bluuebunny/crossref_metadata_2025 huggingface dataset:
On the Subject of Reserve Estimates in Water-Drive Gas Reservoirs
Authors: Chierici G.L. , Cuieci G.M.
Published: December 2007

In his article in the JPT Forum, William Hurst resumes his discussion of our paper on reserve estimates in water-drive gas reservoirs. We can only make reference to our previous reply and add the following comments.1. The aims of our paper were:to show that the simultaneous determination of gas reserves and aquifer characteristics from the past history of waterdrive gas reservoirs can result in more than one set of solutions; andto evaluate the actual indetermination range of gas reserve estimates for some reservoirs that have a well known past history, where a water-drive had been ascertained, as they had been partially invaded by the water encroaching from edge partially invaded by the water encroaching from edge or bottom aquifers.

2. The detailed geological description of the gas reservoirs of the Po Valley, Italy, was presented in 1957 at the "Symposium on Gas Fields of Western Europe". A feature that is common to almost all of these reservoirs is their being in contact with aquifers of good permeability. 3. Contrary to William Hurst's statement that "the authors claim that they have water-drive reservoirs, but with their computer programs, they are unable to establish this effect", the presence of a water encroachment (calculated according to the van Everdingen-Hurst method) is clearly shown (Ref. 2, Table 3) in all sets of solutions presented for the reservoirs considered. The actual occurrence of a water encroachment into the reservoirs in question 2 has been proved by the following facts:a. In three of the reservoirs (BM-A, R-A, S-F)new wells have been drilled in the last few years. It has been ascertained that the water/gascontacts, at the moment the wells have been drilled, were 220 ft, 65 ft and 1 10 ft, respectively, abovetheir initial position in the three reservoirs inquestion.b. In BM-A field, 3 years after shut-down thereservoir pressure increased by 361 psi from 1,252to 1,613 psia, the initial reservoir pressure being1,927 psia.c. Some time after the production period consideredin our paper a marked deviation from linearityeventually occurred in the p/z vs Gp curve of allthe reservoirs considered. 4. Hurst's discussion seems to imply that linearity in the initial part of the p/z vs Gp curve is enough to prove a depletion-type of performance. That this does not prove a depletion-type of performance. That this does not apply has already been shown by others. There is no ground to support William Hurst's interpretation that the reservoirs in question are depletion-type and, as an unlucky consequence, to validate his "indication that considerable gas reserves may still exist" in those gas reservoirs of the Po Valley which have been abandoned. Of course, we are confident we are able to distinguish between a well needing only a work-over and a well that has been completely invaded by the encroached water (incidentally, we never wrote "logged up").

P. 561
Organization of Field Tests and Evaluation Of Tricone Bit Performance Using Statistical Analysis and Sonic Logs
Authors: Raynal Jean C. , Gstalder Serge A. , Sagot Andre M. , Muckleroy J.A.
Published: December 2007

Raynal, Jean C., SPE-AIME, Societe Nationals des Petroles d'Aquitaine Gstalder, Serge A., Societe Nationale des Petroles d'Aquitaine Sagot, Andre M., Societe Nationale des Petroles d'Aquitaine Muckleroy, J.A.,* Amoco Production Co.

The scatter of data in oilfield drilling makes evaluation of results using different bits highly uncertain. Conventional statistical theory is here applied to samples of field results to clarify and quantify evaluation, and recommendations are presented for organizing drillsite tests.

Introduction

The original text of this paper, which far exceeded the SPE's allowable length, has been condensed by the translator, using American statistical terms and drilling nomenclature. The complete original English text is on file with the SPE. For space reasons, it was necessary to omit the extensive mathematical and statistical development of the original; instead, references are given to standard textbooks where the basis of this development may be found. Although the statistical approach discussed here has been widely employed in agriculture, medicine, pharmacology, chemical analysis, pilot plant operation, and other fields in which tests are made on samples of a product or on changes produced by a cause, this approach of making statistical tests on pairs of experimental results on bits seems to have been largely neglected in drilling.

Statement of the Problem Definition of the Problem

When in drilling a well a technique or a tool is changed, it is often very difficult afterwards to answer the essential question: Did the change improve the result, or make it worse? Drilling results may be essentially shown in three ways:as footage drilled per hour;as footage drilled per bit; andas the cost per foot drilled, which incorporates the preceding two and is the most important result.

The difficulties in judging these results are many and varied, but they always manifest themselves in a loss of time and so of money. If we wish the drilling tests to be proved absolutely, they must be repeated many times; if, on the other hand, we jump to a hasty conclusion, the result can be a bad decision. Either route is costly.

Analysis of the Problem

There are many variables in drilling, of which the most important are the following:

Weight on bit (W) Diameter of bit (D) Type of bitWear on bit when pulled Revolutions per minute (rpm) Flow rate of drilling fluid (Q) Nature and properties of drilling fluid Pressure difference across rock surface ( p) Depth Rock properties

Most of these are poorly measured. For the same drilling rig, drilling the same well, it is relatively easy to maintain constant values of W, rpm, and Q.

