bluuebunny/crossref_metadata_2025 huggingface dataset:
Production of High Quality Crude Oil From Northern Great Plains Province Coal
Authors: Cochran Neal P.
Published: December 2007

Introduction

The most abundant fossil fuel reserve in the U. S. is in the form of coal. This resource constitutes over 80 percent of our recoverable fossil fuel energy—some four times the quantity of all the oil, gas, tar sands, oil shale, and bituminous rocks combined. About 40 percent of this lies in the Great Plains deposit as lignite, subbituminous and Plains deposit as lignite, subbituminous and bituminous coal. This paper projects a potential process for recovery of high quality potential process for recovery of high quality crude oil from these coals and presents an estimate of cost for a commercial-scale plant.

The process to be used in this plant of the future is an outgrowth of work done by industry and Government, some of which is currently under way. A substantial portion of this work was performed for the Office of Coal Research and has been reported elsewhere. Estimated costs have been extracted from Office of Coal Research reports modified to reflect scale and more recent process improvements.

To obtain a good relationship of processes, we have chosen from OCR contracts with Consolidation Coal Co- [Continental Oil], The Pittsburgh and Midway Coal Mining Co. [Gulf Oil Pittsburgh and Midway Coal Mining Co. [Gulf Oil Co.], Arco Chemical Co. (Atlantic Richfield], FMC Corp., Hydrocarbon Research, Inc., The M. W. Kellogg Co., Institute of Gas Technology, Westinghouse Electric Corp., West Virginia U., Iowa State U., Pennsylvania State U. and the U. of Utah. Work performed by the Bureau of Mines has been considered, along with work on advanced power cycles by Avco Corp. and American Electric Power. No claim is made that these organizations endorse or subscribe to this projected plant. In fact, a number of the projected plant. In fact, a number of the estimates are somewhat more pessimistic than those from the companies. Some, however, are more optimistic. We should like to call the over-all projection "realistically conservative".

THE RESOURCES

In considering methods to put the nation's coal resources to their best use, one immediately thinks of both other energy resources and markets and concludes that the major effort must be in the field of energy. This means that the coal processing plant of the future will be large—comparable in size to a modern petroleum refinery—with a nominal capacity of 100,000 to 200,000 B/D, with the coal mine serving the plant being very large by today's standards. plant being very large by today's standards. The process requires large reserves for which many Western deposits are ideal—a large reserve can be put together, the coal quality is good for a number of processes, and, perhaps most important, the coal seams are ideally suited to the most efficient modern mining methods. Many of the coal seams are 75 to 100 ft thick, with little overburden.
Higher-Order Implicit Flux Limiting Schemes for Black Oil Simulation
Authors: Rubin B. , Blunt M. J.
Published: December 2007

Conventional Black Oil models normally use single point upstream weighting for mobility terms. This is known to give rise to significant levels of numerical dispersion. Several higher order schemes including Godunov's scheme, Flux Corrected Transport, and two-point upstream mobility weighting have been suggested for use in explicit or IMPES simulators to improve accuracy. FCT and Godunov's scheme cannot easily be applied to fully implicit models, while the unconstrained two-point upstream method is unstable for purely hyperbolic systems and is best suited for IMPES models. The use of higher order schemes in reservoir modelling has thus been extremely limited.

In order to remedy this situation, we derive a total variation diminishing (TVD) higher order scheme which can be applied to both fully implicit and IMPES Black-Oil models. We develop IMPES and fully implicit analogues of these schemes for use in standard Black Oil models and discuss their relationship to commonly used mobility weighting schemes (mid-point, single-point upstream, two-point upstream and single-point downstream).

The TVD mid-point scheme is a temporally first order version of the second order TVD flux limited Lax-Wendroff scheme. The TVD criterion ensures that oscillations which would have been produced by unconstrained second order schemes never arise. The unconditional stability of the fully implicit TVD mid-point scheme is guaranteed, since the limiter is evaluated along with the fully implicit flux terms. The IMPES implementation has a stability limit which is half that of the first order single-point upstream scheme.

Results using the IMPES and implicit TVD scheme in a modified commercial Black Oil code (VIP) are presented for three test problems. The first test, which is used to determine the order of the scheme, is the one dimensioned waterflooding of a slightly compressible oil reservoir (fully implicit formulation). The second test, for scheme accuracy, is the two dimensional water flooding of one-quarter of a 5 spot pattern (IMPES and fully implicit formulations) and the third test, again for accuracy, is the coning of water in a two dimensional radial (R-Z) coordinate system.

