bluuebunny/crossref_metadata_2025 huggingface dataset:
Short-Radius Lateral Drilling: A Completion Alternative
Authors: Parsons R. S. , Fincher R. W.
Published: December 2007

The drilling of horizontal holes from a vertical wellbore to enhance oil and gas production has become a renewed topic in well completion technology. A concept over 50 years old, lateral drilling was originally thought of as a cure for declining or marginally productive wells. Today, because of improved materials, designs, and manufacturing techniques, lateral drilling has emerged as a promising completion technique in many types of reservoirs.

This presentation will discuss state-of-the-art, short-radius lateral completion technology, specifically the method offered by Eastman Christensen. A Michigan case history will also be discussed in which the technique was used to turn a well destined for abandonment into a commercial success.
Flow of Non-Newtonian Fluid in Porous Media
Authors: Abou-Kassem J. H. , Farouq Ali S. M.
Published: December 2007

A mathematical description of non-Newtonian fluids, in particular, emulsions, is of special importance now that most of the enhanced oil recovery methods are being modeled in increasing detail. Only recently a few characteristics of emulsion flow have been incorporated in some of the simulators. Nearly all enhanced oil recovery processes involve emulsion formation and flow in some form or other. Representation of such flow in mathematical models is still inadequate.

This paper investigates the rheology of emulsions, their formation in porous media, and subsequent flow, from a mathematical standpoint. A critical evaluation of several models describing the flow of pseudoplastic fluids in porous media is presented. The models are expressed in a unified form that makes it possible to detect differences between the various models. The assumptions underlying the various models are discussed in detail. Furthermore, the paper gives a summary of the rheology and in situ formation of emulsions, and the role of a variety of other factors responsible for emulsification in porous media.

The paper concludes with suggestions for incorporating emulsion flow in reservoir simulators. Extension to non-isothermal conditions is also discussed.
Simulation of Laboratory In-Situ Combustion Data and Effect of Process Variations
Authors: Kumar M.
Published: December 2007

A fully implicit thermal simulator was validated by history matching laboratory combustion tube data. The validated simulator was used to identify important parameters that influence the predicted results and to study the effects of process variations. Measured cracking reaction parameters were used to minimize the number of adjustable parameters in history matching.

Results indicate that the simulator can history match the laboratory data when the relative permeabilities are modified. Matched experimental parameters include cumulative oil and water production histories, location of combustion front as a function of time, and peak temperatures along the tube. The simulation results were insensitive to the kinetics of combustion, grid size, sand thermal conductivity, and equilibrium coefficient of the heavy oil pseudocomponent. The results, however, were sensitive to relative permeability, capillary pressure near the irreducible water saturation, and equilibrium coefficient of the light oil component.

Predicted trends for oxygen injection, wet combustion, and variation in injection rates agree very well with published experimental results. Injection of oxygen instead of air (for nearly the same combustion front velocity) caused a significant increase in the fuel consumption and peak temperatures. Wet combustion generally caused a decrease in the fuel consumption and the average peak temperature, and an increase in the combustion front advance and production rates. The velocity of the combustion front was proportional to the air flux at the combustion front, except at very high injection rates. This implies that at field-like injection rates, the combustion process is air (oxygen) flow rate controlled.
Borehole Instability: Case Histories, Rock Mechanics Approach, and Results
Authors: Maury V. M. , Sauzay J-M.
Published: December 2007

In order to find a solution or at least to minimize the consequences of borehole instability, two complementary approaches of the problem have been used:

– Case history analysis: identify from the different types of drilling problems those related to a poor borehole behavior, characterize the conditions for occurrence and main consequences (breakouts, cavings, reaming, torque) in agreement with a proper geomechanical behavior of the borehole. Several independent, or interconnected factors are controlling the borehole stability: high or low, isotropic or anisotropic horizontal stresses, particular rock rheological behavior, excessive wall stresses induced by fast tripping, pressure and temperature gradient around the borehole. – A comprehensive theoretical analysis providing a stress distribution around the borehole, avoiding irrelevant material behavior, and concentrating on the different loadings which may already explain most of the time-delayed instabilities (thermal and seepage stresses). Some major and unusual conclusions will be outlined: several rupture modes, maximum stress concentration inside the wall.

Two documented case histories are described. They allow to be rather optimistic regarding the efficiency of this mixed approach of the problem in providing less empirical solutions to drilling problems.
Guidelines for Stable Foam Drilling Through Permafrost
Authors: Fraser I. M. , Moore R. H.
Published: December 2007

Stable foam was used successfully on ten wells in the Canadian Arctic to drill near gauge holes through permafrost. During the program, important practical information on foam drilling guidelines and operational considerations were obtained. The results indicate that the optimum foam quality for ensuring good hole cleaning varies with drilled depth and lithology. The data is presented in a graphical format which can be applied directly in the field.
Zistersdorf ÜT2A: Milling 867 ft of a 75/8-in.×56-lbm Q 125 Liner
Authors: Baldauf F. , Vock W.
Published: December 2007