JPT

P. 506
Coiled Tubing as Initial Production Tubing: An Overview of Case Histories
Authors: Nirider H.L. , Snider P.M. , Walsh K.D. , Cordera J.R. , Williams Joe
Published: December 2007

From Jan. 1993 through Feb. 1995 Marathon Oil Co. completed 23 newly drilled gas wells with coiled tubing as the initial production string. This paper reviews operational aspects of representative jobs, summarizes areas where improvements in equipment and technique were implemented, and addresses cost and productivity benefits of rigless completions. A summary of lessons learned is also included.

Introduction

Marathon has used coiled tubing for initial production tubing in several wells to match the tubing to the well productivity, to unload fracture fluids as quickly as possible, and to minimize cost by reducing the time the drilling rig stays on location. Use of coiled tubing allows tubing size to be matched closely to the performance of relatively low rate wells, minimizing the tubular costs and improving the well's ability to stay unloaded. In areas with water-sensitive formations, live-well completion prevents formation damage associated with kill fluids.

The main areas of improvement from one job to the next involved the use of a pressurized, hydraulically operated access window, ensuring that all fracture sand was cleaned out before landing the coiled tubing and using a "hot-cutoff' system to make the final cut on the coil tubing. An additional benefit is that no fluid is lost to the formation during the completion.

Lessons learned include keeping the coiled-tubing size large enough to run smaller coiled tubing through it for cleanout and slickline work, care in closing blowout preventer (BOP) rams to avoid damaging the coiled tubing, and the use of wellhead equipment specifically designed for use with coiled tubing. This technique is especially suited to low pressure and water-sensitive reservoirs where fluid loss is a concern. An additional benefit is the cost savings from reducing the hole and casing sizes to match the reservoir potential. In addition, this completion technique is often quicker than using a conventional completion rig and jointed tubing.
An Evaluation of Concentric Casing for Nonuniform Load Applications
Authors: Pattillo P. D. , Moschovidis Z. A. , Lai Manohar
Published: December 2007

This study offers both theoretical and experimental evidence of the benefits of running a concentric casing configuration in a nonuniform load environment. The study is further enhanced by numerical modeling, particularly with regard to determining the sensitivity of the configuration to key variables. The alternative of running a single string of heavy-wall casing also is discussed.
Integrated Management Of Multiple Reservoir Field Developments
Authors: Lyons S.L. , Chan H.M. , Harper J.L. , Boyett B.A. , Dowson P.R. , Bette S.
Published: December 2007

This paper describes the coupling of a pipeline network model to a reservoir simulator and its application to optimize the production strategy of two Mobil field developments. Mobil's PEGASUS simulator is an integrated, all-purpose reservoir simulator that handles black-oil, compositional, faulted, and naturally fractured reservoirs. We have extended the simulator to allow simultaneous modeling of multiple reservoirs coupled with surface pipeline networks and processes. This allows us to account for the effects of geology, well placement, and surface production facilities on well deliverability in a fully integrated fashion. We have also developed a gas-contract allocation system that takes the user-specified constraints, target rates, and swing factors and automatically assigns rates to the individual wells of each reservoir. This algorithm calculates the overall deliverability and automatically reduces the user-specified target rates to meet the deliverability constraints. The algorithm and solution technique are described.

This enhanced simulator has been applied to model a Mobil field development in the Southern gas basin offshore the U.K., which consists of three separate gas reservoirs connected by means of a pipeline network. The simulator allowed us to determine accurately the effect of varying the development timing of these reservoirs on individual reservoir and total field performance. Several development scenarios are shown to illustrate the capabilities of PEGASUS.

Another application of this technology is in our field developments in North Sumatra, Indonesia. Here the objective is to optimize the development of multiple fields economically to feed the P.T. Arun liquid natural gas (LNG) facility. A range of gas compositions, well productivities, and facilities constraints are considered in an integrated fashion, resulting in improved management of these assets. Model specifics are discussed.

Introduction

Optimal exploitation of oil and gas fields requires an integrated approach. Several reservoirs in a field development typically compete for limited surface production capacity. Typically, as fields mature, the development of additional satellite reservoirs increases the competition for capacity in the surface facilities. This is especially true in expensive offshore projects. Historically, engineers have used reservoir simulators to develop an exploitation scheme for a given hydrocarbon reservoir. This approach optimizes the development of a single reservoir but neglects the total effect on surface-capacity limits from other reservoirs sharing the same surface facilities.
Plugging Off Water in Fractured Formations
Authors: Howard George C. , Scott P.P.
Published: December 2007

A field remedial procedure utilizing a kerosene-cement slurry as a water plug-off agent in fractured formations was evaluated both in the laboratory and in the field. This procedure has proved to be capable of effectively shutting off water without causing permanent impairment of the oil production. Success was attributed to the fact that an immobile cement slurry, when placed in a water-producing strata, will set and form an impermeable barrier; whereas when placed in an oil-producing section the cement will retain a relatively high permeability and may be removed by acidizing.

