bluuebunny/crossref_metadata_2025_split huggingface dataset:
A New System of Tools for Better Control and Interpretation Of Drill-Stem Tests
Authors: McAlister J.A. , Nutter B.P. , Lebourg M. 
Published: December 2007

Abstract
The Multi-Flow Evaluator (MFE) is a new system of tools providing an original approach in drill-stem testing. It improves control during the testing operation and gives a more accurate evaluation of the fluid recovered while providing additional pressure information for reservoir analysis. The tools are operated entirely by up and down motion of the drill stem. This up and down operation provides a positive means of control and offers easily observed surface indications of tool operating position. An unlimited number of shut-in and flow periods may be taken with this tool while in the hole. The key to the success of the MFE system of tools is the safety seal packer. Until this development, operation of the tools by up and down motion only had proven unreliable. The success ratio of the MFE now exceeds the ratio achieved by conventional tools. The equipment includes a 2,750-cc chamber in which a representative sample of the flowing formation fluid is trapped at the end of the last flow period and brought to the surface under pressure. The sample can be evaluated at the wellsite or transferred under pressure for laboratory analysis. The sampling feature of the tool allows a sample to be obtained from a reservoir which has suffered minimum influence from production. A representative sample can be obtained for laboratory or empirical analysis by employing a testing technique to minimize drawdown during flow periods. Interpretation methods to take advantage of this additional information are presented and supported by actual field examples.
Introduction
The Multi-Flow Evaluator (MFE) represents the most recent technical advance in formation testing. Drill-stem testing techniques prior to the MFE have been limited in three areas(1) operation, (2) recovery analysis, and (3) reservoir analysis. The tools in the MFE system allow maximum control during testing and provide test information superior to that obtainable with conventional tools. The system of tools and the operation procedures are described to illustrate the mechanical advantages over present tools.
JPT
P. 207ˆ
Sand Stresses Around a Wellbore
Authors: Risnes Rasmus , Bratli Rolf K. , Horsrud Per 
Published: December 2007

Abstract
We have studied theoretically the stresses in a poorly consolidated sand around a cylindrical well, assuming axial symmetry. Applying theories of elasticity and plasticity on this three-dimensional (3D) model, analytical solutions for all three stress components have been worked out.
The existence of a plastic zone around an uncased wellbore is confirmed, and the size of the zone is determined. When allowing an incompressible fluid to flow radially into the wellbore, a stability criterion describing the failure of the sand is found to exist. This criterion relates fluid flow forces to rock strength properties.
Consideration also has been given to the stress distribution around a cased hole. It is shown that a decrease in the size of the plastic zone relative to an uncased hole occurs.
Reliable Interpretation of Waterflood Production Data
Authors: Jordan J.K. 
Published: December 2007

Abstract
The most reliable method of interpreting the performance of secondary recovery water floods is through the use of the complete reservoir analysis. Although complete field data are not always readily available, the operator can usually make a quantitative interpretation of waterflood performance from information generally available on these projects. Water injection and oil and water production data, the time and location of water appearance, and the production behavior of individual wells can be utilized to obtain a positive measure of the sweep efficiency and oil recovery at any stage of depletion. The various methods of interpreting waterflood data have been examined to determine the degree to which these methods significantly describe waterflood performance.

Introduction
Expansion of secondary recovery waterflood operations in recent years has emphasized the need for thorough methods of evaluating the production behavior and performance of such projects. Through the use of sound engineering techniques, it is possible to determine the susceptibility of the reservoir formation to water flooding, to evaluate the efficiency of the project with respect to movement of flood water through the reservoir, and to predict the future oil recovery from the flood area. A continuing appraisal of the current and predicted behavior of the reservoir and of wells under flood can enable the operator to follow closely the progress of the flood throughout its operating life. In this manner, positive control of the water flood can be maintained and necessary steps can be taken to assure the success of the project.
Proper interpretation of behavior of secondary water floods depends upon a thorough understanding of the fundamental principles underlying the mechanism of the displacement of oil by water. Through controlled laboratory experiments and observation of the performance of many water-drive fields, produced both by primary and by secondary methods, knowledge has been obtained delineating the recovery process and the several factors that influence displacement of oil by water. In light of these studies, the engineer is able to apply this knowledge to interpretation of field waterflood performance and to obtain practical solutions of field operating problems.
Pore Volume Compressibilities of Sandstone Reservoir Rocks
Authors: Fatt I. 
Published: December 2007

