bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Flow Rate and Wettability on Water-Oil Relative Permeabilities and Capillary Pressure
Authors: Labastie Alain , Guy Maurice , Delclaud Jean P. , Iffly Rene
Published: December 2007

In order to properly account for wettability and oil trapping, laboratory waterflood experiments need to be carried out with reservoir fluids and at reservoir flooding velocities.

An interpretation procedure has been defined for such measurements with the help of phenomenological experiments conducted under laboratory conditions with an apparatus allowing direct measurements of saturation and pressure in each phase at different points in the core. Experiments can be interpreted with no ambiguity.

They indicate that relative permeabilities are independent of flow rate except near the residual oil saturation. Capillary pressures however depend on flow rate and porous medium wettability: –in some porous media (mainly sandstones), the imbibition capillary pressure always remains positive and changes very little with the flow rate;–in other media (mainly carbonates) the capillary pressure, which is generally positive during the initial oil drainage phase, becomes negative immediatly behind the water front. The higher the waterflooding rate the more negative the capillary pressure. This makes it impossible to correctly interpret waterflooding experiments using static capillary pressure data.

As direct measurement of dynamic capillary pressure is not feasible for experiments carried out under reservoir conditions, a procedure, based on the preceding conclusions was developped to interpret such experiments. By combining the results of experiments at high velocity and at low velocity it is possible to determine relative permeabilities, residual oil saturation, dynamic capillary pressure and accordingly wettability.
Electromagnetic Propagation Logging: Advances in Technique and Interpretation
Authors: Wharton Russell P. , Hazen Gary A. , Rau Rama N. , Best David L.
Published: December 2007

The Electromagnetic Propagation Tool (EPT*) is a downhole microwave instrumentation device which channels 1.1 GHz energy into the formation and measures the travel time and attenuation of the microwave signal as it propagates through the invaded zone. The relevant electromagnetic field theory, the basic measurement technique, and the tool block diagram are reviewed. The present interpretation techniques are then discussed, followed by several log examples which show the utility of the EPT. Specifically, the EPT-derived porosity, when compared with neutron/density porosity, allows one to distinguish between hydrocarbon-bearing and water-bearing zones in formations having varying lithologies and water salinities.
Predicting the Hydraulically Created Fractures in the Cotton Valley Formation of East Texas
Authors: Brown Russell O. , Forgotson James M. , Forgotson James M.
Published: December 2007

The tight gas sandstones of the Cotton Valley Formation of East Texas require massive hydraulic fracture treatments to achieve economic rates of production. Engineering data indicate a well will efficiently drain a maximum of 160 acres. Optimization of well spacing will require a knowledge of induced fracture orientation. At the present time there is no reliable method whereby this orientation can be measured.

Oriented caliper data obtained from dipmeter logs run in fifty wells were used to investigate the borehole geometry through the Cotton Valley sandstones. It was found that quite often the sandstones when drilled through would "spall" or "wash-out" and that the borehole would be elliptical in shape with the major axis always oriented in a NW/SE direction. The opinion of the authors is that the consistency in orientation is due to in-situ stresses within the rock, and a prediction can be made that hydraulically induced fractures in the Cotton Valley sandstones of East Texas will be oriented in a NW/SE direction.
Flexibility - A Requisite For Successful Change
Authors: Hosford E.
Published: December 2007

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

Today we are living in a world where change is expected - the frequency and rapidity with which it happens has been astounding and, to some perhaps, alarming. The recent trips into space, the evolution of nuclear energy, and the application of electronics are only a few of the most recent developments which are affecting our lives. Possibly not as spectacular as these but contributing as much as these, but contributing as much to our living standards, and certainly of more significance to those assembled here today, are the changes which have been and are occurring in the petroleum industry.

Every great change has had behind it some strong motivation. The change that came after Spindletop was motivated by an availability of oil that was suited to be used as fuel. Prior to that time, only a small portion of the oil had been consumed as a fuel.

The great change in the "30's" came about as a result of a demand for conservation and the end of wasteful practices.

Today's change is the direct result of competition.
The Availability of Water for Oil Shale Development in the Upper Colorado River Basin
Authors: McDonald J. William
Published: December 2007

It is estimated that the water demands of an oil shale industry of about 1.5 million bbl/day, as well as the water demands of the associated growth,2 could be satisfied from surface supplies without having to significantly reduce other existing or projected consumptive uses in the Upper Colorado River Basin (see fig. 1). This conclusion is premised, however, on four major qualifiers.

First, surface water supplies can be made available for the development of oil shale only if: water not presently under contract is purchased from existing U.S. Bureau of Reclamation reservoirs; and/ornew reservoir, pipeline, and pumping facilities are constructed in order to capture, store, and transport the water.