Introduction

One of the most perplexing problems facing the oil industry is the selective exclusion of water production from oil or gas-producing wells. This problem has been studied by many investigators in an attempt to develop a material that is not only capable of reducing water production but is also capable of being selective in that it will not impair oil production in either fractured or intergranular type reservoirs. A study of these two types of formations indicated that two distinct types of materials for controlling water production might be required - a completely liquid plugging agent for intergranular formations and a semi-liquid or slurry type plugging agent for fractured formations. This paper is limited to the control of water production from fractured formations.

A common source of water in the vicinity of oil bearing rock reservoirs is water which previously has entered and, because of its higher density, generally lies near the bottom of the formation. When the deepest point of penetration of a well into such an oil and water-bearing formation is above the level of the water, and the dynamical gradients due to the flow of oil overbalance the difference in densities between oil and water, water production becomes a problem. Then the water level rises in the shape of a cone and is produced from the lower depths.
Technology Transfer Through Integrated Production-Engineering Software
Authors: Zhu Ding , Wu Gary , Hill A. D. , Economides M. J.
Published: December 2007

Just as the hand-held calculator revolutionized the capabilities of engineers 20 years ago, the desk top computer is revolutionizing technology transfer in engineering practice today. For example, more than 10,000 independent oil/gas producers in the U.S., most of whom have difficulty gaining access to the most updated technology, rely on personal computers (PC's) to keep up with the explosion of information and engineering-process developments.
Sensitivity Analysis Applied to a Steady-State Model of Natural Gas Transportation Systems
Authors: Stoner Michael A.
Published: December 2007

A nodal formulation for the mathematical model of a gas transportation system is presented and the Newton-Raphson method is proposed as a means of solving the resulting nonlinear equations. Once a solution has been obtained, a linearized form of the model can be used to assess the sensitivity or interaction of system variables. The equations necessary to perform this sensitivity analysis are developed and demonstrated on a sample system. A scheme for performing Gaussian elimination on a general set of simultaneous linear equations having a sparse coefficient matrix is presented.

Introduction

This paper espouses the use of a nodal formulation for the steady-state model of a gas transportation system and attempts to show how sensitivity analysis applied to this model can be used to aid in the design and operation of the prototype systems. the mathematical model used here has been described in a previous paper, which was based on earlier work. The basic model is recapped here. Solutions of this model are obtained using the n-dimensional Newton-Raphson (N-R) technique with an acceleration scheme, the main purpose of which is to prohibit divergence. The N-R method requires the solution of a set of simultaneous linear equations whose coefficient matrix for this application is very sparse. In preparing digital computer programs using this model, this sparsity has been exploited to great advantage in core storage savings and execution time efficiency. The basic aspects of a sparse matrix solution scheme for a general set of simultaneous linear equations and rudimentary programming steps are covered in the Appendix.

Once a solution has been obtained for the model, the user often poses questions such as, "How different would the solution be if I had specified a different value for this load?" Or "How much more horsepower would be needed here if we had increased this pressure 15 psi? The user could make the specified changes and resolve his model to obtain the answers. However, if he is willing to accept approximate answers to these questions, then an appropriately executed sensitivity analysis can provide the answers with considerable saving in computer time and associated expense. The development of the equations necessary to perform a general sensitivity analysis using the proposed model is presented. Computational shortcuts using the sparse matrix solution of a set of simultaneous linear equations are demonstrated. Finally, an example is hypothesized to demonstrate one way of using the proposed sensitivity analysis scheme.
Extending Rod-Pump Life During Proppant Flowback at the Lost Hills Field
Authors: Roberts I. G.
Published: December 2007

Proppant flowback from hydraulically fractured wells can lead to sand wear on the pump barrel and plunger and to increased pulling costs on rod-pumped wells. Two separate approaches for lengthening the run times of the pumps were tried and evaluated individually. One approach was to install pumps that allow production of a sand-laden fluid. Pressure-actuated plunger (PAP) pumps were field tested, and they showed an average increase of 81.6% in run time. These split ring wiper pumps clean the barrel of sand before the passing of the plunger. The other approach was to keep the sand from entering the pumps. When downhole filters were used, the run life of the pumps with the filters increases 135%. Well-pulling cost savings of U.S. $11.91 per well day and U.S. $9.24 per well day are documented for the PAP pumps and filters, respectively. Application guidelines based on the sand-loading rate and gross liquid production of the wells are presented, as well as some operational experiences.
Development of the HT-BP Neural Network System for the Identification of a Well-Test Interpretation Model
Authors: Sung Wonmo , Yoo Inhang , Ra Seunghoon , Park Heungjun
Published: December 2007

The back propagation (BP) neural network approach has been the subject of recent focus because it can identify models for incomplete or distorted data without performing data preparation procedures. However, this approach uses only partial sets of data to reduce computing time and memory, and it may miss the points representing characteristics of the curve shape. Therefore, the resulted model may not be correct, forcing one to use sequential neural nets to find the correct model.