The results of the above examples are compared with standard first order calculations. In the examples presented, the TVD scheme produced more accurate results from models using one-seventh (and one-fourth) the number of blocks, resulting in a better than four-fold (and three-fold) saving of CRAY XMP CPU time.
The Grid Orientation Effect in Reservoir Simulation
Authors: Brand C. W. , Heinemann J. E. , Aziz K.
Published: December 2007

In the solution of adverse mobility ratio displacement problems by five-point difference schemes fluids appear to flow along grid lines. This results in solutions that depend on the orientation and size of the grid. Hence different results are obtained when, for example, the same one-quarter five-spot problem is solved by grids that are parallel and diagonal to the line joining the injector and the producer. This Grid Orientation Effect (GOE) is a result of coupling between the anisotropic numerical diffusion and the physical instability of the displacement front. In this paper, a linear stability analysis is applied to the finite difference equations to examine the interaction between numerical diffusion and the growth of numerical errors due to physical instability. The results show that in general the GOE cannot be overcome with grid refinement. For a certain range of parameters, however, first the GOE decreases under grid refinement, reaching a minimum, and then increases again on finer grids. A technique is provided for estimating reasonable block size for a given displacement problem.
An Efficient, Three-Dimensional, Fully Coupled Hydro-Thermo-Mechanical Simulator: FEHMS
Authors: Kelkar S. , Zyvoloski G.
Published: December 2007

Hydro-thermo-mechanical effects in fractured rocks are important in many oilfield processes. Modeling these effects is made difficult by the fact that the governing equations are nonlinear and coupled, and the problems to be solved are three dimensional. In this paper we describe a numerical code developed for this purpose. The code is finite element based to allow for complicated geometries, and the time differencing is implicit, allowing for large time steps. The use of state-of-the-art equation solvers has resulted in a practical code. An example is presented to demonstrate the effects of matrix expansion, due to pore pressure and heating, on fracture opening due to fluid injection, and induced stress changes at a distant well bore.
A Fully Coupled, Fully Implicit Reservoir Simulator for Thermal and Other Complex Reservoir Processes
Authors: Mifflin R. T. , Watts J. W. , Weiser A.
Published: December 2007

This paper describes a formulation for fully coupled, fully implicit reservoir simulation. This formulation is implemented as an option within a framework that already supports IMPES and sequential semi-implicit formulations. The resulting capability has received extensive use for the modeling of thermal processes, and has been used successfully to model coning and naturally fractured reservoirs as well.

This formulation differs from the most commonly-used approach in two ways.

Its equations are derived using the volume balance approach. This gives the resulting equations physical meaning that can be helpful in understanding the simulator's behavior. Also, it makes it possible to incorporate the resulting capability into an existing simulator that is based on the volume balance equations. In isothermal cases, it uses pressures and moles as the primary variables. When the thermal option is invoked, energy becomes the additional primary variable, rather than temperature. This avoids the complication of having to change variables when a phase disappears. Saturations and temperature are treated as functions of the primary variables.

A procedure based on the Newton-Raphson method is used to solve the resulting nonlinear equations. This procedure incorporates several techniques to enable or improve convergence in difficult circumstances.

The paper includes descriptions and discussions of the resulting simulator's performance in several examples.
Development of a Thermodynamically Consistent, Fully Implicit, Equation-of-State, Compositional Steamflood Simulator
Authors: Brantferger K. M. , Pope G. A. , Sepehrnoori K.
Published: December 2007

A thermodynamically consistent, fully implicit, compositional, equation-of-state, steamflood simulator is described. The formulation uses a single set of primary variables-overall component mole numbers, total fluid enthalpy, and pressure-to linearize the finite difference forms of the component conservation equations, the energy conservation equation, and the pore volume constraint. These primary variables constitute a thermodynamically independent set; subsequently, they may be applied throughout the reservoir, supplanting the use of variable substitution. The resulting nonlinear system of equations is solved using the Newton-Raphson method to update the primary variables. At each iteration, local equilibrium is computed isenthalpically using a vectorized, Newton-type entropy maximization algorithm combined with a Gibbs stability test that yields the number of phases, the phase mole numbers, and temperature of the fluid mixture. This is the first time that such an approach has been taken within a steamflood simulator. Finally, examples are given that illustrate the importance of phase behavior on the residual oil saturation to steam.
Yield Points in Oilfield Cement Slurries
Authors: Clark P. E. , Sundaram L. , Balakrishnan M.
Published: December 2007

The determination of yield points in cement slurries is important in the overall description of slurry flow properties. Yield points affect both the start-up pressure after a temporary shut-down and void filling properties of cements. Values for the yield point are normally obtained by extrapolation of rotational or tube flow rheometer data. This technique is subject to both experimental and analytical errors.

Recently, a number of papers have described a more direct method of measuring yield points in slurries. A rotational viscometer equipped with a vane rather than a bob can be used to accurately measure yield points. The yield surface with the vane test fixture is in the fluid rather than at a fluid-solid interface as it is with a solid bob or a tube flow apparatus. Experiments with a vane fixture using a shear rate controlled rheometer can be subject to errors caused by wind-up of the torque spring. In this study a controlled stress rheometer was used to circumvent these problems.

