figure 3 shows typical results of jaw load and torque when three different products are compared with each other and the base mud. Figure 4 gives the same results in graphical form. From this evidence a judgement as to the likely relative performance of these products in the field can be made with comparative confidence.

Nevertheless even here there can be a real danger of oversimplifying the procedures in order to find a single measurement for evaluation purposes. Time spent at each loading level is important and can significantly alter results, as different products have very different 'skin' durabilities under sustained load. Temperature is also very important and checks need to be made to confirm that alteration for these parameters does not materially alter the conclusions for the case in question. The load at break down is the one usually reported but the load at transition pressure is often more applicable as this is the point of incipient seizure as marked by the acceleration of torque increase. Figure 4 gives a good example of this.
Directional Surveying Using Inertial Techniques - Field Experience in the Northern North Sea
Authors: van Nispen Johan , Howe N A
Published: December 2007

Two FINDS Tools, operated by Eastman Whipstock on behalf of Ferranti Eastman Survey have been on contract to Shell UK Exploration and Production and have completed 63 surveys in a two year period. They have maintained their accuracy specifications with a high reliability which combine to give measurable economic benefits.

Comparisons of results from conventional magnetic single shots, MWD surveys and gyroscopic multiple shot surveys demonstrate that large errors can go unrecognised. The 'Systematic Error Model' of Wolff and De Wardt for instruments of this type is shown to have substantial validity.
Computer Assisted Operations in the Northern North Sea
Authors: Buyzen J. P. M.
Published: December 2007

The paper presents an overview of Shell Expro's Northern Operations and the introduction of a Computer Assisted Operations (C.A.O.) system with the aim to coordinate and manage the offshore production platforms, the pipelines, and the onshore processing plants as an integrated production system.
New Technology in Underwater Inspection
Authors: Gardner W. E. , Wheeler W. J.
Published: December 2007

The importance of a high standard of inspection and maintenance of offshore structures is evident from considerations of safety of personnel, prevention of loss of production due to shutdowns, or pollution of the sea due to oil discharges. These factors are highlighted by the occasional disaster, involving loss of life or the significant release of oil.

Governments and certifying authorities have the responsibility for issuing and enforcing guidelines and regulations for inspection, but these obviously have to be based upon what is technically possible and, in many cases, the technology just does not exist to ensure the desired inspection standard.

The commercial market for inspection in the North Sea alone is expected to grow to approaching £100 million by the mid-1980's, with a figure at least three times as high for the total world market.
Infil Drilling In Old Fields
Authors: Mangunkusumo Rashid I
Published: December 2007

For the past several years P.T. STANVAC INDONESIA has been actively engaged in an infill drilling program in its old fields onshore Sumatra. The primary purpose of this program is to identify and recover remaining accumulations of oil which can not or will not be drained by existing wells.

This paper reviews the results of such infill drilling in Stanvac Is Raja and Abab fields in South Sumatra. The program has already provided a sizeable increase in oil production and reserves in both fields while extending the productive limits well beyond what had been considered to be the field limit.

The program has shown that original field development drilling on 80-acre spacing did not define all of the hydrocarbon bearing zones nor establish ail of the drainage points required to efficiently recover the moveable hydrocarbons in the stratigraphically complex Talang Akar formation. Improved economics resulting from higher energy prices has provided the incentive required to pursue the development of these incremental reserves.
Offshore LNG Production And Storage Systems
Authors: Barden James K.
Published: December 2007

A barge, outfitted with gas liquifaction processing equipment and LNG storage tanks, is suggested as a possible way to exploit remote offshore gas production. A similar study with a barge-mounted methanol plant was done several years ago, also using remote offshore feed gas.

This barge-mounted, LNG system, is bow moored to a single point mooring through which feed gas is piped via seafloor pipeline from a nearby gas production facility. The barge is arranged with personnel accommodation forward, LNG storage midships, and gas liquifaction processing equipment aft. A flare boom is cantilevered off the barge's stem.