We present the Hough Transform (HT) method combined with the BP neural network to improve this problem. With the aid of an HT, we can extract one simple pattern, including noisy and extraneous points, from the full-set data. A number of exercises also have been conducted for the published well-test data with the artificial intelligence neural network identification system (ANNIS) we developed. The results show that ANNIS is quite reliable, especially for the incomplete or distorted data. They also demonstrate that the modified Levenberg-Marquart interpretation model, also developed in this work, successfully estimates reservoir parameters.
Time Delayed and Low-impairment Fluid-loss Control using a Succinoglycan Biopolymer with an Internal Acid Breaker
Authors: Bouts Marcel N. , Trompert Ruud A. , Samuel Alan J.
Published: December 2007

The formation damage that results from the incomplete back-production of viscous, fluid-loss control pills can be minimised if a slow acting internal breaker is employed. In particular, core-flow tests have indicated that combining a succinoglycan-based pill with a hydrochloric acid internal breaker enables a fluid-loss system with sustained control followed by delayed breakback and creates only low levels of impairment To describe the delayed breaking of the succinoglycan/hydrochloric acid system, a model, based on bond breaking rate, has been used. With this model, it is possible to predict the change of the rheological properties of the polymer as a function of time for various formation temperatures, transition temperatures of the succinoglycan and acid concentrations. Hence, the model can be used to identify optimum formulations of succinoglycan and acid breaker on the basis of field requirements, such as the time interval over which fluid-loss control is needed, the overbalance a pill should be able to withstand and the brine density required.
Hydrofluoric Acid Reaction with a Porous Sandstone
Authors: Williams B.B. , Whiteley M.E.
Published: December 2007

A procedure is developed for predicting changes in the porosity distribution in a sandstone resulting from reaction with hydrofluoric acid. This procedure is based on a theory for slow heterogeneous reactions in a porous solid where the solid matrix is consumed in the reaction Process. Reaction-rate data for use in this theory are obtained from experiments where acid is injected through short cores and effluent concentration measured using a fluoride specific ion electrode. This rate is found to be first order in hydrofluoric acid concentration. Variations in rate with temperature and quantity of rock dissolved are shown.

Introduction

Mixtures of hydrofluoric and hydrochloric acid are used to stimulate gas and oil production from sandstone reservoirs by increasing formation porosity and permeability near the wellbore. This porosity and permeability near the wellbore. This acid will react with almost all constituents of naturally occurring sandstones, such as silica, feldspar, clays, and calcareous material. In order to utilize this acid effectively, it is necessary to predict where acid reacts and changes that occur predict where acid reacts and changes that occur with reaction.

Chemical reactions between hydrofluoric acid and silica or calcite in the rock matrix are simple, well known reactions. However, reactions with silicates such as clays or feldspars are complex since these minerals occur as three-dimensional lattices with only average empirical formulas. Examples are kaolinite ([A Fe +3 Mg]-Si O1.8 0.1 0.1 2 5 [OH]. Ca), montmorillonite (A Mg Si4 0.05 1.67 0.33 4 O [OH] . NA), and feldspars such as albite10 2 0.33 ([NaSi A ]). In the reactions shown below the3 8 reaction of sodium silicate is used to represent hydrofluoric acid reaction with silicates found in the matrix.
Waterflood Geochemical Modeling and a Prudhoe Bay Zone 4 Case Study
Authors: Li Ying-Hsiao , Crane Steven D. , Scott E. Mark , Braden John C. , Lelland W. Greg Mc
Published: December 2007

Scale formation during waterfloods can damage reservoirs far beyond the wellbore region. A comprehensive analysis with geochemical modeling can improve waterflood design in the selection and/or mixing of source waters and thus, mitigate formation damage arising from injecting incompatible fluids. The method also predict the types of scales and their severity at various production stages. This will help optimize treatment schedules and reduce operation costs.

In the case study of Zone 4, Prudhoe Bay Unit (North Slope, Alaska), the geochemical model was validated with the laboratory analyses of Zone 4 produced water samples. Then it was used to evaluate the impact of mixing formation brine and seawater on rock-fluid interactions and scale formation. The prediction is consistent with the observation of calcite formation in early production at Prudhoe Bay. The model also predicts the precipitation of iron carbonate and iron sulfide scales as the seawater flood continues.
Turbulent Dispersion in Porous Materials as Modeled by a Mixing Cell with Stagnant Zone
Authors: Kyle C.R. , Perrine R.L.
Published: December 2007

This paper reports on a simple theoretical analysis of dispersion in rapid flow through porous materials, giving a comparison of predicted results with experiments. The analytical model considers a pore structure which acts like a sequence of mixing cells, each coupled with a stagnant zone.