Yield points for various oilfield cement slurries are presented. Data reflect the differences in additives, aging time and water content. The vane technique can be used to produce accurate and reproducible measurements of yield points in cements. Using a controlled stress instrument has a number of advantages in making these measurements.
The Economics of the West Virginia Natural Gas Exploration and Production Industry, 1977-1987
Authors: Iledare W. O.
Published: December 2007

In this paper, the structure, conduct and performance of the West Virginia natural gas producing industry is discussed. The competitiveness of the gas industry is measured empirically using the concept of concentration ratio and other features of industry structure. Trend analysis of the industry activities and outcomes shows no evidence of "market power" among West Virginia gas producers. The general drilling trends in West Virginia paralleled those of the entire U.S. Similarly, the trends in new gas discoveries, real wellhead price, gas exploratory drilling, to a large extent, are closely related. It was noted, however, that oil and gas operators in West Virginia took less risk in exploratory drilling between 1981-1987. It would appear that more exploration activities must be undertaken to reverse the current downward trends in new reserve additions in the 1990s.
Energy Considerations Associated With the Mechanics of Hydraulic Fracture
Authors: Advani S. H. , Lee T. S. , Moon H.
Published: December 2007

The relative contributions associated with the fracturing fluid dissipation and formation fracture toughness mediated energies play a pivotal role in the design and potential optimization of hydraulic fracture evolution in multi-layered reservoirs. A critique of the salient hydraulic fracture process controllable and uncontrollable parameters is presented. The roles of fracturing fluid rheology, flow rate, reservoir elastic properties, fracture toughness values, and in situ stress contrasts are highlighted by evaluating fracture propagation in isotropic models with pre-defined fracture geometries as well as a symmetric three—layered elliptic crack model. Model validation is conducted by comparison of selected numerical results from these simplified models with previously reported model responses. Application of the formulated concepts is illustrated in terms of hydraulic fracture configuration evolution.
Dukhan Field Multiwell Corrosion Study
Authors: Sharshar A. E. , Nutt R. L. , Smith P. M.
Published: December 2007

Multi-well Data base techniques greatly facilitate the storage, retrieval and manipulation of well log data.

This paper reviews a multi-well approach to the analysis of corrosion logging measurements across 50 wells in the Dukhan field.

The objective of the study was to understand corrosion phenomena throughout the field and to determine the relationships between corrosion in different wells.

Multi-well techniques to optimize the normalisation of logging tool responses to metal losses are described.

Dukhan field production/injection and corrosion problem history is reviewed followed by a description of the basic Corrosion Evaluation logging tool measurements and their incorporation into the multi-well data base.

Results, both field wide and selected individual well, are presented and discussed. These results indicate that the most significant corrosive mechanism is inner wall erosion in the dump flood injection wells. However mild, outer wall metal loss is observed, in some cases, across the un-perforated aquifers suggesting the possibility of other corrosion phenomena which should be monitored in future casing corrosion evaluation programs.
Two-Way Man-Machine Communication Systems for Computer Production Control
Authors: Maruska V.J.
Published: December 2007

American Institute of Mining, Metallurgical and Petroleum Engineers Inc.

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

Profitable implementation of Computer Production Profitable implementation of Computer Production Control (CPC) on a large-scale basis requires a highly sophisticated system for man-machine communications. One such system has been developed and is currently undergoing further refinement. Specific factors considered in its development include:

Minimum initial hardware investment with flexibility to incorporate less expensive hardware as it becomes available. Two-way communications with total security. Device-independent system capable of communicating with teletypewriters, cathode ray tubes, card readers, typewriters, matrix keyboard consoles, line printers, etc., with equal ease. Input/output designed for use by nontechnical personnel with maximum manpower efficiency. Message handling software is user oriented and FORTRAN compatible.

Introduction

Computer Production Control (CPC) is the concept of computer controlled telemetering to automatically, remotely, and continuously perform control, measurement, alarm monitoring, and data-gathering functions associated with oil and gas production. Computer hardware is currently production. Computer hardware is currently available which will enable operating several thousand wells under a CPC concept with the aid of a single CPC computer system. However, two general problem areas are encountered in problem areas are encountered in converting to such a total CPC concept:

Some leases cannot justify physical control or monitoring due to geographic, economic, or other considerations. However, a total CPC concept requires that all data of a specific category must be stored within the computer system using the same format regardless of the method originally employed to acquire this data. Incorporating these leases into a CPC operation therefore requires that the data-gathering functions be manually performed and reported to the computer via some type of remote input/output station.
Status of New Wave Forecasting Techniques
Authors: Baer Leodolph , Adamo L.C. , Hamm D.P.
Published: December 2007

American Institute of Mining, Metallurgical and Petroleum Engineers, Inc.

Basic concepts of ocean waves as used in wave-forecasting are reviewed; the historical development of forecasting in the U. S. A. is traced from the first empirical approach of Sverdrup-Munk to the spectral techniques of Pierson-Tick-Baer, and Baer-Adamo-Hamm. Pierson-Tick-Baer, and Baer-Adamo-Hamm. The advantages and shortcomings of the various systems are discussed. Examples of the use of spectral forecasts are given, and some remarks are made on future work.