Abstract
Pore volume compressibilities measured in tile laboratory on core samples are reported for typical reservoir sandstones at reservoir pressures. These compressibilities are different for each reservoir sample and cannot be correlated to porosity. The compressibilities are also functions of pressure.

Introduction
In recent years several authors have pointed out the importance of including pore volume compressibility of the reservoir rock in certain reservoir engineering calculations. Hall showed that in calculating the hydrocarbon volume of an undersaturated reservoir from the production per unit change in reservoir pressure, the neglect of rock compressibility could, in the extreme case of low porosity rock, lead to results in error by a factor of two. Hawkins and Hobson and Mrosovsky showed that both rock and interstitial water compressibilities must be included to achieve satisfactory accuracy in this calculation.
Although rock compressibility is an important reservoir property in these calculations, very few data are available. Hall made compressibility measurements on a few samples in a small pressure range. No other direct pore volume compressibility measurements have been reported. Geertsma discussed the elasticity of reservoir rock but did not present any new data. In this paper, rock compressibilities suitable for reservoir calculations are reported for a variety of sandstones typical of U.S. reservoirs. The measurements were made through a range of pressures which is also typical of reservoirs.

Experimental Procedure
Plugs 1 in. in diameter and 2- to 3-in. long were diamond drilled, 14 from cores from seven oil-bearing or potentially oil-bearing sandstone, one from a quarried sandstone, and another from a shallow, oil-free, pure orthoquartzite. The plugs were extracted in toluene, vacuum dried and then weighed. The plugs were then saturated with kerosene and reweighed. This gave pore volume. They were then again extracted in toluene, vacuum dried and jacketed in 0.004-in. thick copper foil. A short length of ¼-in high pressure tubing led from the jacket. The jacketed sample was then saturated with kerosene and placed in the hydraulic pressure cell as shown in Fig. 1. Movement of the mercury slug showed the change in pore volume of the sample under a given pressure change. Temperature was about 72° F for all measurements.
Comparison of Solutions to a Three-Dimensional Black-Oil Reservoir Simulation Problem (includes associated paper 9741 )
Authors: Odeh Aziz S. 
Published: December 2007

Summary
A comparison of solutions to a three-dimensionalblack-oil reservoir simulation problem is presented.The test of the problem and a brief description of theseven simulators used in the study are given.

Introduction
Seven companies participated in a reservoirsimulation project to compare the results obtained bydifferent black-oil simulators. The companies werechosen to give a good cross section of the solutionmethods used in the industry. The participants wereAmoco Production Co., Computer Modelling Groupof Calgary (CMG), Exxon Production Research Co., Intercomp Resource Development and EngineeringInc., Mobil Research and Development Corp., ShellDevelopment Co., and Scientific Software Corp.(SSC). The paper presents the text of the problem, acomparison of results in graphical form, and a briefdescription of each model. The descriptions weresupplied by the participants.
A variety of computers was used. Amoco usedIBM 3033, IBM 370/168, and Amdahl V/6. CMGused Honeywell 6000 DPS, and Exxon used Amdahl470/V5 and IBM 370/168. Intercomp used Cray-1and Harris/7. Mobil and SSC used CDC Cyber 175, and Shell used Univac 1110/2C Level 36. Thenumber of time steps and the central processor timesvaried considerably. Those interested in the actualvalues should contact the individual companies.
Except for Shell, all the participants usedsingle-point upstream mobility weighting. Shell used twopoints upstream. Constraints and data are given inthe text.