OEMV milled 867 ft (264.5 m) of 7 5/8″ × 56 # Q 125 liner to obtain good conditions for a sidetrack at 19 816 ft. The different types and designs of milling tools were subjected to a pilot test. A scale to scale model of the casing combination was submerged and anchored inside the conductor pipe of another well. The best results during the milling operation at a depth from 19 023 to 19 890 ft were achieved with tungsten carbide cutting elements with a diameter of 1/2″ and with a rhombic design.
Soil Farming of Oil Mud Drill Cuttings
Authors: Whitfill D. L. , Boyd P. A.
Published: December 2007

In 1980 Conoco recognized the need for proper disposal of oil mud cuttings and has conducted both controlled "pilot-scale" soil farm studies and full scale field studies. Both the pilot scale and full scale studies show rapid reduction of hydrocarbons for both diesel oil and mineral oil base muds—up to 90 percent oil reduction within one year.

In addition to demonstrating the rapid reduction of oil, these studies also show the immobility of both hydrocarbons and heavy metals in the soil. The comparison of concentrations in the upper 1 foot of soil with those below 1 foot shows no increase in concentration of either hydrocarbons or metals by downward leaching.

These tests also show no preferential leaching of hydrocarbon species, with the relative fraction of both paraffins and aromatics decreasing with time and depth of sampling. Other studies of land farming processes have established a 5 weight percent oil-in-soil treatment level as being environmentally safe.

In summary, the soil farming of oil mud cuttings and drilling wastes is a viable and environmentally sound means of disposal.
The Causes of Shallow Gas Kicks
Authors: Goins W. C. , Abies G. L.
Published: December 2007

Shallow gas blowouts have occurred worldwide. Short casing strings and low fracture gradients prohibit holding back-pressure, and wells can only be diverted. Under these conditions well control procedures are much less certain, and risk of cratering and loss of well is high. This places a great emphasis on kick prevention.

Well control schools tend to focus on deeper drilling and the peculiarities of shallow gas are not thoroughly addressed.

Due to the low margin of overbalance that exists on shallow sands, a small loss of hydrostatic pressure, easily tolerated in deeper drilling, can initiate flow into the wellbore. These conditions are illustrated and related to loss of circulation and hole filling during trips.

Drilling shallow gas sands too fast is examined as a potential mechanism for causing blowouts. Previous work in this area has shown that gas cut mud will seldom cause a blowout from the formation being drilled. While this is generally true, gas cut mud can lower the hydrostatic pressure enough to allow shallower formations to flow. A more comprehensive equation than heretofore published is developed, and several drilling parameters are examined to show their effects on the effective mud density at depths above the interval being drilled. A significant conclusion is that a sand might be drilled safely if casing is set just above the sand, but the same drilling conditions could cause an uncased, shallower sand to blow out.

The paper also shows that shallow gas sands which are normally pressured at the bottom of the gas interval can require higher mud weights to control formation pressures at the top of the gas interval. This is due to the difference between the gas gradient in the formation and normal formation gradient.
The 1987 IADC Fixed Cutter Bit Classification System
Authors: Winters W. J. , Doiron H. H.
Published: December 2007

The International Association of Drilling Contractors (IADC) has adopted a new method for classifying fixed cutter (diamond) drill bits according to their design features. Seven design traits are described by a four-character code. The code applies equally well to drill bits and core bits with natural diamond, polycrystalline diamond compact (PDC), thermally stable polycrystalline (TSP) diamond, or any other type of fixed cutter elements.

Examples of typical fixed cutter bit designs are shown along with the appropriate IADC classification code.

Improvements in fixed cutter bit utilization are expected through use of the new IADC classification code in conjunction with the first ever IADC dull grading standard for fixed cutter bits.
Application of the New IADC Dull Grading System for Fixed Cutter Bits
Authors: Clark D. A. , Coolidge R. B. , Kelety J. T. , Kerr J.
Published: December 2007

This paper describes a recently developed standardized system for dull grading natural diamond, PDC, and TSP (Thermally Stable Polycrystalline diamond) bits, otherwise known as fixed cutter bits. The new system is consistent with the recently revised dull grading system for roller bits. It describes the condition of the cutting structure, the primary (with location) and secondary dull characteristics, the gauge condition, and the reason the bit was pulled. Examples of all commonly seen dull characteristics of fixed cutter bits are given. In addition, several worn fixed cutter bits are dull graded using the system.
Application of the 1987 Roller Bit Dull Grading System
Authors: Hampton S. D. , Garris S. , Winters W. J.
Published: December 2007

The IADC has adopted an improved rock bit dull grading system modeled after the previously used "T,B,G Remarks" approach. This paper discusses the improved system as it applies to roller cone bits (application of the new system for fixed cutter bits is presented in another paper). A complete definition of the system is given. Descriptions and possible causes of many dulling characteristics of roller cone bits are presented and briefly discussed. Some example dull bits are graded using the improved system. An application of the dull grading system as used in well planning is demonstrated.
Case History of Lowering Cost in Mature Field through Optimization Efforts
Authors: Brennan R. M.
Published: December 2007