Computed results compare very favorably with experimental observations on flow through a staggered matrix of cylinders. This, in turn, has been shown to behave the packed beds of spheres with corresponding properties. Agreement requires that values for certain theoretical parameters be fitted from the data The values required for these parameters are very reasonable. Development of parameters are very reasonable. Development of this approach could be useful for a number of related problems.

Introduction

The dispersion of two dynamically similar miscible liquids in laminar or turbulent flow through a porous material is a very complex process. However, it can be broken down into four process. However, it can be broken down into four basic mixing mechanisms:

(1) Molecular diffusion. Where the flow velocity is appreciable, or pore size is larger, diffusion is usually negligible. Molecular diffusion will not be discussed in this paper.

(2) Uneven fluid movement due to irregular pore geometry and inhomogeneities in the media. Both of these factors are difficult to treat, and are usually neglected in theoretical analysis.

(3) Uneven fluid movement due to velocity differences within the pores and passages. The zero-velocity boundary condition on each solid surface assures this type of mixing in both laminar and turbulent flow.

(4) Mixing by rotational flow, or by turbulent eddies within the pores or passages.

The last two are both convective mixing processes and depend primarily upon the level of processes and depend primarily upon the level of energy dissipation in the media, as well as on the geometry of the system. In general as the velocity increases and the friction losses rise, so does the efficiency of the mixing process.

Dispersion has been reviewed thoroughly by Perkins and Johnston and has been studied Perkins and Johnston and has been studied extensively by others.
A Method for Determining the Static Pressure of a Well from Buildup Data
Authors: Odeh A.S. , Al-Hussainy R.
Published: December 2007

The method described here for determining the static pressure of a well from the buildup test data differs from the commonly used methods in that it does not require the knowledge of the porosity, permeability, viscosity, compressibility, and the drainage area. It permeability, viscosity, compressibility, and the drainage area. It does, however, require the value of the pressure at time zero.

Introduction

In a buildup analysis, the buildup pressure, Psw, is

plotted vs on a semilog plot. A straight line plotted vs on a semilog plot. A straight line is obtained from whose slope kh/ is calculated.

Extension of the straight line to = 1 gives a

p*. If the boundary effect has not been felt during p*. If the boundary effect has not been felt during the production period prior to the buildup test, then p* ps, the static pressure of the well. On the other p* ps, the static pressure of the well. On the other hand, if the well has been producing for a considerable period of time so that the boundary influences the period of time so that the boundary influences the behavior of the system, then the p* value must be corrected to obtain ps. A method is derived that relates p* to ps. The method differs from the commonly used ones in that it does not require the knowledge of porosity, permeability, viscosity, compressibility, and drainage area. However, it does require the value of pressure at time zero. The derivation follows.

Derivation and Analysis

From a Horner-type plot for a hounded reservoir

The average static pressure ps is related to the extrapolated pressure p* by the Matthews-Brons-Hazebroek pressure correction function pressure correction function

From the material balance equation,

where pi is the initial pressure prior to withdrawing a volume qtp of fluid. Also, pi can be considered any accurage stastic pressure with a corresponding production time. production time. Eq. 3 is written as

(4) 2 .303 (pi - ps) = t DA , 4 m

where m, the negative of the slope of the buildup, is2.303 q equal to .4 kh

Substituting Eq. 4 in Eq. 2 gives

JPT

P. 621
Optimum Flow Conditions Through Tubing and Annular Spaces
Authors: Garaicochea F.
Published: December 2007

Several charts similar to Fig. 1 were presented in Refs. 1 and 2. These charts represent solutions for obtaining the pressure drop in tubing and annular spaces for various flow conditions. It can be seen that there is a value of q M for which the density curves of the well fluid show a minimum pressure gradient dp/dh. From the charts presented in the referenced papers, the q M values that provide the minimum pressure gradients were selected and are shown in Table 1.

The values of Table 1 can be described by straight lines whose equations are:

.............................(1)..................(2)

Replacing M with its equivalent,

.......................(3)

................(4)

Fig. 2 was prepared to simplify the solution of these equations for the special case where gamma = 0.70 and gamma = 1. 10. In this nomograph, f is defined as

This nomographic solution provides a fast means of diagnosing flow conditions in wells and in sizing tubing.

TABLE 1-MASS FLOW RATES THROUGH TUBING ANDANNULAR SPACES THAT RESULT IN MINIMUMPRESSURE GRADIENTS

Flow Through Tubing Annular FlowqvpM d qopM (do-di) 135,000 1.995 500,000 2.776 170,000 2.441 610,000 3.401 200,000 3.068 700,000 3.901

P. 447
Use of Irregular Grid in Reservoir Simulation
Authors: Settari A. , Aziz Khalid
Published: December 2007

In this paper three different schemes for the finite-difference approximation of ( ) terms with irregular spacings of the grid points are investigated. Several methods of selecting the grid spacing are considered, and numerical results are presented for some carefully selected examples. presented for some carefully selected examples. Results indicate that one of the most commonly used finite-difference schemes may unnecessarily result in large discretization errors; the other two schemes discussed result in greater accuracy and are no more difficult to use.