The basis of design stipulates feed gas properties, area environmental data, gas liquifaction process, LNG storage tank type plus other parameters desirable in a floating process plant. The latter were concerned with safety, low maintenance characteristics, and the fact that the process barge would also serve as an offshore port where LNG export tankers would periodically moor.

The liquifaction process facilities are described, then the product storage and loading facilities. Relief and flare, hot oil circulation, plant and instrument air, inert gas systems, etc. are described under "other process facilities." The barge itself, ballast, lifesaving and safety systems, quarters and shops, plus the single point mooring are outlined in the next section.

A brief summary of results for a barge-mounted methanol plant from an earlier study is then followed by a comparison of LNG and methanol alternatives. The LNG option appears more favourable than the methanol option.
The Geothermal Potential of Indonesia
Authors: Seal K E
Published: December 2007

An upsurge of interest in the indigenous geothermal potential of Indonesia has followed the Governments encouragement to develop other energy resources as alternatives to oil for the generation of electricity. Accordingly fresh estimates for the geothermal potential of known prospects is proposed.

Only the major fields in Java, Bali, Sulawesi and Sumatra, and which are expected to be developed rapidly, are considered. A brief description of each field is included in the paper and the basis on which the estimates are made is given. Using a modification of the concept, estimation and terminology used in defining mineral reserves, these estimates are quantified. Other factors, expected to influence either way the actual rate of development, are included.

The geothermal potential that is conservatively estimated can be developed in the next 10 ∙ 15 years, is predicted as totalling 1500 MW (e) for the whole of Indonesia. Of this some 900 MW (e) te confined to Java which has the main demand for power.

As well as these major fields, numerous other good prospects are known. Together they may increase the ultimate potential of Indonesia many times what is here suggested. As they are thought unlikely to be rapidly exploited they are not included in these estimates which have been kept deliberately conservative.

A method by which these and future prospects can be ranked in priority is suggested. Based on crude statistical probabilities, the method allows for the combination of factors, other than geothermal, to be taken into account. The resultant quantitative combination, which gives an overall and relative priority, can be of assistance in future planning.
Geothermal Field Development System
Authors: Hirakawa Seiichi
Published: December 2007

The present situation of the geothermal energy developments in Japan is such that six geothermal power stations are being operated and one under construction. Although there are still many geothermal areas to be explored, it will take a long time to realize them. For such a geothermal field development, it is expected to develop a simulation model which can give rational data for planning strategies. With a view to it, the model should be able to simulate physical phenomena in the geothermal field. The system shown in this paper is composed mainly of two principal physical models; Reservoir Model and Well Model. The former is based on the mathematical description of fluid flow through porous media and the latter through vertical pipes. The final purpose of this study is to develop simulation models for optimizing the scheme of geothermal field development.
Drilling Unconsolidated Surface Alluvium with a Downhole Mud Motor
Authors: Pyle Delbert E. , Bush John D.
Published: December 2007

Drilling the 26 in. surface hole in the Tiwi Geothermal Field in the Philippines is characterized by low penetration rates and rough drilling due to the presence of hard andesite boulders in the unconsolidated surface alluvium. This paper describes how drilling time and problems associated with rough drilling were reduced by using a downhole mud motor to power a stabilized 26 in. drilling assembly.
Exploration Trends in Southeast Asia — An Overview
Authors: Fletcher G. L.
Published: December 2007

Exploration in the Far East Region has a very healthy glow at the moment. Significant petroleum related investments are being made in nearly every part of the region. We are even seeing hitherto aloof Governments such as those of Burma, Bangladesh, North Korea, etc. investigate the benefits of foreign investment to spur development of energy resources.

Major investments are being made by Asean countries such as Japan in other Asean countries in order to spur more rapid development of resources and to, intum, secure a supply of energy within the region.

Petroleum related investments are being channeled into two areas, exploration for new hydrocarbon reserves and development or enhancement of existing reserves. The latter emphasis is a relativel new phenomenon which has taken the form of "assistance contracts" in Bangladesh, Burma, Indonesia and recently India. Apparaently the price of oil is such that these projects are, in certain economic circumstances, preferable to straight exploration projects.