For a 1.5 million bbl/day industry, a crude estimate of the capitalized cost of developing the necessary surface water supplies is $1 billion. This would be not more than 1 or 2 percent, if that much, of the capitalized costs of constructing and operating the oil shale facilities proper.
Post Fracturing Behavior of Fracturing Gels and its Influence on Fracture Closure and Proppant Distribution
Authors: Hannah Robert R. , Harrington Larry J. , Potter John S.
Published: December 2007

This paper reports on a series of tests performed on crosslinked fracturing gels. The purpose of the test series was to measure certain effects of oxidizing breaking agents on these fluids. Specifically, we hope to find: The effect of breaking agents on the fluid’s rheological properties.How these agents affected the fluid’s ability to support proppants.Do oxidizing breakers change the fluid loss coefficient of crosslinked fracturing gels?

The equipment used in these experiments included a Fann Model 50C viscometer, a Fann Model 39 viscometer, and a modified Baroid fluid loss cell.

The findings of this study are: As expected, breakers have an adverse effect on the rheological properties of these gels over and above normal thermal and shear degradation.The perfect proppant support of these fluids is shortened and is broadly related to some lower limit rheological properties but is more specifically related to the breaker concentration in lb breaker/lb polymer/1000 gal. No specific relation was found to polymer concentration as long as equivalent breaker loadings were used.These agents had very definite effects on the fluid loss characteristics of these gels. The test series demonstrated that in prolonged testing of fluid loss versus the square root of time that slope changes occurred at least once and in longer tests, twice. In the series of tests where two changes of slope occurred, the final slope possibly signals a change from wall control (CIII) to viscosity control (CI).

All tests in this series were run at a temperature of 180°F (82°C).
Characterization of Hassi R’Mel Reservoir Rocks by an Unconventional Method Using Well Logs and Core Analysis Data
Authors: Ghalem Tahar , Blanc Georges , Sabathier Jean-Claude , Rocca Marc
Published: December 2007

A good reservoir description is the necessary first step before building a reservoir simulation model.

This paper describes an unconventional method of rock reservoir characterization in which open-hole logs and core analysis are conjointly taken into account.

The method allows to split up all reservoirs rocks encountered in the giant HASSI R’MEL gas field into thirteen LOG FACIES classes or clusters which are identified by their log readings (the selected log suite is composed of CNL, FDC and Gamma Ray logs).

The geological and the petrophysical meaning of each class has been cross-checked with lithological observations, core analysis data and conventional log interpretation.

Based on seven key wells in the first step, the method was then extended to 129 wells for which the same log suite was available.

The use of mean petrophysical figures (porosity, shaliness and water saturation) for each log facies led to a reservoir evaluation well by well in terms of gross and net thickness, porosity and gas in place.

The areal characterization of each reservoir level was then studied on the basis of the vertical location of non reservoir classes.

This method which is operating through the CLASL0G computer system is quite general and could be applied to any other field.
The Role of Well Logs in Reservoir Modeling
Authors: Raymer L. L. , Burgess K. A.
Published: December 2007

Wireline well-logging measurements are one of the richer sources of petrophysical data for input into and control of reservoir simulators. Besides providing many of the petrophysical parameters required in the design of reservoir models, logs complement, expand and verify data from other sources; afford insight into geological characteristics: and provide acceptable estimates of reservoir parameters normally obtainable elsewhere but not always readily available.
Salinity and Hardness Tolerant Microemulsion Formulations
Authors: Maini Brij B. , Batycky Jim P.
Published: December 2007

The optimization of surfactant formulations has involved varying the salinity of an NaC1 brine for a selected reservoir oil-surfactant-cosurfactant combination. Use of the resulting optimal salinity mixture in a particular reservoir has necessitated the injection of low salinity preflush slugs to precondition and alter the reservoir environment. However, limitations in the level of success than can be expected occur due to the presence of poor sweep efficiencies within an invariably heterogeneous reservoir and the persistence of hardness or multivalent ions which both become magnified in the presence of larger interwell spacings, as is typical in Alberta reservoirs.

A more plausible approach to the design of surfactant slug compositions is one that involves matching reservoir oil-reservoir brine pairs to suitable combinations of surfactants and cosurfactants. An extensive screening of combinations of anionic and nonionic surfactant materials was conducted using two hydrocarbons, n-octane and a mineral oil, and synthetic brines that ranged in salinity from 2% to 20% total dissolved solids. The ratio of Na:Ca:Mg was kept at 20:2:1, since this typifies a large number of reservoir brines.