Introduction

Finite-difference methods are used widely for solving partial-differential equations encountered in petroleum reservoir simulation. In many practical problems it is necessary to refine the grid in certain problems it is necessary to refine the grid in certain parts of the reservoir, thus resulting in an irregular parts of the reservoir, thus resulting in an irregular grid spacing for the system. For example, the local refinement of grid is usually necessary in the study of the flow behavior near a well, i.e., the case of coning problems. On the other hand, it is usually advantageous to make the grid locally coarse over aquifers and large gas caps. In spite of the importance of irregular grids in reservoir simulation and other engineering problems, little is known about the effect of various schemes on the over-all discretization error. Most literature on the subject of irregular grid spacings is concerned with the treatment of irregular boundaries. Here, the properties of several difference approximations to properties of several difference approximations to the second-order operator Au = [ ] are investigated. Operator A is encountered in all diffusion-type equations, such as multiphase flow in porous media and heat conduction with temperature-dependent conductivity. For simplicity, we limit our study to one space variable in this study. All results reported here can be extended readily to any number of space variables.
Contained Injection Pattern and High Pumping Rates Solve Permeability Problems in a North Texas Caddo Conglomerate Water Flood
Authors: Swan C.R. , Riley E.A.
Published: December 2007

To effect any successful waterflood operation, it is essential to first recognize the problems to be confronted and then to properly apply basic techniques to solve them. In the case of the Rusmag field the major problem was the highly varying permeability profile native to the Caddo conglomerate reservoir. The operator has apparently controlled this problem, as evidenced by 2.5 years of successful performance under waterflood operations.

Although there currently are four separate flood efforts being conducted in the Rusmag field, this paper is concerned chiefly with presenting a case history of the Rusmag Unit waterflood. The Unit contains the major portion of the reservoir, and 2,500 of the approximately 4,000 acres in it currently under flood, with the remaining acreage scheduled for development in 1962.

Unit oil production is near 2,000 B/D, with water-injection rates averaging 400 B/D at pressures ranging from 0 to 550 psi. Cumulative waterflood oil recovery to Jan. 1, 1962, has been 573,765 bbl, with an ultimate recovery of 2 million bbl of oil possible.

JPT

P. 1104^
The Significance of Time-Dependent Transports in Storm-Generated Coastal Currents
Authors: Goldman Joseph L.
Published: December 2007

The terms in the equations of motion that represent the transport due to storms are tested, and the resulting currents are considered for the case of a storm over deep ocean. By, using time-dependent functions to generate the ocean transport, we allow for the steady-state flow to be examined. When the effect of a shoaling bottom near shore is considered, the contribution of the time-dependent transport is negligible, whereas the advective terms become important.

Considering a storm with a constant speed in a specified direction, we derive the continuity equation for the generation of currents and find that, for a stationary system, equations are not consistent for a steady-state solution except for very special cases. One such special case would be when the storm is over an ocean with a flat bottom.

For nonstationary cases, when the same equations are applied with the assumption of zero bottom stress and of a balance of flux inward and outward from the shore, a number of balance relationships are revealed.

For the current in the longshore direction, the "geostrophic" transport is balanced by stress, and the first term in the relation with the steady-state assumption, defined as the curl of the stress is equal to the divergence of the flux.

The conclusions from this analysis and other cases indicate that nothing is to be gained by having a time-dependent transport that moves with a storm as a contributing term to coastal currents and storm tide. Wind building up transport at shore is so large that there is only an insignificant correction from deep-water transports.

Introduction

The dynamic problem of wind transmitting its energy to water and driving the water has been considered theoretically for deep water and the so-called "infinite ocean". Near-shore processes near the shallow continental shelves with bottoms of variable slope complicate the problem and some consideration has been given to them.

In the past, knowledge of the profile of storm generated currents was dependent on sparse measurements of current usually made during safe, quiescent periods that are interpolated in space and then extrapolated in magnitude to represent storm conditions. The purpose of the development presented here is to enhance future extrapolation by insuring that it is done with dynamic consistency.