Introduction

There have been many new developments in wave forecasting within the last few years. In this paper we will attempt to put these in perspective, explain them, show the advantage of perspective, explain them, show the advantage of using these new techniques, and admit the outstanding problems which have not yet been solved. Modern unified physical concepts allow this explanation to be elementary and yet comprehensive. Before we really understood what was going on we had to resort to many complicated empirical and semi-empirical methods which were wrong, but, happily, such is no longer the case.

As a basis for this discussion, let us consider what a wave field really is. When we look at the surface of the sea over which wind is blowing, the sea looks quite irregular. Figure 1 is a contour analysis of an area covering 2670 ft. by 1770 ft. The wind was about 16 knots, significant wave height about 7 ft. Short wavelengths have been smoothed out. The shaded areas are troughs. Occasionally the waves peak up and are shaped like pyramids or mounds. Some of the waves have relatively long crest lengths; others appear to be higher or lower, or moving in different directions. Our first order of business is to define the sea surface in some precise manner so that we can objectively compare various techniques.

In the bottom trace in Figure 2, we have reproduced a wave record that could have been taken with a wave staff, a bottom mounted pressure sensor, a floating accelerometer, or an pressure sensor, a floating accelerometer, or an airborne altimeter. This record is linearized for simplicity. A real case would have peaked crests and flattened troughs. The first methods of analyzing such records in detail were to measure the amplitudes of each wave and compute various statistical descriptions such as the mean of the highest 1/3 of the waves, which has been defined as the "significant height". This value for significant heights was chosen because it approximates what a seaman typically estimates for the general height of the sea. Depending upon our method of recording and our definition of just what constitutes a wave, we can get different values for significant heights. There are no accepted criteria for either of these, although some of us have used the requirement that a wave is not a wave unless it both begins and ends at the mean water level.
Measurement of Steam Injection Tubing Heat Losses Using Pressure/Temperature Survey Data
Authors: Wheaton L. D.
Published: December 2007

The steamflooding of deep reservoirs requires the use of insulated tubing to minimize heat losses and maintain high-quality steam at the sandface. In order to evaluate the effectiveness of tubing used, techniques are needed to measure the heat loss in the wellbore and calculate the thermal conductivity of the insulation.

This paper presents the results of tubing analysis in a well of 4250 ft depth using pressure-temperature survey data. The problem of determining the bottom-hole steam quality under normal operating conditions was overcome by setting the inlet quality at a level estimated to result in zero quality at the sandface. This allowed the calculation of bottom-hole enthalpy and total heat loss using pressure and temperature measurements. The performance of the insulated tubing was evaluated by adjusting variables in a wellbore simulator to obtain a match of the experimental data recorded at several elevations.

Results of the test concluded the heat loss in the injection well was 130% higher than predicted using anticipated tubing properties. The heat loss was uniform through the tubing, and resulted from poor insulation performance. The simulation results eliminated the possibility of heat loss due to refluxing in the tubing annulus.
Evolution of a Successful Steamdrive in a Geologically Complex, Steeply Dipping Reservoir at South Casper Creek Field, Wyoming
Authors: Stevenson V. M. , Mullen C. E.
Published: December 2007

South Casper Creek Field provides a field case history of previous and current thermal activities, testing several steamflood strategies in a steeply dipping, geologically complex reservoir with the presence of an active edgewater drive. The thermal experience in the field indicates that geologic factors are the dominant influence on steamflood performance. The accurate interpretation and proper application of an improved geologic model directly affects oil production response.
Fosterton Northwest: Post In-Situ Combustion Corehole Analysis
Authors: Ostapovich E. , Ross M. F.
Published: December 2007

Results of core analysis, including displacement efficiency estimates and the effects of in-situ combustion on reservoir rock and fluids are presented in this paper. High vertical sweep efficiency is evident contrary to predictions by most thermal simulators that little heat would be transported below the burnt zone at this distance from the injector. The usefulness of petrophysical analysis as a diagnostic tool is also demonstrated.
Carbonate Scale Formation in Thermally Stimulated Heavy-Oil Wells Near Lloydminster, Saskatchewan
Authors: Erno B. P. , Chriest J. , Miller K. A.
Published: December 2007

Carbonate scale deposits have been determined to be a major cause of downhole screen plugging in steam stimualted wells in several Lloydminster, Canada heavy oil reservoirs. Lab experiments and analyses of produced fluids have identified the most likely mechanism of scale formation, and a simple method of using compositional data to determine whether downhole scaling is occurring is presented.
Minifrac Analysis for Heterogeneous Reservoirs
Authors: Soliman M. Y. , Kuhlman R. D. , Poulsen D. K.
Published: December 2007

General minifrac analysis type curves for analysis of heterogeneous formations have been developed and are presented in this paper. These type curves apply to a wide variety of formations including coalbeds and naturally fractured formations. The new type curves have been developed for the Perkins and Kern model. The paper presents the development of equations and type curves. and discussion of the technique and criteria for their application.