As far as geologic trends throughout the region are concerned we are in the midst of an exploration boom in the better known, petroliferous basins. However more and more necomers are arriving on the scene. These entities are pushing back the preconceived frontiers in their competition for exploration acreage. The trend is towards more diverse exploration in lesser known basins and areas. Certainly this also means probing of deeper, older parts of the section in many areas.

Subcontinents such as India with approximately 25 land rigs compared to nearly 4000 in the United States or China with only 300, give one a sense of "room to play". Many explorationist are looking in Southeast Asia with that view. Exploration in Southeast Asia is on the upswing. Geologic and geophysical data is being acquired at an unpresidented rate. All these data indicates strongly that the region is a viable area in which to invest in the search for hydrocarbons.
Drag Reducer Increases Oil Pipeline Flow Rates
Authors: Wahl H A , Beaty W R , Hass G R
Published: December 2007

The use of a polymeric drag reducer to increase the flow capacity of crude oil pipelines is described in this paper. The first commercial drag reducer application began in July 1979, in the Trans Alaska Pipeline. By 1980, flow through the TAPS line had increased to the 1.5 million bbl/D (9,940 m3/h) level. Approximately 200,000 bbl/D (1,300 m3/h) of this throughput was a direct result of injecting a drag reducing additive. In 1981, drag reducers continue to contribute to the TAPS throughput.

In commercial operations, a drag reducer must be shear stable during line flow and must be effective at very low concentrations. In addition, the treated crude must not cause any downstream refining problems. CDR™ Drag Reducer meets these requirments and has proven to be a viable means of increasing pipeline flow rates.

Recent modifications of the polymeric additive have raised drag reducer performance levels. New performance data from 8, 12, and 48-inch diameter pipelines are discussed. Offshore production operations would clearly benefit from improved performance. Shipping and handling of products present a special problem in onshore operations … particularly in periods with bad weather. Reducing the required storage will proportionally reduce platform space and weight requirements.
Udang "B" Insulated Subsea Pipelines – Design and Installation
Authors: Tillinghast W. S.
Published: December 2007

The development of the Udang "B" project in the Indonesian Natuna Sea required the installation of two insulated submarine pipelines in nearly 300 feet of water. These pipelines carry 100° F pourpoint crude, water, and gas from the recently installed Udang "B" platform to the Udang "A" platform. At the Udang "A" platform, the produced fluids are processed. The crude oil is then transported to a permanently moored storage tanker through two other insulated submarine pipelines.

The Udang "B" pipelines have a 12¾ inch inner pipe with an 18 inch outer pipe. The annulus between the two pipes is filled with a polyurethane insulating foam. That annular cavity is then sealed with a steel washer plate at either end of the insulated pipe joint. The pipeline system is designed to withstand a 190° F operating temperature and to comply fully with applicable pipeline codes. The pipeline is designed so that the polyurethane insulating foam is protected from the 140 psi external hydrostatic pressure.

The pipelines were installed offshore using a lay barge with innovative methods used at the field joints to insure the uniform structural integrity of the pipeline and the continuity of the insulation system. The risers were also insulated and installed in one piece with a flanged connection completed on the seafloor to connect the riser with the pipeline. Third party underwater inspection of the jacket, risers, and pipeline connections was provided by a remote controlled vehicle (RCV).

This paper discusses the insulated pipeline system as it evolved through the design, onshore pipe insulation and joint fabrication, and offshore construction. The paper reviews the design and construction techniques used successfully for these offshore insulated pipelines. These techniques could be applicable for other similar deep water insulated pipeline applications.
Dynamic Response Of Offshore Structures
Authors: Jan Hsien Y , Chen Hsao H , Conlon John F
Published: December 2007

This paper discusses the importance of dynamic effects on load predictions and structural responses for various types of offshore structures. In addition to wave, wind and current loads, seismic and vibration analyses are emphasized for pile-supported structures. When floating platforms are considered, emphasis is focused on motion and wave load calculations. The calculation procedures and the dynamic effects are illustrated through numerical examples of both bottom-supported and floating platforms.