Phase behavior studies were conducted to establish conditions needed to form middle-phase microemulsions which contained surfactant concentrations in the 5% to 15% range and which did not reveal the formation of insoluble materials at either interface. These phase behavior studies involved the mixing of surfactant mixtures with equal volumes of oil and brine in order to determine the amounts of oil and/or brine solubilized into a surfactant-rich or microemulsion phase.

Promising formulations were composed of combinations of either a single ionic and two non-ionic surfactants or two ionic and one non-ionic surfactant. The principle anionic surfactants that were examined included both synthetic and petroleum sulfonates, but once a compatible cosurfactant pair had been identifed the particular sulfonate chosen became immaterial.

Interfacial tensions measured between adjacent phases, which were in the millidyne region, also proved to be relatively insensitive to salinity scans.
Modeling Natural Gas Reservoirs: David vs. Goliath
Authors: Collier Richard S. , Monash Ellis A. , Hultquist Paul F.
Published: December 2007

For many years it has been standard practice to use very involved grid models to describe the reservoir behavior for the oil and gas industry. These grid models represent sizable investments in both time and money and are used in many instances in a sparing manner so that the cost of getting the needed reservoir information does not become prohibitive. In this paper we present an alternative model for a gas reservoir that is averaged over the geometry of the reservoir and hence represents a "zero-dimensional" model. It is called a "reservoir per se" model and describes the state variables as space averages through time.

"David" is thought of as a small, efficient, low cost and low maintenance model that can be used as a simple alternative to, or prelude to, the use of the larger grid or "Goliath" type models. "Goliath" is pictured as big, bulky, not very efficient, high cost, high maintenance, and needing large amounts of input data.

The particular "David" model — the reservoir per se model — that is presented does a good job in describing the bulk properties of the gas reservoir and has been validated in eighteen distinct cases. This model can and should be used when "simple" reservoir answers are needed quickly and at low computer cost.
Gas-Condensate Flow in Perforated Regions
Authors: Jamiolahmady M. , Danesh A. , Sohrabi M.
Published: December 2007

The most crucial region affecting well productivity is the perforated region. Considerable effort has been directed to study this subject, mathematically by many investigators, but they are mainly focused on single-phase flow with limited information on the two-phase flow systems.

It has been demonstrated, first by this laboratory and subsequently by other researchers, that the gas and condensate relative permeability (kr) can increase significantly by increasing the flow rate, contrary to the common understanding. This effect, known as positive coupling, complicates the flow of gas and condensate near the wellbore even further when it competes with inertial forces at higher velocities typical of those around perforation tips.

The flow of gas and condensate in perforated regions was studied in this work using a finite-element modelling approach. The model allows for changes in fluid properties and accounts for the positive coupling and negative inertial effects using a fractional flow based relative permeability correlation. A sensitivity analysis on the impact of perforation characteristics such as density, phasing, length and radius as well as that of fluid properties, rock characteristics, wellbore radius, fractional flow and rate on well productivity was conducted resulting in some valuable practical guidelines for optimum perforation design.

The results were expressed in terms of the productivity ratio, PR, defined as the ratio of the total flow rate of gas and condensate in the perforated completion to that of an unperforated open-hole for the same pressure drop. The results indicated that PR is independent of fluid properties, fractional flow and rates for most practical purposes.
A TLP Well Design
Authors: Goldsmith Riley G.
Published: December 2007

This paper describes the design, installation, and operation of the drilling, completion and production equipment used with the Conoco TLP well design. This TLP is securely fixed on location which permits "modified conventional platform type" completions with the Christmas trees on the platform. The production and completion systems are discussed to point out the many similarities and explain the few differences from conventional platform systems. Components that are unique to the TLP systems, such as riser tensioners and tieback systems, are described. The TLP deck designs and well arrangements are described. The TLP drilling system, with high pressure drilling riser, platform BOPS and tensioner, is described. A description is also presented of the offtake "sales riser" system.
CO2 Injection for Enhanced Gas Recovery and Geo-Storage: Reservoir Simulation and Economics
Authors: Al-Hashami A. , Ren S. R. , Tohidi B.
Published: December 2007

CO2 can be injected into gas reservoirs for enhanced gas recovery. The main benefit of CO2 injection is pressure support to prevent subsidence and water intrusion. Enhanced gas recovery can be via both displacement and repressurisation of the remaining natural gas. The objective of this paper is to investigate the process of injecting CO2 into gas reservoirs using a compositional reservoir simulator. The effects of gas mixing, CO2 diffusion and CO2 solubility in formation water are investigated. Simulation studies are performed to assess the sensitivity of various design and operating parameters to the process. In general, an incremental gas recovery of 8% can be achieved by CO2 injection for a reservoir with a primary recovery factor of 85% by natural depletion. Economic feasibility of CO2 project is also investigated. The profitability of the project is sensitive to gas price, cost of CO2, original gas composition in the reservoir, and further processing of the produced gas.
Shifting the Gaussian Curve to the Right – A Fully Stochastic Approach to Marginal Offshore Field Development
Authors: Graf T. , Henrion H. , Bellavance R. , Fernandes J.
Published: December 2007

A significant part of any field development planning exercise resides in adequately quantifying reservoir uncertainty, particularly when information availability is limited. For marginal fields, accurate appraisal of the project downside becomes even more crucial, as different development options carry a substantial probability of negative net-present-value and project economic viability relies on reservoir risk minimization.