Statement of the Problem
Areal and cross-section views of the reservoir aregiven in Figs. 1 and 2. The grid system is given in Fig.1. Stratification and reservoir properties are given inFig. 2. The reservoir is initially undersaturated. A gasinjection well is located at Grid Point (1, 1), and aproducing well is located at Grid Point (10, 10).Pertinent data and constraints are given in Table 1.PVT properties and relative permeabilities are given in Tables 2 and 3. The participants were asked tomake the runs and report the results described below.
Runs To Be Made
Case 1
Let the bubble-point (saturation) pressure beconstant with a value equal to the original value.
Case 2
Let the saturation pressure vary with gassaturation - i.e., this is a variable saturation-pressurecase. The PVT lines at pressures above the calculatedsaturation pressures are parallel to the original line.

Results To Be Reported
The following results are to be reported.1. Plots of:a. Oil rate vs. time.b. GOR vs. time.2. Report annually and at abandonment:a. The pressures of the cell where the injectorand producer are located.*b. Gas saturation at Grid Points (1, 1, 1), (1, 1,2), (1, 1, 3),(10, 1, 1), (10, 1, 2), (10, 1, 3), (10,10, 1), (10, 10, 2), and (10, 10, 3).3. Report at the end of 8 years:a. Tables of gas saturation.b. Tables of cell pressures. *c. Tables of saturation pressures for the variablesaturations-pressure case. *
JPT
P. 13^
Stability of Piston-Like Displacements of Water by Steam and Nitrogen in Porous Media
Authors: Krueger David A. 
Published: December 2007

Abstract
Downhole steam generation leads to consideration of reservoir fluid displacement by a mixture of steam and nitrogen. The linear stability analysis of the steam condensation front has been generalized to include a non-condensing gas. Roughly speaking, the addition of nitrogen increases the likelihood of having fingers, but, compared with the no-nitrogen case, the fingers will grow more slowly.
Bottom Furrows and Estimated Currents in the Mississippi Delta Region
Authors: Adams Charles E. , Prior David B. , Coleman James M. 
Published: December 2007

Summary
A simple model of a neutrally buoyant, steady-state benthic boundary layer is used to examine the relationships between the dimensions of secondary roll vortices in the boundary layer and the spacing of a system of bottom furrows located offshore of the Mississippi Delta. The mean free-stream flow velocity predicted by the model, which creates the desired ratio between those two parameters, is an estimate of the free-stream current speed necessary for furrow erosion. In the absence of direct current measurements, such estimates are of value not only for offshore design but also for planning subsequent current measurement programs.
Numerical Simulation of Miscible and Immiscible Fluid Flows in Porous Media
Authors: Casulli V. , Greenspan D. 
Published: December 2007

Abstract
Fast, economical, and accurate finite-difference numerical methods are developed for approximating continuum models of both miscible and immiscible fluid flows in porous media. The methods apply to very general systems of equations and boundary configurations. Computer examples are described and discussed.
Simultaneous Drilling: A Radical New Method for Drilling Development Wells
Authors: Theriot Walter A. 
Published: December 2007

Introduction
Recent reports from the Soviet Union indicate that a fair degree of success is being attained with simultaneous drilling in certain fields. Although there is not a great deal of information available about the process, it is possible to determine the basic principles and some of the mechanical details involved. While any radical change in drilling methods is viewed with skepticism, only a critical evaluation can determine if it is justified or if some part of it may be made to serve our purposes.
Simultaneous drilling is a method of drilling two directional wells alternately from a single rig and using a single drilling crew. While originally used with turbodrills, it lends itself to adaption so that it may be used with rotary drilling equipment. It is not intended for wildcat drilling, but will find its widest application in development drilling, particularly from offshore platforms.
In simultaneous drilling, the two wells are drilled from the same rig, alternating the drilling from one well to the other each time a "round trip" is made. Actually, no round trips are made with this method of drilling the drill stem coming out of one hole being run down the other hole without the necessity of stacking the pipe.