A sample application of 20-year hindcast wave data is given for predicting wave loads on a column-stablized unit in the Celebes Sea. Problem areas which deserve further research are also identified in the paper.
Use of the Dual Laterolog for the Evaluation of the Fracture Porosity in Hard Carbonate Formations
Authors: Boyeldieu C. , Winchester A.
Published: December 2007

In hard formations (dolomite — limestone — quartzitic sandstone or even volcanics) the matrix is often of low to very low porosity and of extremely low permeability. Such formations are only considered as potential producers when fractures and fissures drain the hydrocarbons to the well bore. It is therefore extremely important to detect the presence of fractures, and several logging toots are able to give a good and reliable information about the location and even the orientation of those fractures. The combination Dual Laterolog-Microspherical log is one of the fracture indicators used nowadays. When analysing the process of mud or mud filtrate invasion in a fractured reservoir and observing die effect on the resistivity logs it was discovered that the Dual Laterolog itself was a fracture indicator and that the difference in conductivity between the two measurements — deep and shallow was a function of the volume of hydrocarbon displaced from the fracture system during the invasion process. It allows to compute a lower limit of the fracture porosity — the technique has been successfully applied in various formations and examples are presented.
Offshore Communications
Authors: Stanzak R L , Chew C S
Published: December 2007

Telecommunications technology offers the offshore industry many alternatives to link up offshore and onshore locations to effectively coordinate offshore related activities. EPMJ's offshore communications network was developed in stages, using HF radio initially and gradually developing into the present private telephone network using LOS radio links and a troposcarter system.
Erawan Field Project Management
Authors: Nordquist R A
Published: December 2007

Union Oil Company, along with its co-venturer South East Asia Petroleum Exploration Company, were "on time" and within the original cost estimate upon start-up of gas production facilities in Erawan Field, Gulf of Thailand. This paper analyzes the planning and strategies used to achieve this task.
Development and Reservoir Engineering Studies for the Pulai Field Offshore Peninsular Malaysia
Authors: Flores J , Kelm C H
Published: December 2007

Comprehensive preliminary reservoir studies and subsequent detailed geological analysis and surveillance programs were combined to plan and implement an efficient depletion scheme for the Pulai Field. A highly sophisticated three-dimensional mathematical model was developed to provide effective reservoir management. Model predictions shown an incremental recovery of 10 1% the original oil-in-place through implementation of a gas injection scheme. Drilling of four additional wells in the two major sands provides an additional recovery of 7% of the original oil-in-place. The models will be periodically updated as production progresses and new information becomes available through development drilling. Revised predictions from the updated models will be used in our continuing optimization of the Pulai Field.
The Role of Pressure, Dipmeter and Seismic Data in Planning the Development of the Structurally Complex South Furious Field, North West Borneo.
Authors: Guest J. W. , Deckers F.
Published: December 2007

The South Furious Field is a complexly faulted, upthrust anticline with a prospective sequence consisting of a Middle Miocene, lower coastal plain clastic succession. The field is characterised by extremely incoherent seismic data from which only a late Middle Miocene unconformity can be mapped with confidence.

The dense faulting and the discontinuous nature of the reservoir sands have made attempts at log correlation virtually impossible. However, in the Eastern Area of the field an extensive set of RFT derived pressure data has revealed several correctable pressure zones. The pressure zones have defined at least six major accumulations and several minor ones. Furthermore, at least two different aquifer regimes have been identified.

Early seismic interpretations, although unable to resolve the structural complexity of the prospective sequence, noted a correlation between hydrocarbon bearing intervals in wells and the occurrence of low frequent ‘wormy’ shaped reflections on seismic sections. In area without well control such anomalies were used as hydrocarbon indicators. These together with the pressure zone correlations and a simplified faulting pattern derived from HDT interpretation were used to construct maps of the top seals of each of the major accumulations.

The maps derived from this approach have been used for development planning, well targetring and oil-in-place estimations.
Arun Field Development Phase
Authors: Seipel J. R.
Published: December 2007

Following discovery of the Aran Gas Field in 1971 and subsequent appraisal drilling to obtain essential reservoir data, a development project based on delivery of sufficient gas to supply a six train LNG plant, with a coincident cycling operation, was planned. High wellstream temperatures, pressures, gas throughput rates and corrosive CO2 content, placed producing, safety, security and environmental constraints on the design of surface wellstream gathering and processing facilities and led to the selection of the cluster development concept.