Conduct and results of a minifrac test in a coal seam are presented in this paper. The test is analyzed using the developed technique. The data in this case fits the new type curve extremely well. The match with existing type curves was poor.
Analyzing the Two-Cycle DST: Quantifying the Horner Plot Error
Authors: Durrett Steven D.
Published: December 2007

The two-cycle drill stem test, consisting of an initial flow period, an initial shut-in period, a second flow period and a second shut-in period, remains the most common type of test run in the field. Unfortunately, the most widely used method of analyzing data for these tests can result in significant errors. By far the most widely used method for DST analysis is a Horner plot prepared using Tp = t1F + t2F. In this method, an average flowrate is used in the calculation. Earlougher1 suggests that plots can be based on Tp = t2F or Tp = t1F + t2F, but is decidedly vague on when one is preferable to the other. Actually, the selection of Tp is not nearly as significant as is the selection of the flowrate to be used in the calculations.

In practice it seems that most tests are analyzed with Tp = t1F + t2F presumably because it generates a straighter line on the Horner plot. Unfortunately, the slope of this straight line can be very misleading. This is not to say that this slope is "wrong" since Horner slope in and of itself is not the parameter we are seeking. Only when combined with a flowrate does the Horner slope take on any physical significance. Thus while a Horner slope itself cannot be "wrong, " the combination of a Horner slope with an inappropriate flowrate can result in a "wrong" answer. Conversely any slope can be the right slope if it is combined with the appropriate flowrate. Thus we must remember that any discussion of Horner slopes must be rate-specific.
Data Acquisition, Analysis, and Control While Drilling with Horizontal Water Jet Drilling Systems
Authors: Dickinson Wade , Pesavento Michael J. , Dickinson R. Wayne
Published: December 2007

Two different horizontal water jet drilling systems have been developed and extensively field tested. The first, the Ultrashort Radius Radial System (URRS) is built around 32 mm (1-1/4 inch) coiled tubing and provides multiple 30 to 60 m (100 to 200 foot) radials from a vertical borehole. Accuracy is ± 2 to 3° in vertical trajectory.

The second system, the Remotely Piloted System, uses 114 mm (4-1/2 inch) conventional flush joint tubing and is designed to drill for many kilometers (miles) with high three dimensional accuracy. Both systems incorporate Control While Drilling of the radial and provide real-time acquisition and display of drill performance with derived formation properties.
Potential Cumulative Impacts of Environmental Regulatory Initiatives on U.S. Crude Oil Supplies
Authors: Godec Michael L. , Biglarbigi Khosrow
Published: December 2007

A number of legislative and regulatory initiatives being considered to protect the environment could affect the economics of U.S. oil and gas exploration and production (E&P). Not all environmental statutes require the Environmental Protection Agency (EPA) or other regulatory agencies to consider costs and/or energy impacts when establishing regulations or standards. Even when energy impact analyses are performed, they are often limited in scope, because they generally only consider the impacts associated with a specific regulation, and almost always assume no impacts from regulations in other areas. Many have expressed concerns that the cumulative costs of multiple regulatory initiatives could significantly impact U.S. oil and gas operations. This paper summarizes the results of a more comprehensive assessment of the potential cumulative energy and economic impacts of environmental regulatory initiatives on U.S. crude oil supplies (ICF Resources, 1990).

The economic recovery potential of various crude oil resource categories at four constant oil prices -- $16, $20, $24, and $32 per barrel (in 1988 dollars) - was considered in this analysis. Future supplies from four categories of U.S. crude oil resources were evaluated: oil recoverable from the continued conventional production of known onshore Lower-48 fields, oil recoverable from future infill drilling and waterflood projects in known onshore Lower-48 fields, oil recoverable from future enhanced oil recovery (EOR) projects in known onshore Lower-48 fields, and oil recoverable from onshore and offshore crude oil fields remaining to be discovered in the Lower-48 and Alaska (onshore and offshore).

The results of this analysis clearly demonstrate that increased regulations on U.S. crude oil E&P operations can have a significant impact on potential ultimate crude oil recovery. The extent of regulations imposed clearly will determine the level of impact, but the results show that significant impacts are felt over a wide range of regulations, over a wide range of crude oil prices, and at two levels of development for extraction technologies. All resource categories analyzed in the study are impacted by the regulations evaluated.
Optimum Well Location for Steamflooding Steeply Dipping Reservoirs
Authors: Hong K. C.
Published: December 2007

A numerical simulation study was conducted to determine the optimum injector location for steamflooding steeply dipping reservoirs with five-spot pattern configurations. The model reservoir has either 20° or 45° dip, is bounded by an updip gas cap and a downdip edgewater and is steamflooded with one, two, or three five-spot patterns in the direction of dip.

