bluuebunny/crossref_metadata_2025 huggingface dataset:
Matrix Acidizing Horizontal Gravel-Packed Wells for Fines Damage Removal
Authors: Stanley F. O. , Troncoso J. C. , Martin A. N. , Jamil Omar Ali
Published: December 2007

It’s a fact of life – many gravel packs plug up. As time passes, skin factors go up and production rates go down. Much of the money that was spent on creating a sand control completion with minimum skin may eventually count for nothing. In order to prolong the effectiveness of the gravel pack (GP) and as a added benefit reduce the need for workovers, a method was developed in the Far East to remove these fines and dramatically reduce the skin factor. The method employs relatively small volumes of a specialized HF (hydrogen fluoride) acid system, designed to penetrate into the GP and very near wellbore area. The HF acid system uses an organo-phosphonate (HV) acid to control the production of HF and to control and drastically reduce potentially damaging secondary and tertiary precipitates. The system will be referred to as HV:HF Acid in this paper.

This HV:HF Acid system can be applied to any well with a screen and/or GP that has damage caused by the migration of formation fines and/or drilling mud particles. It is not limited by the type of screen or gravel nor by the length or number of sets of screens. The method has potentially enormous implications throughout the world. Any well with a GP or screen could potentially benefit from this method of treatment, including long horizontal intervals, which up to now have been very expensive to treat, due to the larger volumes of acid normally recommended.

The results of this HV:HF Acid method will be illustrated by 3 case histories from the Far East, including horizontal wells. The observations from these treatments allow us to conclude that this method is highly successful, cost effective, and applicable to a broad spectrum of well conditions. The reduced stimulation volumes provide better economics, so that even long sections and horizontal wells can now be stimulated at reasonable costs.
Controlling Inclination in Rotary Mode in Tight TVD Corridors using a 2-Dimensional Steerable System
Authors: Rasheed W.
Published: December 2007

This paper is a review of a 2D Rotary Steerable System as used to control the inclination of over 200 horizontal wells. Horizontal well drilling is a common directional drilling technique enabling access to hydrocarbon reserves whilst lowering field development costs and improving well production. In order to maximise drilling in the "filet mignon" of the reservoir, geologists often require tight TVD corridors to be maintained. To achieve this, TVD corrections can be made in either rotary or oriented mode. Both methods are evaluated in terms of their effectiveness and efficiency. Factors in favour of a 2D Rotary Steerable System are: it is reliable, proven and adds significant value to the drilling process. It is effective because it enables tight TVD objectives to be met. It is efficient because it increases Rates of Penetration (ROP) whilst improving well-bore quality. These benefits are direct consequences of eliminating oriented inclination control, the smoothing out of well-bore curvature (dogleg severity) and the continuous mechanical agitation of cuttings beds. Considerable offset data (Ref 1 to 7 inc) shows how directional drillers have used rotary BHA’s to meet tight TVD objectives; much to the satisfaction of Geologists.
The Use of Brine as an Injection Fluid to Reduce Disposal Cost and Increase Gas Production
Authors: Schneider Barry , Freeman David
Published: December 2007

A major concern of any hydrocarbon producer is the production of brine. Since the brine is potentially environmentally hazardous certain legal guidelines for its disposal must be followed. The current process is to inject it into an empty reservoir. However, the problem of increasing cost has made this option undesirable. A possible alternative to this process is to use the brine as an injection fluid into the same active reservoir from which it was produced. The benefits from doing this are two-fold. The cost of brine disposal is reduced or eliminated and the reservoir will under go volumetric sweeping creating an increase in gas and oil production. The potential of decreasing the net production costs is important to the local producers in determining the economic feasibility of new projects.

This study includes a sample set of data that shows the level of production increase that could be expected from brine injection into a gas-condensate reservoir located in the Rose Run formation, a producing zone found throughout the Appalachian Basin. Due to the nature of a gas-condensate reservoir, the pressure increase or pressure maintenance that would be developed in the reservoir will cause the amount of gas produced to increase as well as the associated light oils. The results, calculated through application of the material balance equation of injecting 10 STB/d of brine into the reservoir shows an increase in cumulative gas recovery of 0.35%. Also included for review are the legal issues which apply to the injection of brine in the state of Ohio.
New Environmentally Safe Heat Transfer Fluid Improves The Performance of Heaters in Gas Production and Transmission Systems
Authors: Hallman John H. , Acor Lori G.
Published: December 2007

Indirect line heaters are used in gas production, storage, and transmission systems to boost gas temperature in order to facilitate transmission efficiency and reduce problems from water condensation and hydrates. Heat transfer efficiency in these systems is governed by conduction and convection forces, which are determined by the thermophysical properties of the fluids. An ethylene glycol/water mixture is the most common heat transfer fluid used, but it and propylene glycol suffer from less than optimal heat transfer efficiency. Glycols have low thermal conductivities and high viscosities, which degrade thermal performance, and they can have environmental and toxicity issues which limit their use in some applications.