To keep from having to treat all the terms in the equations describing the storm-generated current, the importance of each of the terms as they apply in general and to specific cases has been investigated. This has been done through numerical solutions to the equations of motion, using computer programs that generate currents for particular programs that generate currents for particular locations (with distinctive bottom topographies and coastline orientations and through theoretical analysis.
Environmental Aspects of Oil Producing Operations- Long Beach, California
Authors: Allen D.R.
Published: December 2007

Introduction

Environment, Ecology, Pollution - these were called the "bywords of today" by William H. Curry, AAPG president, early in 1971. Others have termed the 1970's as the decade, that will be remembered for the surge of public consciousness for our environment. It is unlikely that any other industry has been affected more by this tide of public thought than the oil industry. Other industries are commonly tied to one aspect or problem area such as noise or air pollution, but the many facets of the oil business make it vulnerable to attack from all sides. It has been said that there is no force so strong as an idea whose time has come. It is rather obvious that the time for environmental awareness is here now. Almost any industrial complex has some noise, air, water, or visual pollution problem. However, the oil business is beset by one additional problem: oil is where you find it, and a producing operation cannot be moved to an area zoned for heavy industry. Therefore, the industry must go a step further in public relations and environmental controls.

The problems of producing oil in an urban environment appear to have been extended by some as far as the North Slope. The City of Long Beach does not have a North Slope operation, but it is hoped that our experience in a visible and very sensitive location will be helpful to the industry as a guide to future operations.
A Data Gathering and Processing System To Optimize Producing Operations
Authors: Bucaram S.M.
Published: December 2007

This computerized system, which collects, processes, and stores data on and analyzes and reports the performance of production equipment and operations, is one step closer to the optimum profitability of producing properties. It is designed primarily to be used by the production man properties. It is designed primarily to be used by the production man directly responsible for day-to-day economic decisions.

Introduction

In any attempt at optimizing operations by means, for example, of a failure-control program, basic information is required for defining the nature and magnitude of the problems involved and for estimating the economic stakes. The information determines whether or not one should try to solve a particular problem; and if more than one solution is possible, it aids in deciding on the most profitable one. In short, the basic information makes it possible to set economic priorities to the solution of problems. Methods of obtaining basic information related to equipment performance have been the subject of much work. Many oil-producing companies have created and now operate data gathering and processing systems, all of which have two things in common:

they obtain accurate and timely information and process and condense it into an easily usable and process and condense it into an easily usable and digestible form; and they use computers to process and report data.

Atlantic Richfield has created a system for data gathering and handling that has been in use throughout its Continental U. S. and Canadian operations since late 1969. This system, known as the Equipment Performance Reporting System, relies heavily on the use of computers. It was developed as a cooperative effort with field personnel to the point that it is now part of the Company procedures. By late 1971 the system had more than 34,000 records in its data banks. Since its inception, the original concept of a data gathering and processing system for use by production personnel has been expanded according to needs production personnel has been expanded according to needs discovered as a result of using the system. These needs are:

(1) to set better specifications for subsurface and surface equipment, (2) to predict future performance of equipment, and (3) to follow closely performance of equipment, and (3) to follow closely the economic impact of remedial action such as area-wide corrosion treating programs.

The Equipment Performance Report System-Part One

The Equipment Performance Report System consists of four parts. The following discussion will be limited to Part One, which is concerned with subsurface failures, and to Part Three, which handles well inhibition. Parts Two and Four will be described later. As early as 1964, Fincher and Nunn defined a usable data gathering and processing system as one that contains1. A simple report form,2. Complete data about each reported event,3. Computer processing for rapid data handling, and4. Output in the form of orderly and concise data summaries for easy review.

JPT

p. 185
A Magnetic Susceptibility Method for the Determination of Liquid Saturation in Porous Materials
Authors: Whalen J.W.
Published: December 2007

The design, operation and evaluation of an instrumental method for the determination of fluid saturation in porous materials during multiphase flow studies is described. The presence of a magnetic tracer comprising approximately 20 per cent by weight of the aqueous phase is necessary in the utilization of this method.

The results of two-phase relative permeability studies on two samples of porous media are presented. The realizable accuracy of the magnetic susceptibility apparatus in fluid saturation determination is estimated to be 2 saturation per cent. The response characteristics of the instrument, together with its simplicity of operation and maintenance are sufficient to recommend its use in routine laboratory studies.

Introduction

The problem of fluid saturation determination in laboratory multiphase flow studies characterizing oil recovery processes is one which has been given exhaustive study. Briefly the requirements which are considered essential for a method serving this purpose are:that the measurement be made external to the porous rock sample under study with no interruption of the fluid flow pattern,the saturation indication must be independent of fluid distribution in the volume scanned by the measuring device,the sensing element should have a small field of definition enabling several independent measurements to be made along the length of a core sample, andthe properties of the fluid phases should not be too greatly influenced by required tracer substances.

Several methods of saturation determination have found acceptance as meeting most of the above requirements. These include resistivity, X-Ray absorption, radiotracers, and neutron diffraction. The merits of these techniques have been discussed elsewhere in detail and will not be considered here. It may, however, be pointed out that the elaborate instrumentation required by the methods mentioned above, with the exception of the resistivity method (which is undesirable from other standpoints) encourages the development of methods of saturation determination which, while meeting the requirements listed, are simple to operate and maintain.