The study showed that steamflood performance in dipping reservoirs can be improved by placing the injector downdip from the pattern center. The optimum injector location for most situations was found to be about halfway between the pattern center and the downdip producer row. This off-center, downdip steam injection produces the highest steamflood oil recovery among all injection locations considered in the simulation study.
Fracture Growth in the Presence of Highly Stressed Layers.
Authors: Wang J-J. , Clifton R. J.
Published: December 2007

The paper presents and discusses results of hydraulic fracturing simulations performed for a two-layered reservoir bounded by highly stressed formations. Each reservoir layer was 75 feet thick, separated by a 50 feet thick impermeable formation and bounded on the other sides by similar barrier formations. Stresses in each barrier formation was either 1200 psi or 600 psi greater than in the reservoir layers. Fractures were initiated either from the upper payzone or the highly stressed barrier separating the payzones. Two fracture treatment schedules were considered for the different fracture initiations. In the first treatment, only neat fluid was used; the second treatment incorporated proppant concentrations varying from 1 to 6 lb/gal after pumping 2880 barrels pad volume. For both treatments, Newtonian fluid, with 100 cp viscosity, was injected at a rate of 3 0 bpm for a total slurry injection volume of 7200 barrels. The calculated geometry and width profiles along the wellbore are provided on completing the injection. Fracture length, height, treatment pressure, and maximum opening histories are also presented. Contours of fluid fronts, proppant fronts, and proppant are demonstrated for one case.

The fracture initiated in the highly-stressed middle layer showed: (i) a bell shape fracture with lengths of 400 ft in both payzones but of shorter length in the middle layer at the early pumping stage, (ii) the fracture opening at the wellbore decreased as the fracture initially migrated into the low stress payzone and increased after the fracture reached the outer barriers, and (iii) a higher net fluid pressure was required to initiate the fracture in comparison to the fracture initiated in the payzone.
Fracture Half-Length and Linear Flow in the South Belridge Diatomite.
Authors: Nott D. C. , Hara S. K.
Published: December 2007

The South Belridge Diatomite is a low permeability, high porosity, hydraulically-fractured reservoir. Infill drilling of the South Belridge field focused attention on fracturing. The three topics covered in this paper are a review of re-fracturing performance, an estimate of existing hydraulic fracture length, and application of analytical and simulation models to analyze and predict reservoir behavior.

Re-fracturing treatments successfully extended existing fractures. The productivity of seventeen wells increased 17% for eighteen months after stimulation. The fracture half-length of existing wells is estimated to be 115’ [35 m], while the no flow boundary is known to be 165’ [50 m]. The half-length is calculated based on the productivity of 20 wells and their reservoir pressure profile after 5 years of depletion. It is assumed that the reservoir is still in transient linear flow.

An areal simulation is undertaken which validates the application of linear flow equations to this reservoir. The simulation is also used to predict the incremantal production due to longer fractures in new wells. As the fracture length increases, the marginal production benefit decreases.
Risk Analysis: Over-All Chance Of Success Related To Number Of Ventures
Authors: Campbell W.M. , Schuh F.J.
Published: December 2007

Publication Rights Reserved

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

We can learn much from the laws of probability that will help us in making wise decisions about exploration programs. Any company searching for mineral deposits wants to have a "reasonable" chance of making money. It is not enough to know that we will make money "on the average." In fact, we must be fairly certain of making a profit from a limited investment.

In our paper we are concerned with two factors in an exploration program:the chance of finding an oil field on any given exploration attempt, such as drilling a well, andthe value of the oil field found.

Both of these variables bear on the reasonable chance of making money.

We know, for instance, that with a 10 per cent chance of success we will not always succeed in 10 per cent of the number of attempts made.

The size of the field found obviously affects the value of the successful find. Most oil fields found contain less oil than the "average" field. The most probable size of any one discovery is much less than the average size of all discoveries. So to have a high chance that the average size of our finds will be close to the average size of all finds, we must find many fields.
Pressure Falloff Tests of New Coal Wells
Authors: Seidle J. P. , Kutas G. M. , Krase L. D.
Published: December 2007

This paper demonstrates field application of pressure falloff testing and analysis methods to new coal degas wells in the San Juan Basin. These tests have provided absolute coalbed permeability, wellbore skin, and initial reservoir pressure. Effects due to free gas and gas desorption on pressure falloff tests are considered. The effects of sorption compressibility are shown to have a significant impact on skin but not on permeability. Influence of the duration of the injection and shutin periods on the design and analysis of coal well PFOTs is also discussed. Field examples of both pre- and post-stimulation falloff tests are presented.
Successfully Drilling Severely Depleted Sands
Authors: Newhouse C. C.
Published: December 2007

Development drilling normally involves less risk since many drilling parameters are known; however, in mature fields operating under depletion or limited water drive mechanisms, this is not always the case. Although the reservoir pressures are known, depleted sands can present serious drilling problems and substantial cost increases. Differential sticking of drill pipe, casing, and logging tools; and tight hole conditions due to excessive filtrate loss and cake buildup are some of the problems which may occur. Additional casing strings may also required to cover these sands. Effectively plugging the depleted intervals is the key to preventing most of these problems.