A novel heat transfer fluid has been developed that offers both better heat transfer efficiency and a safer environmental profile than glycol systems. This fluid has individual thermophysical properties that are better than glycol systems, and may provide reduced fuel usage and higher throughput in line heaters. In addition, this new fluid is environmentally safe, being highly biodegradable if discharged, but having a low oxygen demand, reducing the chance of fish kill. The fluid is inhibited for prevention of corrosion, can be formulated for low freeze points, and is expected to be readily serviceable and stable for long life. This paper presents an analysis of the heat transfer process, a comparison of the novel fluid with glycols, and data from an initial pilot test of the system.
The Effect of Fluid Loss During Fracture Calibration Tests on the Main Treatment
Authors: Meyer Bruce R. , Jacot R. Henry
Published: December 2007

Fracture calibration tests (minifracs) are very successful methods for providing estimates of the fluid efficiency, closure pressure, fracture geometry and leakoff coefficient prior to the main treatment. The pressure decline data is normally analyzed using a Nolte type method for calibration and redesign of the main treatment.

Many times it has been observed that the main treatment has a higher efficiency (less fluid loss) than the minifrac which can adversely impact the fracture treatment. This paper addresses the effect of fluid loss during fracture calibration tests on the main treatment.

An analytical method for leakoff controlled by the filter cake and/or filtrate fluid has been developed for analyzing the effect of fluid loss in the formation prior to the main treatment. The main treatment leakoff velocity and volume loss equations account for the effects of the minifrac fluid loss behavior, including filter cake, spurt loss, mobility, time of fracture creation and relative fracture planes.

This paper presents the foundation for a generalized set of equations quantifying the effects of the minifrac fluid loss on the main treatment by conservation of mass and Darcy’s law. Equations are formulated for the main treatment leakoff velocity and volume loss. Numerous figures are provided that illustrate the parametric effects of the minifrac fluid loss on the main treatment efficiency and fraction of pad volume.
Hyperbolic Decline Parameter Identification Using Optimization Procedures
Authors: Jikich Sinisha A. , Popa Andrei S.
Published: December 2007

This paper describes two techniques for hyperbolic decline parameter identification. The first technique uses a genetic algorithm in the optimization procedure. The genetic algorithms are potentially useful in solving optimization problems when the objective function contains irregularities. The second technique uses linear regression for fitting a decline curve to data. The method weights equally the production rates during curve fitting, resulting in a stable solution. Consequently, the results are reproducible for a wide range of applications. Both methods were tested against field and literature data, demonstrating rapid, stable convergence and reproducible curves.
Reservoir Characterization Through Synthetic Logs
Authors: Mohaghegh S. D. , Goddard C. , Popa A. , Ameri S. , Bhuiyan M.
Published: December 2007

Magnetic resonance logs provide the capability of in-situ measurement of reservoir characteristics such as effective porosity, fluid saturation, and rock permeability. This study presents a new and novel methodology to generate synthetic magnetic resonance logs using readily available conventional wireline logs such as spontaneous potential, gamma ray, density, and induction logs. The study also examines and provides alternatives for situations in which all required conventional logs are unavailable for a particular well. Synthetic magnetic resonance logs for wells with an incomplete suite of conventional logs are generated and compared with actual magnetic resonance logs for the same well.

In order to demonstrate the feasibility of the concept being introduced here, the methodology is applied to a highly heterogeneous reservoir in East Texas. The process was verified by applying it to a well away from the wells used during the development process. This technique is capable of providing a better image of the reservoir properties (effective porosity, fluid saturation, and permeability) and more realistic reserve estimation at a much lower cost.
Scale Prediction in Geothermal Operations-State of the Art
Authors: Vetter O.J.
Published: December 2007

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

The production of brine from geothermal reservoirs is hampered by serious and very unique scale problems.