Rig Design
In order to accomplish this with maximum speed and still retain simplicity in the drilling rig, the following rig is proposed. The floor of the simultaneous drilling rig is somewhat larger than that of the conventional rotary rig in order to accommodate a second rotary table and provide working space around each rotary (see Figs. 1 and 2). A single crown and traveling block assembly is used, which is shifted on a geared track by a series reversible motor between predetermined positions over each rotary as required. Two different mud systems are used with a single set of mud pumps and a manifolding system to give individual control of mud conditions in each well. Fingerboards and other auxiliary equipment are provided so that either rotary may be used for conventional drilling should the need arise. Two sets of terminal equipment are required, and certain other adaptations must be made.
Dispersive Mixing Effects on the Sloss Field Micellar System
Authors: Gupta Surendra P. 
Published: December 2007

Abstract
This paper presents results of laboratory experiments and computer simulation studies of the micellar/polymer fluids injected in the Sloss field, NE. The paper shows that the dispersion coefficient for the partitioned sulfonate in the oil phase can be an order of magnitude larger than the dispersion coefficient in the water phase. The results show that the two principal components of the micellar fluid (sulfonate and polymer) propagate at different rates because of partitioning and dispersive mixing effects. Sulfonate is produced much earlier than polymer and is concentrated in the produced oil. Sulfonate partitions into the oil phase as a consequence of ion exchange, and the polymer remains in the water phase. The oil phase that contains the partitioned sulfonate—i.e., upper-phase microemulsion—has high mobility. The increased dispersion coefficient for a component in the nonwetting phase, in this case the partitioned sulfonate into the oil phase, is supported by an independent study. These mechanisms contribute to early sulfonate breakthrough and a larger sulfonate requirement per barrel of oil displaced than anticipated for a nondispersive displacement. The results of this paper can be beneficial for design of other micellar fluids and performance predictions and interpretation of micellar floods in other fields.
An Improved Technique for Estimating Permeability, Fracture Length, and Fracture Conductivity From Pressure-Buildup Tests in Low-Permeability Gas Wells
Authors: Holditch S.A. , Lee W.J. , Gist S.R. 
Published: December 2007

Introduction
Long hydraulic fractures are usually required to optimize recovery from low-permeability gas reservoirs. Since these fractures can be quite expensive to create and since there is still a great deal of "art" associated with fracture design and creation, it is frequently helpful to use pressure-transient tests to determine created fracture properties. In this way, optimal fracture treatments can be developed for a given area. Fast et al. 1 and Kozik and Holditch presented examples showing the potential benefits of such an approach. In addition, Veatch demonstrated the effectiveness of combining the efforts of operations and research personnel to characterize and then to improve stimulation treatments in specific areas.
The specific task of the engineer is to estimate propped fracture length and effective fracture conductivity for treatments in a given geological formation, If the reasons for success or failure of previous fracture treatments can be determined, the engineer can then do a better job in the future when designing fracture treatments for the same area.
There are currently four basic techniques used to analyze postfracture pressure-transient tests:semilog (pseudoradial flow) analysis,square-root-of-time (linear flow) analysis,type-curve analysis. andreservoir simulator history matching.
The strengths and weaknesses of each technique were discussed by Lee and Holditch. No existing technique is without problems or possible ambiguity in some applications; thus, there is a need for still other techniques that may succeed in some situations for which existing techniques are inadequate.
The purpose of this paper is to introduce such a new technique for analyzing postfracture pressure-buildup tests. This technique can be particularly helpful when analyzing data from wells in which a finite-conductivity fracture has been created.

Proposed Technique
The pressure-buildup test analysis technique proposed in this paper requires that the analyst prepare a semilogarithmic graph and a square-root-of-time graph of the test data. The technique also requires use of two correction curves developed from the analytical solutions for finite-conductivity fractures presented by Cinco-Ley et al. The analyst chooses a single straight line on each of the graphs prepared for the test data and solves for fracture length, formation permeability, and fracture conductivity with an iterative procedure.