Experience has been limited drilling through numerous, severely depleted sands for prolonged periods. The focus of this paper will be upon the well design and water-based drilling fluid considerations which have proven successful under these conditions. Drilling practices, specially designed plugging products used, and research developments in plugging permeable formations using a new test apparatus will also be presented. Application of these practices should prove effective in any geologic area containing normal sandstone-shale sequences such as the Gulf of Mexico.

Three examples of the most extreme case histories will be exhibited. These wells had sands which were exposed to differential pressures exceeding 4700 psi with as many as ten sands and differentials over 2500 psi exposed at one time. To further complicate matters, all the wells were directionally drilled with hole angles ranging from 20 to 42 degrees.
New Technology Improves Natural Diamond Bit Performance
Authors: Jackson R. , McKinney J. , Rogers T. , Smith L.
Published: December 2007

While the emphasis in diamond bit technology has increasingly shifted toward PDC and TSP technology, two recent innovations, detailed in the paper, are directly applicable to the improvement of natural diamond bits.

Use of numerically controlled milling machines, in conjunction with computerized bit design, allows a reduction in the number of diamonds used on a bit, thus increasing penetration rates through increased diamond loading. The development and use of diamond coating techniques, which offers the possibility of improving the bit-to-matrix bond, allows increased diamond exposure on the face of the bit. When these enhanced bits are coupled with a medium speed, medium torque drilling motor, significant performance increases are realized.

The paper provides analysis of bit runs employing a significant number of enhanced diamond bits in a variety of sizes, hole intervals and well applications, primarily in western Oklahoma’s Red Fork formation, which is typically a medium to hard alternating sand/shale sequence. These runs are compared to more than 100 conventional natural diamond bit motor and rotary runs.

In addition, operating limitations and recommendations are outlined for the use of enhanced natural diamond bits, which is shown to have resulted in savings of two to three days per well versus conventional diamond bit motor applications.
The Critical Buckling Force and Stresses for Pipe in Inclined Curved Boreholes
Authors: Schuh F. J.
Published: December 2007

A number of papers have been presented that define the critical buckling force in inclined straight holes. This paper presents a method for calculating the critical buckling force in vertically and laterally curved and inclined boreholes.

The paper includes methods for computing the bending stress of buckled pipe with tool joints. It also includes a method for computing if the deflection of the pipe at midspan will cause the pipe body to touch the wall of the hole. This approach resolves the question of how tool joints affect the critical buckling force, the curvature of the pipe, and maximum bending stresses.

The paper includes plots of the critical buckling force versus hole curvature for common sizes of drillpipe and Heviwate. We also include plots of the maximum bending stress versus axial force and hole curvature for several sizes of drillpipe and Heviwate.
A New Bottomhole Assembly Analysis Program for the Prediction of the Borehole Path Based on a Sophisticated Static Algorithm
Authors: Dahl T. , Schmalhorst B.
Published: December 2007

The theoretical bottomhole analysis of drillstring assemblies and the prediction of wellbore trajectories play an important role for directional drilling. Time constraints, cost efficiency and accuracy require computer aided planning of the drilling process. As such a program should be user friendly and, at the same time, accurate, a program was developed for personal computers, combining simplicity even for less experienced users with complexity as regards the sophisticated computation of the directional drilling behaviour of a variety of bottomhole assemblies.

The program is based on a newly developed three dimensional static drillstring analysis model for arbitrarily shaped boreholes. For any string assembly the wall contact problem is solved using a non-linear wall potential equation. The program allows sophisticated wellbore prediction calculations using an improved version of Ho's formula.

The numerical results could be verified by field data; even the walk tendency is well predicted.
Cuttings and Waste Mud Disposal
Authors: Arnhus K. M. , Slora G.
Published: December 2007

This report reviews the case history installation of a cuttings handling system (CHS) designed for transportation of drill cuttings to container loading stations for shipment to shore. The system was installed on Norsk Hydro a.s (NH) Oseberg C Platform, PDQ (fig. 1 &2) Oseberg field in the North Sea. Early identification of future stricter regulations by Norwegian Authorities made it possible to design and purchase a system for installation during the construction phase of Oseberg C platform modules and comply with the coming regulations. Costly infield modifications at a later stage was thereby avoided. The logistics of cuttings handling to shore and operational limits are described. Fig 1Platform looking west.Fig 2Platform looking north.
Managing Accident Prevention and Personnel Training in Developing Regions of the World
Authors: Overturf S. H.
Published: December 2007