Drilling and completion operations in mature fields have a long history of optimization efforts targeted towards performance improvements and minimum operational cost. While older fields are not typically regarded as prime candidates for major cost reductions, cost performance is essential for all areas in a time of declining oil prices. Exxon Company U.S.A recently established several cost reduction study teams to review mature field drilling and completion programs. Cost reduction without compromising overall objectives or jeopardizing operational safety was the goal of these study teams. Summarized herein is the methodology incorporated in one of the fields studied and the resulting twenty-two percent reduction in drilling and completion costs.
MWD Performance and Economic Benefits in the Zu Horizontal Drilling Program
Authors: Clary M. M. , Stafford T. W.
Published: December 2007

This paper describes the application of Measurement-While-Drilling (MWD) technology as used in a Horizontal Drainhole Drilling Program. The requirements of both formation evaluation and directional survey measurements while drilling will be discussed with reference to field results obtained. The ability of the MWD tool to make formation evaluation measurements, in order to identify casing seats and formation tops will be shown as essential to the project. The field examples described in this paper are from results obtained as part of the Atlantic Richfield Indonesia Inc. (ARII), 1986 ZU Field Development Drilling Program. The economic benefits of the utilization of MWD by ARII will be included.

MWD proved to be ideally suited to the directional drilling of high angle wells, and horizontal wells in particular. The placement of horizontal completions was critical, and very little deviation from the proposed well plan could be tolerated. Lithologic interpretation was critical to prevent drilling out of the top or bottom of the pay zone and MWD was sufficiently reliable to track the horizontal section of the wellbore. Wireline logs were eventually eliminated on later operations. The overall economic benefits of MWD were derived by comparing surveying costs and drilling time costs between similar wells drilled and surveyed conventionally versus those drilled using MWD.
An Experimental Investigation of the Performance of a 3-in. Hydrocyclone
Authors: Young G. A.
Published: December 2007

A special 3 in. hydrocyclone with interchangeable pieces, which allowed all the dimensional parameters to be varied, was built. A two7 factorial test was run that identified which hydrocyclone parameters are most important with respect to flow rate and performance. A total of 450 tests of hydrocyclone performance have been conducted using one drilling mud. Based on these tests, a mathematical regression model was written which parameterizes the data for the test mud. The results of this model is presented graphically. These tests have shown that there is an optimum set of hydrocyclone dimensions which provide maximum separation. For the test mud, the performance of an optimum hydrocyclone is at least 25% greater than desilters presently utilized in the oilfield today. Dimensions for a hydrocyclone with near optimum separation which have a flow rate of 50 gpm are also presented. Utilization of optimum hydrocyclones will result in significant savings due to increased penetration rates and lower mud costs.
Financing of Oil and Gas Transactions
Authors: Bergen Richard C.
Published: December 2007

This paper considers the different ways of financing oil and gas transactions and points out that the financing method selected could be responsible for any given deal being much better, or worse, than anticipated by the engineers. In the drilling of wildcat prospects, for instance, the carried interest or the free-well type of contractual agreement could have entirely different consequences depending upon the particular form taken by the agreement. Also, when a proven well is financed by the carving out of an oil payment, a very substantial difference results if the oil payment is pledged to the development of the property. Financing of the purchase of producing properties by the so-called ABC procedure could result in the purchase price of a property being largely paid for by the proceeds from production without diminution due to income taxes.

Introduction

The function of this paper is to discuss the various possible methods of investing in or borrowing upon oil and gas properties, pointing out the advantages and disadvantages of using one method rather than another. The particular method selected can, and does under our tax laws, make a tremendous difference in the economics of the venture. For instance, if one method would result in the imposition of a Federal income tax on the production in question at the maximum corporate rate of 52 per cent and if another method would substantially avoid the imposition of this tax, it is evident that the method which would avoid the tax could make the venture twice as attractive as would otherwise be the case. As will be seen later, this is not simply a theoretical possibility; accordingly, tax planning in the oil and gas field leaves plenty of room for an inventive tax attorney.
Diverting Agents: Laboratory Study and Modeling of Resultant Zone Injectivities
Authors: Doerler N. , Prouvost L. P.
Published: December 2007

A methodology for the design of the diversion stages of matrix acidizing jobs is presented. The resistance to flow induced by a cake of diverting agent deposited at the sandface of a single core has been measured in the lab under a large variety of conditions, representative of those encountered downhole.

The experimental data are then combined with a numerical model to yield a design tool for diversion jobs, which enables to predict the flow distribution due to diverters in multi-layered formations, according to both reservoir and diverter properties.