It then becomes imperative to undertake a complete and detailed risk analysis in order to identify key contributors to reservoir uncertainty, and determine their combined effect and impact on asset economics. A thorough understanding of the risk-setting can lead to better focused resource allocation, data acquisition and identification of management solutions. This will then help mitigating against uncertainty and shift to the right and/or narrow the distribution of recovery and net-present-value. The evaluation and quantification of the impact of key uncertainty factors is exacerbated by the multiplicity of combinations in development options and can only be represented by a very high number of numerical simulations. It is only with today's computing power and recent software developments, in stochastic data analysis and statistical optimization, that it is possible to quickly and exhaustively encompass all relevant uncertainty parameters.

The following case of a marginal offshore field in Angola illustrates the successful application of a stochastic planning approach in defining the optimum field development strategy. A novel workflow in stochastic analysis was applied allowing proper identification and mitigation of all relevant risk factors. This resulted in the determination of optimum surface facilities dimensions, well locations, drilling plans, wellhead structure locations, coring programs and logging suites. This methodology was key in establishing an economically viable option in this high cost, high-risk area.
Geophysical Logging and Exploration Techniques in the Appalachian Coal Fields
Authors: Miller Marshall S. , Moore Mackey
Published: December 2007

The Appalachian Region, although developed heavily in the past 75 years, remains as a tremendous source of future coal reserves. However, with the thicker and more accessible coals now well developed, the coal industry is adjusting rapidly to new exploration techniques for defining new thin coal reserve potentials. Many of these techniques have been derived from the oil and gas exploration industry, while others rely on applications of depositional modeling.

Extremely high resolution electric logging (EHR) is fast becoming an integral part of exploration programming. With very small diameter design and simple construction, the logging tools are providing "in-place" thickness and parting measurements in extraordinary detail. Rock and bone partings within coal seams are now being defined to within less than an inch. Ash quality of the seam is also well defined by these new probes, as well as roof and floor rock competency, and percent reject within the seam. The high resolution electric logging process is also establishing new reserves where previous poor coal recoveries had left conservative impressions.

The more detailed data being generated by electric logs and the increasing knowledge of paleo-depositional environments strongly suggest the need for a revision of present reserve classification systems. This is particularly true for thin (28 to 36 inch) seams, where a loss of a few inches is critical to economical mining. A new reserve system, based on depositional environments, is suggested in this paper.
Early Implementation of A Full-Scale Waterflood in the Abo Reef, Terry Co., Tx – A Case History
Authors: Benton Jerry P. , Maslanka Paul M. , Smith Robert L.
Published: December 2007

The Kingdom Abo Reef Field, located in the northwestern portion of Terry County, Texas is a relatively recent discovery along a linear organic bank trend which is intermittently productive from Eddy County, New Mexico to Hockley County, Texas (Fig. 1). Gulf Oil Corporation operates a major portion of the Kingdom Abo Reef Field, thus enabling Gulf to rapidly apply the technology that is highlighted in this paper.

The first part of this paper deals with the history and initial development of the field with the objective of providing a basis for a waterflood project. The emphasis is placed not on the development of new technology, but rather the application of existing technology in characterizing the reservoir to assist in the early recognition of a low primary recovery factor. An analysis of basic data taken during development and early production operations led to the conclusion that primary operations would result in a low primary recovery, which provides the setting for the waterflood feasibility study. The description of the waterflood feasibility study emphasizes the specific methodology employed to predict the waterflood performance. The physical development of the waterflood is discussed which emphasizes both the infill expansion project and the water-injection systems. The paper concludes with a discussion of the present operations and a review of the flood’s performance.