An accident prevention program and a person-nel training program were established for use by drilling personnel in developing countries.Included in the training program was increased emphasis of operations manage-ment.This paper will review considerations involved in the implementation of these accident prevention and training programs for developing and developed nations will be compared; this will show the impact of training and accident prevention performance for drilling personnel in developing areas of the world.
Performance Characteristics of Drilling Equipment Elastomers Evaluated in Various Drilling Fluids
Authors: Kubena E. , Ross K. C. , Pugh T. , Huycke J.
Published: December 2007

The type of elastomer chosen for use in drilling equipment can mean the difference between a normal service life or sudden unpredictable failure. Drilling fluids can chemically alter elastomers in equipment used for drilling oil and gas wells. The degree and magnitude of this interaction depends on the type of the drilling fluid, temperature, pressure, and chemical formulation of the elastomer. Certain components of drilling fluids, such as the base oil in an oil-base mud, can cause changes in weight, volume, and hardness of elastomeric compounds. These changes can affect the resulting performance of the elastomer.

This paper will discuss different types of elastomeric compounds and their performance in various drilling fluid systems. The focus will be on elastomers used in downhole drilling equipment such as stator material which is an important component in positive displacement motors (PDMs). Field data concerning the performance of certain elastomers in specific drilling fluids will be discussed. Results of recent elastomer immersion tests in various fluids used in the drilling industry are presented.
Drilling and Production of Khuff Gas Wells, Saudi Arabia
Authors: Turki W. H.
Published: December 2007

The Khuff Gas Development program involves many disciplines from the early planning stages to the final producing stage. This paper will highlight the plans for drilling and producing the primary well configurations for 4-1/2 in. (114.3 mm) and 7 in. (177.8 mm) Khuff gas completions in Saudi Arabia.

The problems of abnormally high pressured gas and/or water zones, lost circulation, water sensitive shale, and high temperatures that are encountered while drilling a Khuff gas well will be discussed as well as the high solids deflocculated polymer (HSDP) drilling fluid that has been developed and field proven at densities as high as 156 pcf (20.9 ppg) and sustained BHSTs above 300° F.

The downhole completion and production considerations of these wells will be covered and certain aspects interrelated to this discussion such as fluid properties, safety concerns, scale and corrosion will be addressed.

Finally, the possible causes and solutions for annular pressure that is sometimes observed after cementing the abnormally high pressured gas zones with 160 pcf (21.4 ppg) cement slurries will be reviewed along with operating experience gained to-date to provide an overall picture.
Synthetic Retarder for High-Strength Cement
Authors: Brothers L. E. , Chatterji J. , Childs J. D. , Vinson E. F.
Published: December 2007

A synthetic polymer cement retarder has been designed to provide extended pumping times for cement slurries, while having minimal effect on compressive strength development. When compared to traditional lignosulfonate cement retarders, the synthetic polymer provides better response properties, and it is chemically more uniform. Deep wells with bottom-to-top temperature differentials of 150°F have been successfully cemented with slurries containing this retarder.
Cost-Saving Applications of Harsh Environment Jackups and Associated Contracting Philosophy Implications
Authors: Hinton R. O.
Published: December 2007

The three extra large harsh environment jack-ups (ELJU’s) currently under construction take North Sea jack-up capability into water depths exceeding 110 metres.

In addition to providing highly productive and safe exploration drilling capability, these units are also versatile tools for platform and template installation and drilling operations.

Significant facility cost savings are possible from ELJU applications.

Perceived risk of project exposure to rig non-availability or high dayrate may however deter Operators from selecting this drilling option and taking advantage of potential cost savi ngs.

This paper highlights cost saving applications. It also shows that there is a progressive, convergent, controlled-exposure path to contracting an ELJU and maximising potential cost savings in project situations.
TVD Control Using High-Accuracy Pressure and Deep Resistivity Measurements
Authors: Jones R. D. , Alvestad J. T. , Kjøsnes K.
Published: December 2007

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This paper describes the theory behind how high accuracy pressure gauges could be used, and how they were attempted used to verify the True Vertical Depth (TVD) of a 8 1/2" 800 m long horizontal section.

The paper also describes the successful use of resistivity as an alternative method for the verification of TVD in the same horizontal section.

The Troll field has accumulated oil as "thin" layers (12-26 m thick) in the order of 600 x 106 Sm3 OIP beneath the giant gas reservoir. Due to the anticipated severe gas coning problem, horizontal wells very accurately positioned relative to the OWC, are looked upon as a feasible way of commercial development of the oil.

Well 31/5-4AS was drilled with a 800 m long horizontal section within the intended target tolerance of + 2 m. By using real time resistivity and resistivity in memory mode, as a correction for MWD inaccuracy, the well was drilled within + 1.5 m relative to the Target horizon. Pressure surveys used as a third independant TVD indicator could not improve the perfect correlation between the two others (MWD and Resistivity). Pressure surveys were, in order to ensure a safe operation, postponed until the 6 5/8" production liner was run. The results from the pressure survey confirmed the validity of the theory but revealed that technical problems still exist.