Finally, results obtained with the model are presented, to demonstrate how it can be used to optimize the volume of diverter slugs in matrix acidizing treatments.
Alumina Precipitation in Porous Media for Profile Control
Authors: Torrest R. S. , Huang S-H.
Published: December 2007

The precipitation of hydrated aluminum oxide from aqueous solutions can be controlled with reactions that change solution pH. Gels, fine grained precipitates and tightly adhering coatings can be readily produced within porous media to provide profile control. Substantial permeability reductions to over 99% were achieved with small amounts of gels not only in a 5 darcy sand, but also in relatively coarse 20/40 mesh glass beads and gravel. Laboratory results show the influence of injection volume and rate on overall permeability reduction. Profiles for permeability and gel content were also measured. Gel size distributions from static and plugging experiments show the development of sizes leading to effective control.
Optimization of Vertical Acid Fractures in Steady-State Flow
Authors: Sevougian S. D. , Schechter R. S. , Sepehrnoori K.
Published: December 2007

The first step in the formulation of acid-fracturing fluids is to specify an optimal range for each of the fluid properties. To do this, a new procedure is developed for the optimization of hydraulic acid-fracturing treatments. This procedure first predicts the optimum fracture geometry, namely, the geometry which maximizes the stimulation (or productivity) ratio for a given acid volume and then identifies the fracture fluid properties needed to create this geometry.

By utilizing the calculus of variations, an analytical solution is found for the optimum fracture geometry. This solution has several important features. First, the optimum dimensionless fracture shape (conductivity profile or acid-spending profile) in undamaged reservoirs is invariant with respect to both acid volume and formation properties; and, furthermore, this shape is nearly uniform (i.e., constant conductivity) over the entire length of the fracture. Second, the optimum length is a function of a single dimensionless variable. Third, the optimum shape (acid-spending profile) in damaged reservoirs is nearly the same as in undamaged reservoirs and essentially independent of the extent of damage, so long as the fracture extends beyond the damaged zone.

By combining the variational solution for optimum fracture geometry with existing analytical models of the acid reaction and fracture growth processes, it is possible to define ranges of fluid properties which will yield a treatment closely approximating the optimum one. The primary conclusions reached by this method are that the Peclet number for viscoεified acids must be large, approximately 4.0, to achieve the optimal shape; and that optimal fluid-loss coefficients are greater than those previously thought desirable. In fact, it appears that fluid loss except in highly fissured or vuggy carbonate formations is not a critical design variable. Furthermore, very low injection rates or relatively high diffusion coefficients may require unacceptably high acid viscosities.
High-Temperature/High-Pressure Solubility Measurements in the Systems BaSO4-NaCl-H2O and SrSO4-NaCl-H2O in Connection With Scale Studies
Authors: Schulien S.
Published: December 2007

Solubility data on BaSO4 and SrSO4 have been determined in the temperature range 353 to 393 K at pressures up to 41,4 MPa (6000 psi) and at ionic strength of NaCl brines between 0.1 and 2.0 M. The experiments were performed in a high temperature/high pressure test equipment by applying the dissolution technique. The experimental results confirm the general trend in solubility dependencies for both BaSO4 and SrSO4, determined at lower temperatures and pressures: pronounced increase in solubilities of BaSO4 and SrSO4 with increasing ionic strength, slight increase in solubilities when pressurizing the solutions up to 41.4 MPa. A temperature rise from 353 to 393 K causes an increase in BaSO4 solubility, but a decrease in SrSO4 solubility. Calculation of the solubility products reveals for BaSO4 an increase from 1.1 • 10−10 in pure water at 298 K and normal pressure to 5.1 • 10−8 in 2M NaCl brines at 393K and 41.4 MPa. For SrSO4 the solubility product increases from 2.8 • 10−7 in pure water at 298 and normal pressure to 18.2 • 10−7 at 373 K and 41.4 MPa and to 16 • 10−7 at 393 K and 41.4 MPa in 2M NaCl brines.
Development and Evaluation of EOR Polymers Suitable for Hostile Environments: II—Copolymers of Acrylamide and Sodium AMPS
Authors: Moradi-Araghi A. , Cleveland D. H. , Westerman I. J.
Published: December 2007

Copolymers of acrylamide (Am) and sodium-2-acrylamido-2-methylpropane sulfonate (NaAMPS) have been evaluated for flooding applications at elevated temperatures. The brines employed in this study include synthetic seawater (447 ppm Ca++, 1256 ppm Mg++ and 33,560 ppm TDS) and others containing a It 10 weight ratio of CaCl2 to NaCl and having TDS ranging from 0.55 to 16.5%. AMPS is a registered trade mark of the Lubrizol Corporation.

While NaAMPS homopolymer solutions are thermally stable at 121°C (250°F), and hydrolyze very slowly and to about 4% after extended aging, copolymerization of NaAMPS with acrylamide does not appear to protect the later against thermal hydrolysis and consequent precipitation in hard brines. Only Am-NaAMPS copolymers containing less than 9 wt.% Am might tolerate a brine such as seawater at 121°C (250°F). Comparison of these results with those reported for vinylpyrrolidone (Vp) and acrylamide copolymers which showed stability for a copolymer containing 50 wt.% Am in seawater at 121°C (250°F) is evidence that Vp protects acrylamide against thermal hydrolysis, but NaAMPS does not.