Interest in Abo carbonate reservoirs began with the discovery of the Lovington Abo Field in Lea County, New Mexico in 1951. Subsequent discoveries were made in the Empire Abo Field in 1957 and Vacuum Abo Field in 1960 along what is today called the Abo Reef Trend. It is along this geologic trend in Terry County, Texas that the Kingdom Abo Reef Field is located.
Mineralogical Analysis and Uranium Distribution of the Sed Imentary-Type Uranium Ores
Authors: Fishman Paul H. , Huang Wen H.
Published: December 2007

Nine cores and approximately 200 samples from a sedimentary-type uranium ore body of the Upper Jackson formation located in Karnes County, Texas were studied to determine the stratigraphy and the mineralogy, in relation to the uranium distribution. The ore body is generally a fine-grained, gray, well-sorted arkosic sandstone enclosed in finer-grained, poorly-sorted lagoonal or paludal mudstone or lignite. The deposi-tional environment of the ore body is presumably a beach-barrier-bar sequence. The bulk mineralogy consists primarily of quartz, and feldspars with minor amounts of biotite, muscovite, augite, clinoptilolite and very minor amounts of hematite, pyrite and cof-finite. The clay analysis reveals a preponderence of smectite with very minor amounts of kaolinite and illite.

High concentrations of uranium are generally associated with a high concentration of clays, zeolites and/or carbonaceous material. Additionally, uranium concentration usually increases with a decrease in size fraction. Thus, the expandable and absorptive smectite and/or the absorptive and ion exchangable zeolites could play a significant role in uranium mineralization.
Natural Gas Price Regulation - Its Problems and Prospects
Authors: May Henry S. , White Carol A.
Published: December 2007

The Natural Gas Policy Act of 1978 (NGPA), is frequently accorded the dubious distinction of being the most complex, ambiguous, and internally inconsistent piece of legislation ever passed by Congress. This paper will take a brief look at the history of natural gas pricing policy, analyze the ways in which the NGPA fits into this historical perspective, discuss the achievements and shortcomings of that statute and speculate about the future of natural gas regulation.

Few would disagree that from a standpoint of economic efficiency and public policy decontrol of at least new natural gas is warranted. The simple fact is that if the price level for natural gas is kept artificially low, there will be less natural gas produced than the demand for it. Despite what is coming to be an increasing perception that deregulation would be generally beneficial, the NGPA fell far short of the ultimate goal of deregulation. In order to understand why political reality has not kept pace with economic reality it would be helpful to briefly consider the history of natural gas regulation.

In 1954 the Supreme Court extended FPC regulation to the wellhead price of natural gas sold for resale in interstate commerce.1/ During the seven years following the Phillips decision there was little indication of a disequilibrium in the supply and demand of natural gas. Indeed, during the 1950's the supply of natural gas continued to increase as it had since World War II and increase dramatically. During this period, natural gas was still largely a by-product of the exploration for and production of oil, so that the relative availability of gas was not dramatically affected by federal price controls. Although economists and the gas industry at times raised dire forewarnings of the longterm adverse effects of price control, the immediate, practical effect did not appear particularly severe.
The Development Decision: Frontier Areas
Authors: Warren Joseph E.
Published: December 2007

Production development in a frontier area subject to adverse environmental conditions-–deep and/or stormy water far from shore or remote arctic regions--will generally require a massive capital investment. The magnitude of this expenditure, per se, will provide sufficient incentive to optimize the design of the production system before making a decision. However, owing to political and economic pressures, the development decision-–to commit to the implementation of a specified design--will usually be required at a time when estimates of reserves, well productivities, prices and costs are quite uncertain. It will be necessary, therefore, to account explicitly for the uncertainty in the decision-making process.

In this paper, a realistic procedure that allows the development decision to be approached in a consistent, rational manner is presented in detail; e.g., Quantification of the uncertainty associated with the Individual parameters--particularly, reserve and well-productivity estimates.Determination of the optimal design parameters for a particular level of reserves based on the specified economic criterion.Specification of the optimal level of reserves to be used to establish the final design which stipulates the capital investment, number of wells and maximum production rate (facility capacity).Evaluation of the expected value of the economic criterion specified for decisionmaking purposes-–and characterization of the uncertainty involved.

To illustrate the use of the suggested procedure, several numerical examples are included-–and, some heuristic simplifications are indicated. The examples are structured to show the significant effect of the tax regime on the development decision.
North Sea Associated Gas Economics: The Reliability of Complex Systems
Authors: Spanning Aller
Published: December 2007

Gas conservation and utilisation are prominent objectives in the development of North Sea oil fields. In fields like Brent, the composition and large volume of associated gas, together with regulatory, commercial and reservoir management considerations have led to the construction of offshore gas handling plant of great complexity.

The reliability characteristics of individual system components form an inadequate basis for predictions of total system behavior. Yet, for several years before the system will be fully commissioned this very behavior represents a vital input to the decision making process: sales contract volumes need to be determined and system vulnerabilities need to be identified.

The paper describes how an integrated Monte Carlo simulator was designed and built to fill the specific requirements of economic evaluation, commercial planning and regulatory compliance.