Producing capacity, dedicated to LNG plant demand, has resulted in a two phase field development program. Program I, consisted of two producing clusters each containing two producing trains and five high rate gas wells, a central control and power site (point "A"), a gas cycling system consisting of three injection compressors, eight injection wells and injection lines, and a 16-inch condensate transmission pipeline to the LNG plant. Production from the two clusters has supplied the three train (first phase) LNG plant, completed in late 1978, and the Arun Field cycling project. Program II commencing in 1981, will provide for an additional two producing clusters, each consisting of two producing trains and six producing wells, as dictated by the LNG plant expansion program.

This paper will provide an overview of the Arun Field production mode design concepts, detail the problems encountered in the surface producing facilities following start-up, i.e. corrosion, separator carryover and recycling compressor limitations, and define how these problems have been, or are being, resolved. This will include a projection of anticipated equipment modifications and additions which will be required to accommodate to changing reservoir conditions during the producing life of the Arun Gas Field.
The Krisna High: Its Geologic Setting And Related Hydrocarbon Accumulations
Authors: Ardila L. E.
Published: December 2007

The Krisna Field, located on the western flank of the Sunda Basin, constitutes one of the most significant petroleum discoveries by PERTAMINA-IIAPCO in the Southeast Sumatra Production Sharing Contract Area. The oil accumulations found to date are associated with the "Krisna High", an old paleotopographic basement high which in late-Oligocene time acted as a source of terrigenous material and later became a favorable site for the growth/sedimentation of reefal carbonates. Deposition of the reservoir rocks took place mainly under transgressive conditions, although some regressive pulses have been recognized. As the rate of transgression of the "Krisna High" increased, reefal growth could not keep pace and ceased.

Hydrocarbon accumulations found on the "Krisna High" are mainly of a stratigraphic nature; however, the structural component in some instances plays an important role.

Geochemical data indicate that Krisna hydrocarbons were generated in the Sunda Deep. Therefore, moderate-to-long distance migration is postulated via the basal unconformity and major fault zones.

A preliminary interpretation of the relationship between facies distribution and porosity development is presented in the discussion to follow. Porosity in the reservoirs is mainly secondary, and is associated with low energy back-reef facies.
Effects of Pentadiagonal Matrix Ordering Schemes on Iterative Methods
Authors: Cheng M. C. "Aaron"
Published: December 2007

It is well known that the ordering of the unknowns on a finite-difference grid had effects on the computing efficiency of direct matrix solution methods. In reservoir simulation, diagonal ordering scheme (D2), alternating point ordering scheme (A3), and alternating diagonal ordering scheme (D4) have been found theoretically and experimentally to improve the performance of Gaussian type direct solution methods. This paper investigates the effects of D2, A3 and D4 ordering schemes on the performance of iterative matrix methods. The test model is the typical two-dimensional parabolic partial differential equation with Neumann type boundary conditions and the iterative method used is the point successive overrelaxation (PSOR). Ten different cases are presented.
An Automatic Time-Step Selector For Reservoir Models
Authors: Mehra Rakesh , Hadjitofi Michael , Donnelly John K.
Published: December 2007

This paper presents an algorithm for the selection of an optimal time step sequence for use in a thermal simulator. The algorithm is based on the observation that a solution vector always tracks the locus of stationary points on the surface mapped by the residual function. This provides a simple relation for obtaining a sensitivity vector which is then used to determine a time step length that gives a global error of the norm less than the prescribed tolerance. In addition, the sensitivity vector is used to seek a close initial solution for Newtonian iteration. When applied to practical problems the numerical scheme results in substantial computer cost savings.
The Evaluation of Interblock Mobility Using a Modified Midpoint Weighting Scheme
Authors: Yoshiaki Ito
Published: December 2007

A modified midpoint weighting scheme is a technique which can be used for increasing the accuracy and stability of finite difference numerical simulations. Generally, if midpoint weighting is used to evaluate the transmissibility at an interface between adjacent blocks, explicit methods may not produce the correct solution and implicit methods may lead to an oscillatory behavior. Reasons for this behavior have been investigated and it has been found that these problems occur because of numerical limitations during accumulation of the displacing fluid within the upstream block.