Evaluation of various weight ratios of Am-NaAMPS copolymers for flooding applications at 93°C (200°F) resulted in an optimum composition near 40/60 wt. ratio of Am/NaAMPS. Given the fact that polyacrylamides are suitable for flooding applications up to 75°C (167°F), inclusion of about 60 wt.% of a more expensive NaAMPS monomer into the copolymer composition to increase its usability limit by less than 20°C (36°F), does not appear economically viable. It is believed that many of the so called "high temperature" polymers commercially available, are NaAMPS based materials containing high levels of acrylamide and are not suitable for polymerflooding at temperatures significantly higher than those of polyacrylamide.
Dissolution Rates for Quartz, Aluminum-Bearing Minerals, and Their Mixtures in Sodium and Potassium Hydroxide
Authors: Diallo M. S. , Jenkins-Smith N. L. , Bunge A. L.
Published: December 2007

High pH dissolution of quartz, aluminum-bearing minerals and their mixtures is important in several oil production processes. Rock consumption of caustic is a major limiting factor for successful alkaline waterf looding. Chemical dissolution of the gravel pack and near well-bore rock are problems in both steam and caustic flooding. Mineral dissolution is probably a contributing mechanism for the reported success of potassium hydroxide treatments in effectively and permanently stabilizing clays.

The presence of even small amounts of soluble aluminum can greatly reduce the kinetics of silica dissolution in near neutral and high pH solutions. Earlier research has shown that clay minerals frequently dissolve more slowly than quartz or amorphous silica. Although these clay minerals may not themselves contribute substantially to caustic consumption, they release aluminum ions which may slow dissolution rates of other silaceous minerals.

Most previous dissolution experiments have examined dissolution of single minerals. In this paper we report experimental dissolution results for quartz, kaolinite, and α-alumina and their binary mixtures in 0.1 N NaOH solutions at 70°C. Results for quartz and kaolinite in 0.1 N KOH are also described.

When soluble aluminum or aluminum-bearing minerals are present, the dissolution rate of quartz is significantly reduced. Adding soluble silica can have a similar affect on kaolinite dissolution rates as measured by production of aluminum and silicon. In-congruent dissolution occurred when kaolinite solutions were shaken.
Foaming Agents for EOR: Correlation of Surfactant Performance Properties with Chemical Structure
Authors: Borchardt J. K.
Published: December 2007

Foams have been proposed for use as mobility control agents and to improve conformance in various EOR processes. Multiple correlation analysis has been used to generate equations relating foam data to the chemical structure of alcohol ethoxylates and alcohol ethoxylate derivatives being considered for use as CO2 "foaming" agents. Important surfactant structure parameters determining foaming performance include molecular weight, mole percent ethylene oxide, and hydrophobe carbon number and chemical structure.

Steam foaming agents have also been studied using multiple correlation analysis. Mobility reduction factors (MRF) observed when an alpha-olefin sulfonate (AOS) and 200°C steam were injected into sand packs could be correlated with AOS concentration and the gas:liquid volume ratio. Branching at the 2-position of AOS surfactants reduced the MRF substantially. This reduction appeared to be related primarily to inductive effects of the side chain.

Other surfactant properties of importance in enhanced oil recovery include critical micelle concentration, cloud point, interfacial tension, and adsorption. These properties have been related to surfactant structure using multiple correlation analysis.
Effectiveness of H2S Scavenging by Ironite Sponge at High pH
Authors: Wendt R. P.
Published: December 2007

This paper examines the discrepancy between good field results with Ironite Sponge® in alkaline drilling muds, and the low rates of reaction between Ironite Sponge® and H2S predicted by a previously published rate law for the reaction. Two explanations are proposed, based on further laboratory studies at high pH: (1) An intrusion-reaction effect, where the pH is significantly lowered during intrusion of H2S, allowing the reaction to proceed rapidly before the pH again rises due to consumption of H2S. This effect can result in removal of 40 percent or more of initial sulfides even for highly buffered alkaline muds. (2) Ironite Sponge® catalyzes the reaction between dissolved oxygen and H2S at high pH. In the mud pits at a drilling site this effect can account for rapid removal of residual sulfides in circulated drilling fluids. Both effects, together with the instantaneous rate law, can account for low sulfide levels and absence of drill pipe failures reported by other authors for alkaline Ironite Sponge® slurries used with sour gas systems.
Worldwide Oil and Gas Supply and Demand
Authors: Osman M. E.
Published: December 2007

This paper reviews oil and gas worldwide supply and demand and their effect on oil prices and consequently on related industries such as refining, drilling technology, enhanced oil recovery, natural gas liquefaction,..etc. The proved oil reserves in the world is about 7×1011 bbl with about 56% located in the Middle East. The worldwide natural gas reserves is estimated as 3.484×1015 ft3 with 43% located in U.S.S.R and 25% in the Middle-East. The heavy oil reserves is estimated as 5.8 – 5.9×1012 barrels with 72% located in Venezuela. The bitumen reserves is estimated as 200 billion barrels with 82% located in Canada.