Semilogarithmic Graph
As a first step in understanding the basis for the proposed method, consider Fig. 1.
JPT
P. 981^
Influence of Fracture Heterogeneity and Wing Length on the Response of Vertically Fractured Wells
Authors: Bennett C. O , Rosato N. D. , Reynolds A. C. , Raghavan R. 
Published: December 2007

Abstract
A finite-conductivity vertical fracture intersecting a well produced at a constant rate or at a constant pressure is considered. The pressure (or rate) response is obtained from a numerical model. Two aspects of this problem are considered: (1) variable fracture conductivity and (2) unequal fracture wing lengths.
The first part of this paper examines the influence of fracture conductivity on the well response. In practice, the fracture conductivity is a decreasing function of distance from the wellbore. If the fracture conductivity decreases monotonically with distance from the wellbore, then at late times the variable fracture conductivity solutions behave like a constant-conductivity fracture, with conductivity equal to the arithmetic average of the conductivity. At early times the response is identical to that of a constant-conductivity fracture, corresponding to the highest conductivity of the fracture. For the variable fracture conductivity case, the bilinear flow period characterized by a one-quarter slope line may be obscured. Thus, analysis of short-time data can be difficult. We also consider situations where the fracture conductivity does not decrease monotonically with distance. The response for these cases is discussed in detail.
The second part of the paper examines the effect of unequal wing lengths on the pressure response. We delineate conditions under which the effect of wing length on the response will become dominant. We discuss the influence of wing length on both early- and long-time data.
Multiple Fracturing of Boreholes By Using Tailored-Pulse Loading
Authors: Swift R. P. , Kusubov A. S. 
Published: December 2007

Abstract
A laboratory experiment was developed to study the effects of pressurizing boreholes of rock samples with tailored pulses at intermediate loading rates. The experiment focused on ascertaining the loading conditions needed to initiate multiple-fracture growth from a borehole. Experiments were performed under controlled loading conditions with borehole pressures ranging from 10 to 100 MPa, loading rates from 1 to 100 MPa/ms, and pulse durations on the order of from 1 to 50 ms. The initial conditions of samples were varied to include dry, quasidry, and fully saturated states along with pressure confinement of the samples up to 50 MPa.
Observations on samples of a medium-porosity sandstone showed that the degree of multiple fracturing is quite sensitive to the condition of the borehole as well as to the loading rate and appears strongly influenced by transient pore-pressure effects. The loading rate for the onset of multiple fracturing decreased with an increase in sample water content. The influence of water was much more marked at loading rates below 30 MPa/ms than at higher rates. For loading rates above the onset, the number of fractures initiated increased with an increase in loading rate, with about 10 to 12 at a loading rate of 100 MPa/ms. The fracture threshold-breakdown pressure increased proportionately with loading rate, a dependence that is attributed to transient water-intrusion effects around the borehole. The effect of sample confinement caused the threshold-breakdown pressure to increase and noticeably lowered the loading rate for multiple-fracture onset. Only two fractures (e.g., a typical hydrofracture) occurred when water was prevented from invading the borehole region. The tailored-pulse loading tests demonstrated their viability to determine the susceptibility of various rock types to multiple fracturing at intermediate loading rates.
Unsteady Flow to a Well Produced at a Constant Pressure in a Fractured Reservoir
Authors: Ozkan E. , Ohaeri U. , Raghavan R. 
Published: December 2007

Summary
The objective of this theoretical study is to delineate the characteristics of a well producing at a constant pressure in a naturally fractured reservoir. We consider flow to a well located at the center of a closed circular reservoir. New solutions not documented previously are presented. Five flow regimes are identified and information that can be extracted from each regime is documented. Methods to determine formation parameters and to predict well deliverability are discussed.