A proposed modified version of midpoint weighting appears to eliminate this problem and several linear displacement test runs have indicated that the local truncation errors are comparable to those in the two-point upstream weighting scheme. The overall accuracy of results in areal systems appears to be better than the two-point upstream scheme the use of which is constrained due to its assymetric character. The results were also compared to the single-point upstream weighting method and it was found that the modified midpoint weighting scheme allowed the use of a coarser grid while maintaining similar accuracy. An additional advantage to this new technique is that it can also be used in an implicit formulation.
The Use of Variable Weighting to Eliminate Numerical Diffusion in Two-Dimensional Two-Phase Flow in Porous Media
Authors: Lasseter Thomas James , Karakas Metin
Published: December 2007

A simple numerical method has been developed that largely eliminates numerical diffusion errors associated with saturation discontinuities or shocks for two-phase flow in one and two dimensions. The important aspect of the approach is the computation of a variable weighting factor for the interface fractional flow between grid blocks. In order to eliminate numerical diffusion at shocks, the appropriate weighting has been found to be downstream weighting just ahead of the shock and upstream weighting otherwise.

In one dimension, the Buckley-Leverett problem as well as the motion of an oil bank and a more general initial saturation have been analyzed. In two dimensions, five-spot pattern floods with both homogeneous and heterogeneous permeability distributions have been modelled.

In all cases examined, shocks are confined to a single grid block in the direction of flow. Numerical diffusion is present only where there are steep saturation gradients that are not shocks.

The approach appears to be generalizable to the multicomponent, multidimensional case including gravity and capillarity.
Finite Elements With Characteristics for Two-Component Incompressible Miscible Displacement
Authors: Russell Thomas Fletcher
Published: December 2007

An efficient method for modeling convection-dominated flows is presented and applied to miscible displacement in a porous medium. The method uses characteristics to model convection and finite elements for diffusion and dispersion, thereby treating each physical process with a well-suited numerical scheme. A finite difference analogue can also be formulated.

Numerical results are given that show that the method can simulate adverse mobility ratio displacements accurately without suffering from grid orientation, numerical dispersion, or overshoot. The use of characteristics allows time steps to be an order of magnitude larger than in previously proposed methods, with a corresponding increase in efficiency. Unlike many procedures utilizing characteristics, this method is easily applied in two or three dimensions.
Simulations of Chemical Flooding—Comparison with Experimental Data
Authors: Carney Bruce , Finlayson Bruce A.
Published: December 2007

A compositional simulator is used to model chemical flooding. Computed results are compared to laboratory studies available in the literature. Special representations were devised to model the surface tension and phase behavior of Types II(-) and III on ternary diagrams. Continuous core-flood experiments of Healy, Reed and Carpenter8 were modeled. Results from models with high dispersion levels compare favorably to the data for cumulative recovery and fractional flow of oil with several different injection compositions. Core-flood experiments of Willhite, Green, Okoye and Looney9 have been simulated for situations involving a slug injection of microemulsion. Results obtained for models with high dispersion levels compare favorably with experimental data for cumulative recovery and fractional flow of oil. Surfactant and alcohol concentration profiles are not well modeled because the ternary phase diagram is not appropriate to this system.