In 1979, oil production reached it's peak of about 66×106 bbl/day out of which 21.91×106 bbl/day was produced from the Middle East. Then the demand for oil declined till 1985. An increase in the demand was reported in early 1986. About 25% of oil produced was consumed by U.S.A., 21% by Western Europe, 15% by U.S.S.R. and 7.5% by Japan. Oil tankers, especially supertanker, and refining industries were suffering in the last several years as they were operated at rates less than their capacities. Oil prices declined since 1982 and collapsed in 1986. Such reduction in oil price, if sustained, is expected to hurt drilling activities, enhanced oil recovery projects which may result in less supply and declining reserve and consequently a big hike in oil prices in the future. Among different sources of energy, oil has proved to be the main source of energy for worldwide consumption.

The demand for gas is increasing. The production in early 1986 reached a rate of 190×109ft3/day with about 35% produced from U.S.S.R and about 25% from U.S.A. The main consumers of natural gas are U.S.S.R., U.S.A., Japan and Western Europe. U.S.S.R. supplies Western and Eastern Europe with most of their needs of natural gases.
The Error in Estimating Reserves Using Decline Curves
Authors: Thompson R. S. , Wright J. D. , Digert S. A.
Published: December 2007

A common method of estimating remaining reserves is decline curve analysis. There is a tendency to believe that estimates of remaining reserves will improve (become closer to truth) as more production data becomes available. This is not necessarily true even though our estimate of the ultimate recovery will generally improve with increased production history. The use of curve fitting techniques will not necessarily increase the accuracy of estimating remaining reserves and may, in some cases, lead to unreasonable answers. Reserve estimates will also vary among reserve estimators using the same data. This variance can be significant as demonstrated by the results of a controlled experiment presented in this paper.
Leveraged Buyouts and the Petroleum Industry
Authors: Paulus C. A.
Published: December 2007

The characteristics of the typical exploration and production company do not match that of an ideal leveraged buyout candidate. This paper discusses the reasons to undertake an LBO, describes the traits of an ideal LBO candidate and compares them to the typical petroleum industry firm.
Effective Evaluation of Loans To Reduce Risk
Authors: McPhail W. R.
Published: December 2007

The risk associated with borrowing money secured by oil and gas properties in an environment of rapidly fluctuating oil prices can be reduced by understanding the energy lending process and systematically comparing the loans offered by various banks. Furthermore, by viewing an existing loan which is in default from the bank's viewpoint, the borrower may be able to be more successful in avoiding foreclosure.
FDIC Energy Asset Marketing
Authors: Cook L. P.
Published: December 2007

Through circumstances, definitely not by choice, FDIC has become a major player in the oil and gas business. At year end we had approximately $2.3 billion dol1ars book value of Energy loans and owned assets under liquidation nationwide. Energy assets are approximately 35% of our total assets in liquidation, a major investment and one we would like to reduce. The purpose of my presentation today is to provide you with the information necessary to purchase our Energy assets or any other FDIC asset you may be interested in.

I represent the Division of Liquidation of FDIC. As the name implies, we are responsible for converting the Corporation's assets into cash. Specifically, our stated mission is to "…Achieve the highest possible level of collection on assets at the earliest practical time in the most cost efficient manner. In doing so, it seeks to maximize the return of funds to the FDIC as well as other conditions of the failed banks."

One of our primary vehicles to convert to cash is our Asset Marketing Program. We are very active nationwide in selling loans, owned assets, and portfolios of assets to investors on a private treaty, sealed bid, and public auction basis.
The Only Investment Selection Criterion You Will Ever Need
Authors: Seba R. D.
Published: December 2007

The investment evaluation process is comprised of two components, namely screening and ranking of investment opportunities. Screening identifies those projects which meet or exceed a predetermined standard, whereas ranking places those projects in order of most desirable to least desirable. A screening criterion is necessary for every economic evaluation, to assure that only those investments will be made which will contribute to achieving the desired goals of the investing organization. Ranking criteria are only needed to allocate resources when they are in short supply. Selection of projects, from the investment opportunities being considered, in accordance with proper ranking criterion will yield the maximum return possible with the limited resources available.

This paper will discuss the ratio of net present value to present value investment, commonly referred to as present value ratio, present value index or percent present value profit. It will be shown that this index can be used both as a screening and a ranking criterion, if it is based upon the proper opportunity cost of capital. It will always properly rank investment opportunities, when investment funds are the resource in short supply, provided that the effect of delaying a project is included in the analysis. Use of this criteria over a great number of years has proved its value. By simple examples it will be shown that this criterion is easily calculated from information already determined for most economic evaluations and that it will properly rank all types of investment opportunities, while other criteria frequently used in the Petroleum Industry will not. It will be specifically shown that internal rate of return and growth rate of return can be misleading when used as ranking criteria because of their inherent bias in favor of near term cash flows.