Setting, layout and operating modes of the four-platform Brent gas handling system are briefly discussed. The paper then outlines model objectives, input data requirements and simulation techniques. Specific features discussed in some detail are the implementation of real-world operating priorities and secondary system limitations in the model. Application examples discussed to illustrate the use of the model include the analysis of sales contract shortfall risk as a function of nomination level and the economics of system modifications.
Decision Parameter Evaluation for Offshore Field Development
Authors: Asheim Harald A.
Published: December 2007

Parameter estimates affect both the optimum field development decisions and the economic result. A general methodology for assessment of the effects of parameter uncertainty in offshore development decision situations is proposed, and used to analyze aspects of the initial development situation for the Statfjord field.
Waste Water Treatment Facilities and Disposal Well Injection System
Authors: Al-Arfaj Khaled A. , Nomitsu Takeshi
Published: December 2007

In order to eradicate the chances of sea and land pollution, Arabian Oil Company have introduced wastewater treatment facilities and disposal well injection system, where this system will treat different kinds of oily contaminated industrial wastewater and produce a quality of water which can be readily disposed of into a chosen subsurface formation.

With all the difficulties that would have been expected for treating different kinds of incompatible wastewater, the system have been started up and put into service successfully since October 1979.
Seismic Data in Sand Dune Regions: Data Quality in the Rub-al-khali
Authors: Shamlan Abdullah A. , Hibshi Mohammed B. , Lang Douglas G. , Preston Maurice W. J.
Published: December 2007

When seismic lines traverse major sand dunes, data acquired beneath the dunes is often of such poor quality as to render the data unuseable.

Experiments conducted by the Saudi Arabia Ministry of Petroleum and Mineral Resources and Petty-Ray Geophysical resulted in a method of computing static corrections which greatly enhanced the quality of sub-dune data.
Jurassic Arab-C and -D Carbonate Petroleum Reservoirs, Qatif Field, Saudi Arabia
Authors: Wilson Augustus O.
Published: December 2007

The Arab-C and -D reservoirs in the Qatif field are carbonate members of cycles which deposited shallow marine carbonate sediments capped by regressive sabkhah anhydrites. The impermeable capping anhydrites prevented subsequent extensive fresh water influx and thus prevented extensive late diagenetic cementation. As a result, much primary and early diagenetic porosity has been preserved. The Arab-D carbonates are mostly fine grainstones which were deposited in current-swept shelf environments and later extensively dolomitized. The dolomitized grainstones are the best Qatif Arab-D reservoir rock. The Arab-C carbonates consist of a lower transgressive oolite-mollusc grainstone facies (with high primary porosity and high permeability), a middle regressive lime mudstone – algal boundstone facies, (ranging from tight to moderately porous and permeable), and an upper slowly transgressive Clypeina algal and peloid facies (with high primary and moldic porosity and good permeability).
Application of An Air-Drilling Package in Oman
Authors: Cobbett James S.
Published: December 2007

In order to reduce water requirements for drilling on their desert concession area, Petroleum Development Oman (P.D.O.) made a 12-month trial of air-drilling techniques. By using foam as a circulating medium, top-hole sections can now be drilled with only 30 bbl/hour water-supply, where previously 500 bbl/hour were needed to drill with total losses. Cores of friable, fractured formations have also been successfully taken using foam as circulating medium, where previous attempts at coring failed. So successful were the trials, that the initial contract has now been indefinitely extended so as to include an air-drilling package as a permanent part of the drilling fleet.
Stochastic Methods in Reservoir Engineering
Authors: Cekirge H. M. , Kleppe J. , Lehr W. J.
Published: December 2007

The field parameters used for predictions of hydrocarbon reservoir behavior are obtained through field and laboratory experiments. Some of these parameters have a distinct random nature. This random character influences the predictions that are made using the conservation equations. The aim of this paper is to analyse the random nature of the field parameters in the reservoirs. An example is given which investigates the random nature of one of the parameters, permeability or the effective permeability, obtained from the pressure draw-down tests.
Prolog - A Computerized Wellsite Log Analysis System
Authors: Frost E. , Fertl W. H. , Wichmann P. A.
Published: December 2007

The Prolog computerized wellsite log analysis is designed to enhance the information obtained from Dresser Atlas Computerized Logging Service (CLS) Units.

Two basic analysis packages, Wellsite CRA for complex reservoir analysis and Wellsite SAND for clastic sediment sequences, present detailed formation evaluation in a four-track format supported by depth shift routines, a true vertical depth option, data edit routines including borehole and environmental log corrections, and crossplot routines.