The model parameters were then changed to allow a sensitivity analysis. For parameters representative of these laboratory studies the results are not strongly dependent on the dispersion level. Standard data was used for relative permeability, and the detrapping parameters can be changed to simulate other cases or to improve the comparison with experiment.
Reservoir Simulation and the In-house Vector Processor: Experience for the First Year
Authors: Killough J. E. , Levesque J. M.
Published: December 2007

Over the past year, ARCO Oil and Gas Company has had the first large scale in-house vector processor (the CRAY-1S) in the oil industry. During that time, a considerable effort has been spent on conversion of reservoir simulator codes to perform efficiently in a vector processor environment. The following paper describes some of the more important aspects of these experiences during the past year. The vector strongly implicit procedure algorithm is presented along with timing comparisons. A unique method for vectorization of a compositional reservoir simulation model is also presented. The paper discusses difficulties with the IBM/CRAY interface and how these were overcome. Finally, a method is described for utilizing the capabilities of the CRAY-1S I/O processor for problems that are not contained in memory.
Vectorized Direct Solvers for 2-D Grids
Authors: Calahan Albert Donald
Published: December 2007

The performance of direct equation solvers useful in the solution of elliptic problems on a plane with the CRAY-1 are reviewed. Included are comparisons of software associated with natural, alternate diagonal, and dissection equation orderings.
The Kuparuk River Field: A Regression Approach to Pseudo-Relative Permeabilities
Authors: Johnson J. B. , Nanney Michael M. , Killough John E. , Lin Y. T.
Published: December 2007

The Kuparuk River field located about twenty-five miles west of the Prudhoe Bay Unit, North Slope Alaska, represents a large accumulation of oil spread over a wide areal extent. The large areal extent of the reservoir presented a major difficulty for full scale reservoir simulation of this field especially under waterflood conditions. To overcome this difficulty a regression approach was used to match finely-gridded, three-dimensional waterflood models with coarse-grid models. Matches were obtained by varying in an optimal manner the pseudo-relative permeability relationship and the interblock weighting of relative permeabilities. It was found that for both the waterflood case and the reinjected gas displacement case excellent matches of the finely gridded model results could be obtained with an extremely coarse-gridded model. Matches were obtained automatically using a non-linear regression approach in a relatively small amount of computer time. In addition, sensitivity analysis showed that the pseudo-relative permeabilities thus generated were insensitive to reasonable variations in waterflood rate and to timing of waterflood initiation. With this technique it was possible to construct a fieldwide model for facilities planning and to study the effect of facilities on ultimate recovery from the reservoir.
An Analysis of the Estimation of Reservoir Properties from Waterflooding Data
Authors: Watson A. T. , Gavalas G. R. , Seinfeld J. H.
Published: December 2007

The estimation of porosity, absolute permeability and relative permeabilities from pressure drop and production data is considered for water-oil flow in a linear reservoir. We examine some of the related fundamental questions associated with this history matching problem, namely which of the above properties can be estimated, in principle, from pressure data, water-oil ratio data, or both, and how accurately can they be estimated. Analytical expressions derived by extension of Welge's method to heterogeneous reservoirs are used to study the estimation of porosity and absolute permeability distributions. A sensitivity analysis and an error covariance analysis are employed to study the feasibility and accuracy of estimating relative permeability parameters.
Effects of Diagenesis on Pore Texture and Petrophysical Properties of Sandstone Reservoir and Its Geological Significance
Authors: Guohua Zhu
Published: December 2007

This paper deals with diagenesis of Yan-10 Sandstones, Yanan Series, jurassic—the main producing horizons in an exploratory area in Shan-Gan-Ning Basin. The effects of diagenesis on pore texture and petrophysical properties of sandstone, its effects on forming trapping conditions for oil pools, the genesis of low permeability zone near the oil-water boundary, as well as secondary pores together with authigenic clay minerals of sandstone are presented. Furthermore, the paper describes briefly Yan-10 sandstones in some other areas.
Bottom Hole Assembly Problems Solved by Beam-Column Theory
Authors: Jiazhi Bai
Published: December 2007

The bending portion of a multiple-stabilizer bottom hole assembly can be considered as a string of several simply-supported beams loaded by axial compressive forces together with transverse ones. By the beam-column theory, a system of "equations of three moments" can be obtained. The essential aim to design a bottom hole assembly with special requirements is to produce a desirable reactive side force on the bit from the formation. While there are numerous parameters that would influence the value of this force, the effect of each of them can be evaluated from the position it occupies in those equations. This paper is particularly focused on the analysis of pendulum assemblies with two stabilizers and affirms their obvious advantages over those with only one stabilizer or no stabilizer.