Frequently, screening and ranking criteria are arbitrarily adjusted to compensate for ill defined and unquantified risk and uncertainty. This paper will discuss the proper procedure to account for risk and uncertainty in screening and ranking investment opportunities.
The Need for More Reliable Decision Criteria for Drilling Prospect Analyses
Authors: Newendorp P. D. , Quick A. N.
Published: December 2007

This article discusses the practice of using "risked reserves" as an input parameter to economic models used to analyze drilling prospects. "Risked reserves" are here defined as the probability-weighted average of the possible field sizes. We will show that, in general, using a single point "risked reserves" value in determining prospect viability will result in an erroneous and misleading decision parameter. Recommendations are given which will provide more reliable decision criteria.
Steam Injection Strategies for Thin, Bottomwater Reservoirs
Authors: Proctor M. L. , George A. E. , Farouq Ali S. M.
Published: December 2007

This paper presents the results of thirty-nine scaled model experiments which were conducted to study variations of steamflooding in thin, heavy oil formations, with bottom water present in many instances. The work primarily addresses Lloydminster, Saskatchewan, type reservoirs which are characterized by a viscous oil (1275 mPa·s at reservoir temperature) and a thin pay (6 − 13 meters). Reservoirs of this type are common in Saskatchewan and eastern Alberta; thus it is imperative to develop recovery strategies which are likely to succeed in the field, which was the objective of this research.

Experiments of many types were conducted, many of which gave favorable results. Eight of the thirty-nine experiments were conducted with bottom water models, using strategies based on steamflooding experience gained from the homogeneous model experiments. It was found that by injecting an inert gas into the model, prior to steamflooding, the effect of thick bottom water zones can be minimized. Temperature profiles indicate that the injected gas creates a flow channel away from the water zone, and that the injected steam tends to follow this path of least resistance, rather than channeling directly into the bottom water zone. Injecting gas into a bottom water model, prior to steamflooding improved the oil recovery from 16.79% to 20.66% of the original oil in place.

The experimental results suggest that there is some minimum bottom water thickness (approximately 10% of the gross pay thickness), below which the effect of bottom water is small.
Residual Gas Saturation in Water-Drive Gas Reservoirs
Authors: Firoozabadi A. , Olsen G. , van Golf-Racht T.
Published: December 2007

In water-drive gas reservoirs (even with an active aquifer), there is some pressure drop in the reservoir during the course of depletion. Until very recently, the literature assumes that the residual gas left in the water invaded region is constant which remains the same during the depletion process. In order to test the validity of the assumption of a constant value for residual gas saturation in the course of pressure drop in a water-drive gas reservoir, the following experiments were conducted.

Three different tests were performed in the vertical direction on each of the core samples. In the first test water was injected into a vertical core (saturated with methane and in some cases with irreducible water) from the lower end at a constant low rate. Water injection was conducted at a pressure of about 217.5 psia [1.500 MPa]. The injection of water was continued for several days. No additional gas was, however, produced once the water breakthrough occurred. The second test comprised the depletion of the core from the upper end at the termination of the water injection period. The depletion was realized by lowering the pressure and producing the fluids. In the third test, water was again injected at the lower end with the same rate as in the first test.

A simulation model of an implicit-type was used to analyze the laboratory data. The history matching of the depletion test revealed extreme sensitivity to the mobilized gas saturation value.

The laboratory measurements and the simulation results show clearly two distinct values of residual gas saturation. The lower value corresponds to the initial gas entrapment saturation and the higher value relates to the gas saturation being mobilized under expansion. For the cores examined in this research project, these saturation values are about 30 and 40 percent of pore volume, respectively.
The Effects of Lithology and Reservoir Pressure on the In-Situ Stresses in the Waskom (Travis Peak) Field
Authors: Whitehead W. S. , Hunt E. R. , Holditch S. A.
Published: December 2007

This paper presents an overall summary of the in-situ stress data obtained through the Gas Research Institute (GRI) Tight Gas Sands Research Program. Data of this type can be invaluable to anyone designing a hydraulic fracture treatment in a complex, multi-layered reservoir. Correlations are presented that allow the in-situ stress gradient to be calculated from openhole log data as a function of reservoir pressure.

Results from thirty-four (34) stress tests in five wells in the Travis Peak formation of east Texas are presented. Twenty of these tests were conducted as part of the 1986 GRI Staged Field Experiment in the Waskom (Travis Peak) Field in Harrison County, Texas. The primary purpose of these tests was to determine the in-situ stresses of the various lithologies in this multi-layered, complex reservoir. Knowledge of the vertical stress profile can help to make estimates of vertical fracture growth as a function of excess pressure in the fracture.