It is the purpose of this paper to describe the instrumentation and evaluation of a technique for the determination of fluid saturation which combines relative simplicity with an accuracy and applicability comparable with methods now in practice.
Use of Radioactive Iodine as a Tracer in Water-Flooding Operations
Authors: Watkins J. Wade , Mardock E.S.
Published: December 2007

The accurate evaluation of reservoir-performance characteristics in the secondary recovery of petroleum by water flooding requires use of a water tracer that may be injected into water-input wells and detected at oil-production wells to supplement data obtained from core analyses, wellhead tests, and subsurface measurements. Radioactive iodine has been used successfully as a water tracer in field tests to determine:relative rates and patterns of flow of injected water between water-input and oil-production wells andzones of excessive water entry into oil-production wells.

Laboratory evaluations of potential water tracers, previous tracer studies, the value of using a radioactive tracer, general field procedures, and the use of surface and subsurface instruments for the detection of the emitted gamma radiation, are summarized. Data from the field tests are presented graphically and discussed in detail.

It is concluded that the radioactive-tracer method, using radioactive iodine, may be used successfully to measure either the relative rates and patterns of flow or zones of excessive water entry into wells under conditions of comparatively rapid transit time between wells.

Introduction

Extensive use is made of data obtained from core analyses, wellhead tests, fluid characteristics, and subsurface measurements in evaluating the sweep efficiency of water injected into oil sands for the recovery of oil. Theoretical flow rates and patterns may be calculated from those data using radial-flow formulas, if it is assumed that the physical conditions in the productive formation are homogeneous. Unfortunately, homogeneous conditions rarely, if ever, exist in oil-productive formations. The use of a tracer that may be injected into an oil sand and detected quantitatively, or even qualitatively, at offsetting oil-production wells provides basic data that may be used in determining more accurately the subsurface rates and patterns of flow of injected water between wells than is possible by theoretical calculations based on assumed conditions. Consideration of the data obtained by using a water tracer assists in the application of remedial measures to water-input wells, such as plugging of channels, or selective plugging of highly permeable zones, thereby effecting a more uniform flood and a greater ultimate oil recovery.
Sand Production Determined from Noise Measurements
Authors: Stein Nathan , Kelly John , Baldwin W.F. , McNeely W.E.
Published: December 2007

A method has been developed for using a logging tool in wells with sand problems to develop information on (1) producing rates above which sand production occurs, (2) the location of the sand-producing interval in a zone, and (3) the flow rate contributions of various segments of a perforated interval.

Introduction

In any area subject to sand production problems, it is desirable to know what production rate will precipitate sand movement and at what formation depth precipitate sand movement and at what formation depth the sand is being produced. These questions are particularly important in multiple-completion gas particularly important in multiple-completion gas wells in which produced sand from an upper formation can strike the tubing that reaches to the lower formation. Tubing failure often occurs in such blast zones unless some preventive measure is taken, such as (1) using blast-resistant material in the tubing string, (2) using some form of sand control, or (3) restricting production rate. Knowledge of the sand-producing tendencies of the formation can be helpful in applying any of these measures.

Theoretical Considerations

Produced fluids striking tubing will generate noise. Produced fluids striking tubing will generate noise. Sand carried in fluid moving at a given velocity will contribute additional noise. A well log can be made that reflects generated noise per unit of time recorded as a function of production rate and depth.

Relation Between Total Noise and Production Rate

We assume that the generated noise is proportional to the kinetic energy of the materials produced into the wellbore per unit of time. Then(1) However,

(2)

and

(3)

Substituting Eqs. 2 and 3 into Eq. 1 gives

(4)

For a given toad productive interval in a well, A and L can be included with the other constants in a new constant, C2. Thus,(5)

Taking the logarithm of the terms on each side of Eq. 5, then taking the derivative of each term with respect to log q, gives(6)

Eq. 6 can be used to define the fluid production rate at which sand production begins. A plot of thei logarithm of Nd vs the logarithm of q for ad=1 single-phase fluid at two levels of q results in a straight line with a slope of 3 if no sand is produced.

JPT

P. 803
Design and Evaluation of Gravel and Frac Packs With a Fully Three-Dimensional Wellbore Simulator
Authors: Klein H. Hank , Cooper Gary D. , Nelson Steven G.
Published: December 2007

During the gravel packing and fracturing processes in deviated wells the flows can follow complicated three-dimensional paths in the treating string. In this paper we present the formulation of a three-dimensional numerical model of fluid and solids transport for evaluation and design of these completion events. The simulator tracks the slurry flow from the surface, throughout the wellbore, and into the perforations. It treats fluid return and loss into the formation. The model simulates fluid displacement, gravel settling, dune formation, bridging, fluid flow through packed solids and flow into and out of screens.

We present validation results against laboratory and field data for various fluids, deviations, pumping rates, and solids loading.