The Prolog programs along with field examples are discussed.
Kick-off Problems in Central Oman (Haushi Producers)
Authors: Antheunis D.
Published: December 2007

In the Middle East few oil fields produce from accumulations in siliciclastic sediments. It was, therefore, considered useful to review some aspects of operating problems experienced in Oman with wells completed on such type of reservoirs.

The majority of wells in Central Oman producing from Haushi sandstone reservoirs have high skin factors as a result of –drilling and–workover fluids and/or–bridged formation fines in the vicinity of the wellbore.

The wells thus produce at reduced deliverability causing quitting and kick-off problems, early requirements for gas lifting and in the longer term possible problems in maintaining offtake levels. One of the current operations activities is, therefore, directed towards the resolution of kick-off problems.

This paper concentrates on the kick-off problems as experienced in the Central Oman area during the last two years.

The first class of kick-off problems showed up after workovers. The second category appeared after the quitting of a number of flowing wells, most of which were producing below ideal PI and with increasing watercuts.

Obviously, at fields where gaslift facilities are available, i.e. at all producing Central Oman fields except at Saih Rawl, the utilisation of gaslifting is straightforward and relatively easy and has of course been applied. In addition to gaslift assistance for kick-off purposes use was made of fluid lifting techniques, coiled tubings and swabbing and an in-situ nitrogen generation process was tested in oil well Ghaba North-2.

In this context of kick-off methods, the results of a field test of PDO's modification of the Navi-drill down-hole mud motor, with a view to flow wells to surface during drill-stem tests, is also reported.
Optimization of LPG and LNG Production from a Middle East Crude Oil
Authors: Al-Ameeri Rasheed S.
Published: December 2007

A computer simulator was designed to optimize the operating conditions of gas-oil processing systems. The separator off gases were utilized in the production of liquified petroleum gas (LPG) and liquified natural gas (LNG) and other byproducts. The mathematical model developed took into consideration all the variables affecting the operating conditions and a parametric study was conducted to determine the effect of the various variables on the final results, optimal solutions were found for systems processing crude oils of varying API gravity, feed temperature and pressure. Gas-oil processing systems consisting of different number of stages were analysed. The results indicated that as the number of stages decreased and as the specific gravity of the well fluid decreased the objective function became more sensitive to the operating conditions.
Injection Water Problems Identified by Laboratory Analysis
Authors: Ostroff A. G.
Published: December 2007

When water is injected into a subsurface formation, one or more operational difficulties may be encountered. A few examples of these are corrosion, scale formation, microbiological activity, formation of deposits, pollution considerations and rock property characteristics. Information necessary to defining these problems and mitigating them is usually obtained from a laboratory, A laboratory can provide the necessary information in a form pertinent to overcoming these problems or it can return information of questionable value in solving the problem. A cooperative effort between the engineer responsible for operation of the system and the laboratory offers the best chance for successful problem solving. Examples of some production related problems that illustrate involvement of the laboratory with the field engineer to find a solution are given.
Sucker Rods Failure Mechanisms, Methods of Avoiding them
Authors: Aly Eid Nabil Mohamed
Published: December 2007

When a steel bridge collapses, criticism is confined to the person responsible for the design-never to the mill that rolled the steel. This is true and justified because steel as turned out by modern mills is of closely controlled quality. It is one of our most exacting engineering materials whose mechanical properties are reproducible within close limits.

Conversely, when a String of sucker rods fails, the comment most frequently heard is that "they must have been rolled from a bad heat of steel". This is not justified nor logical since sucker rod steel is rolled under far more restrictive requirements than is ordinary structural steel. Practically all rod failures are the result of misapplication, mishandling, or are service induced. Failures due to faulty steel are so rare as to be practically nonexistent.

Finally, a reasonable understanding of well conditions and rod stresses leading to good string design, a knowledge of the causes of sucker-rod failures and the corrective practices required, and an updated selection of materials based on the most recent developments can pay big dividends in longer sucker-rod life.

Expensive down time, lost production, and. unnecessary maintenance costs are the usual results of bad-practice shortucts in handling sucker rods. A knowledge of the nature of sucker-rod failures, and causes leading to them, will show the reasons for using good practice and the false economy of using bad practice.