Formation pressures were obtained in many zones with either wireline formation testers or pressure buildup tests. These estimates of reservoir pressure were then correlated with the actual measured values of in-situ stress to determine the effects of pressure depletion on the in-situ stress. Calculated values of in-situ stress from logs were calibrated using the measured values of reservoir pressure and in-situ stress.
Optimizing Reservoir Surveillance by Using Streamlines and the Microcomputer
Authors: Flanders W. A. , Bates G. R.
Published: December 2007

Oil production over the last several decades has become more dependent upon secondary and tertiary recovery techniques. There have been significant advances in the use of reservoir modeling to help design and evaluate these processes. Unfortunately, there have not been similar advances made in the tools for reservoir surveillance. Injection costs can be the major factor contributing to the profit or loss of a project, therefore creating the need to maximize injection efficiency.

Combining streamlining techniques with the micro-computer can result in an invaluable reservoir surveillance aid. A streamline program can be used to generate an allocation matrix not only for each pattern but also for each fractional pattern. The allocation matrix can then be used with other programs to distribute the production and injection to each well and fractional pattern. Monitoring the project on a fractional pattern basis enables the reservoir surveillance engineer to promptly identify potential problems and to make modifications as necessary to maximize profitability. The injection-withdrawal ratio can be evaluated for each fractional pattern, for individual wells, or for the entire project. Injection requirements can be determined more precisely for each well to maximize utilization of the injectant and minimize costly recycling.

This paper reviews how a streamline model has been integrated with an allocation program on a micro-computer to maximize reservoir surveillance.
A Gas Field Development Model for Use on a Microcomputer
Authors: El-Feky S. A.
Published: December 2007

This paper presents a gas field development model that combines certain facets of previously published ones. The manner of combination has required the development and use of some new and some little-known relationships, permitted accurate future performance predictions, eliminated several of the simplifying assumptions that might introduce gross inaccuracies, and removed the necessity of referring to plotted curves. This model which was designed for microcomputer solution, permits the analytical prediction of a gas field to meet a gas sales contract length and rate, based on reservoir capacity, individual well and equipment capacity, and the state of depletion of the reservoir as predicted by material balance. Based on the model predictions, recommendations concerning drilling and completion schedule of additional infill wells and the need for compression facilities, to meet the gas sales contract, have been made.
Waterflood Performance Estimation With a Layered Streamtube Model
Authors: Cox D. O.
Published: December 2007

A layered streamtube model for estimating waterflood performance has been developed. The model is suitable for microcomputer applications. Displacement mechanisms are represented with a linear Buckley-Leverett11 calculation including, if desired, the presence of a free gas saturation or mobile water saturation at the start of flooding. Areal sweep effects are included by using fixed streamtubes for various patterns. By considering production and pressure drop to be a function of cumulative injection, rather than distance of the flood front along a streamtube, the necessity for geometric factors is greatly reduced. Reservoir heterogeneity and vertical sweep effects are considered with the Dykstra-Parsons approach. Pseudo-relative permeabilities can be used to account for crossflow with the Hiatt-Hearn model4,5 for uniform vertical pressure. Using the proposed model, the factors having the greatest effect on performance can be determined. Buckley-Leverett effects, including production after water breakthrough and variations in mobility ratio, can be as significant as reservoir heterogeneity. The presence of free gas at the start of water injection is shown to have a significant impact.
A Comprehensive Black Oil Reservoir Simulator for Microcomputer Applications
Authors: Choo Y. K. , Welch V. S.
Published: December 2007

This paper describes an overview of the development of a comprehensive black oil reservoir simulator (PC-GEM). Design goals implemented, including efficient memory and data management, fast computing speed, user friendliness, and extensive reservoir engineering features are discussed.

PC-GEM simulation results are obtained for two previously published reservoir problems. Computing speeds on different microcomputer systems and a minicomputer are compared for the SPE three-dimensional gas injection problem.
The Importance of Data-Software Interfaces
Authors: Walsh J. W. , Brown S. L.
Published: December 2007

A problem for many microcomputer users is the difficulty of interfacing different software programs. Often the output and results from one program is the input and data needed for another. Most likely the two programs are by different software writers or venders, are incompatible and no means exists to easily interface the two. The ability to link data and petroleum application programs can be solved using data files and spreadsheet or database programs. This interfacing technique is performed by having the spreadsheet or database program reformat or reorganize the output of one petroleum application program for use as input for the next application program.
The Use of Microcomputer-Based Spreadsheet Analysis for the Assessment of Domestic Oil and Gas Reserves Replacement
Authors: Godec M. L. , Kuuskraa V. A. , Gieser S. M.
Published: December 2007

With today's turmoil in the oil and gas industry, assessing the costs of replacing domestic reserves has become increasingly complex. The recent changes in drilling costs, oil and gas prices, and tax laws have created a premium for quick and clear analysis of this complex problem. This paper presents the methodology, design, and implementation of a microcomputer-based system for assessing oil and gas reserves replacement. The main components of this model are a supply analysis model, a capital formation model, a reserve additions and production forecasting model and an integrating model that relates each of the components to overall domestic oil and gas supply and demand. Finally, the paper discusses several possible scenarios for future oil and gas reserves replacement.