This article reviews sucker-rod failure mechanisms and suggests ways of avoiding them. Particular attention is paid to handling, running, pulling practices, material selection, and recent improvements.
Control and Repair of Offshore Well after its Wellhead Damage
Authors: Abdel-Mota'al Ahmed A.
Published: December 2007

This paper presents the operations conducted by an operating company in the Arabian Gulf, to put under control a gas well which its wellhead platform was accidentally damaged. Also, the conclusions are given which reflects the experience gained from the plans preparation for the well control operations and the results obtained during the implementation of these plans.
Effects of Production Rate on the in Situ Energy Utilization of Dry and Condensate Gas Reservoirs
Authors: Sarathi Partha S. , Tiab Djebbar
Published: December 2007

The objective of this study is to investigate the effect of production rate upon the utilization of primary reservoir energy. To achieve the above objective the problem was approached from the thermodynamic angle. In this investigation the first and second laws of thermodynamics together with the steady state flow principles were utilized to derive interpretive equations to calculate a thermodynamic value, namely the reversible maximum work function. The choice of the maximum work function as a working tool for analyzing the "response of a gas reservoir system to production practices" is justified by the fact that maximum work is independent of the path followed and hence can be utilized to establish production efficiency standards.

Three cases were studied in detail: (1) a volumetric dry gas reservoir system; (2) a dry gas reservoir system under water drive influence and (3) a volumetric gas condensate reservoir. Material balance relationships were used to simulate the reservoir pressure production history. The variation of well pressure with production is then systematically employed to compute the reversible work and to analyze the effect of production rate on the in situ reservoir energy utilization.

The volumetric and thermodynamic properties of the hydrocarbon mixtures were predicted using the modified BWR equation of state of Lee and Kesler. Hydrocarbon phase behavior is predicted using the concept of fugacity. Methods for computing the parameters to account for the interaction between the molecules of the mixture are also discussed. Techniques for predicting the reservoir pressure in these thermodynamic systems are developed.

The pressure prediction techniques and the thermodynamic property evaluation procedures are incorporated into a straight forward simulation scheme. Example cases studied indicated that the dry gas and condensated reservoirs are rate insensitive, while a reservoir subject to water drive is rate sensitive. for such reservoirs the natural energy is better utilized at lower production rate than at higher rate.
Viscosity Correlations for Compositional Reservoir Simulators
Authors: Saeedi Jawais , Rowe Allen M.
Published: December 2007

Compositional dependence of viscosities of reservoir fluids, where in-situ inter-phase mass transfer dominates, warrants judicious selection of correlations to be used in compositional reservoir simulators. Two of the selection criteria are that the vapor and liquid phase viscosities approach each other in the vicinity of the critical point and they should be well behaved functions of pressure, temperature and composition. As vapor and liquid phase viscosity correlations are usually developed independent of each other these criteria are not often met for most of the reservoir fluids encountered. Some of the viscosity correlations are phase density dependent which further require a consistent set of vapor and liquid phase density correlations or a reliable equation of state to predict both the phase densities.

Five sets of critical composition data are chosen for analysis. The choice is such so as to encompass reservoirs which may be candidates for compositional simulation and is also based on the mo lal average boiling points of the mixture. Each of these critical compositions are flashed along the critical isotherm at suitable pressure intervals, upto the critical point. Densities and viscosities are then computed for liquid and vapor phases at each pressure level using suitable correlations.

Specific correlations are recommended for usage in phase viscosity computation, for each composition used in this study, supplementing the necessity of fine-tuning their parameters for specific reservoir fluids from laboratory derived fluid data. The suitability of phase density correlations, to be used in conjunction with viscosity correlations, is also discussed.
The Use of Foamed Acid in Fracture Acidizing
Authors: Ford William G. F.
Published: December 2007

Dynamic laboratory testing of foamed acid on limestone cores has established the effectiveness of foamed acid as a stimulation fluid. Effects of foam quality, foam stability, and chemical compatibility on fluid loss and fracture flow capacity were investigated. Recommendations are presented for deriving maximum benefits from a foamed acid treatment. Field results are presented that show the effectiveness of foamed acid in fracture acidizing treatments of both oil and gas wel1s.
Application of Computer Data Base Techniques for Reservoir Management
Authors: Smith Michael D. , Lucas Charles D.
Published: December 2007

An engineering work station is described which includes a mini-computer, an interactive colorgraphics terminal and a four color pen plotter integrated with a well data base and reservoir performance models. This combination of technical models and data management software is a powerful tool for predicting reservoir performance and ultimate recovery of reserves. In addition, to increase the efficiency and effectiveness of technical personnel, the work station substantially reduces the amount of time required for these personnel to collect, store, retrieve and process production and engineering data.
Screening Tests for Enhanced Oil Recovery Projects
Authors: Burnett David B. , Dann Michael W.
Published: December 2007

Laboratory Screening Tests are suggested to evaluate potential enhanced oil recovery projects. Standardized procedures are used to study the feasibility of (1) miscible/CO2 projects, (2) thermal processes, and (3) chemical processes.

The Screening Tests are divided into four sections: crude oil characterization, injection water studies, reservoir core characterization, and displacement studies in porous media.

These Screening Tests augment geologic and engineering studies and supplement (but do not replace) the more commonly known core analysis programs.