Presently, no reliable scale prediction models are available despite many efforts in this direction. None of the known models can be proven by field results except in some very proven by field results except in some very simple situations. This paper describes the state-of-the-art to stimulate desperately needed research on the subject.

A reliable scale prediction model must take into account:ThermodynamicsKineticsFluid-Dynamics

of every conceivable mechanism leading to scale depositions. Most mechanisms are not thoroughly known. In addition, many parameters or variables required for such a model are presently unknown. Many of the variables cannot be measured at all or within the required accuracy. The fluid-dynamics are especially obscure, but also many thermodynamic variables (brine composition, ph, enthalpies, partial mole properties, etc.) cannot be determined with present instrumentation under field conditions. Expected long-term problems within the reservoir, wellbore and problems within the reservoir, wellbore and surface equipment should be considered. The gigantic mass flow, unique for geothermal operations, is not well understood in many details and can create new and complex situations.

Present models are not scale predicting models but chemical models which could eventually become an integral part of reliable scale predicting models. Even these chemical models still predicting models. Even these chemical models still show vital shortcomings.

Introduction

SCALE IN GEOTHERMAL OPERATIONS

The production, utilization and/or reinjection of brine found in liquid-dominated reservoirs is often hampered by serious and very unique scale problems. Some of these scale problems are so severe that entire field operations are endangered. Some scale problems seem to be rather "harmless" at the present time, but could offer severe and costly long-term interferences with the economical and trouble-free production and utilization of these brines.
High-Performance Reservoir Simulation With Parallel ATHOS
Authors: Magras J-F. , Quandalle P. , Bia P.
Published: December 2007

One way to reduce uncertainties in reservoir simulation is to use geostatistical fine grids with little or no upscaling, but this approach can lead to excessively large simulations with literally millions of gridblocks. In the case of compositional studies, another way is to increase the number of components. Running this kind of large simulations requires the use of powerful computers with vector or parallel architectures.

In general, existing simulators must be restructured to make the use of parallel computers possible and efficient. Reengineering and re-writing of the source code are time and cost consuming for multi-purpose simulators. Previous papers have described the use of MPI (Message Passing Interface) to trigger parallel processing. This approach is delicate to manage as it involves incremental reengineering of the code, which is rather difficult to perform.

We present our experience of parallelization of an existing all-purpose reservoir simulator for shared memory platforms, using OpenMP instructions. The paper describes the methodology of parallelization in three incremental steps: first identifying the most CPU time consuming routines. Second, parallelizing these routines. Finally, developing efficient dedicated parallel preconditioned solvers. It is shown that this approach is easier to manage than the MPI approach while being as efficient on shared memory parallel architectures like SGI Origin2000, IBM SP3, or Compaq ES40.

Several large simulations, typically one million gridblocks, are presented to show the capabilities of ATHOS simulator on these parallel architectures. Simulations carried out on NEC SX5 are also presented, for comparison with a vector computer. These simulations include the main physical features of the ATHOS simulator used for black-oil, compositional and fractured reservoir studies.
Streamline Tracing on Curvilinear Structured and Unstructured Grids
Authors: Prévost Mathieu , Edwards Michael G. , Blunt Martin J.
Published: December 2007

The streamline method has proved to be extremely successful for reservoir simulation1. For a Cartesian grid the standard five point (7 in 3-D) discrete pressure equation is employed within the IMPES streamline method. The accuracy of the velocity field plays a critical role in the success of the technique, which relies on precise determination of streamline paths.

Modeling complex geology and geometry requires the use of sophisticated grids and thus the ultimate power of the streamline method will only be realized when the method is extended to general curvilinear grids.

In this paper a generalization of the Cartesian tracing algorithm is developed for general tensor fields on structured (corner point) grids and unstructured grids. The extension of the method requires the identification of appropriate volumes and fluxes over which tracing equivalent to the Pollock Cartesian method2 can be performed. Essential components of the method include the use of flux-continuous finite-volume schemes for the different grid types coupled with a novel flux recovery technique and a generalization of streamline tracing to polygons.
A New Streamline Method for Evaluating Uncertainty in Small-Scale, Two-Phase Flow Properties
Authors: Hastings J. J. , Muggeridge A. H. , Blunt M. J.
Published: December 2007

Variations of permeability and relative permeability due to small-scale heterogeneities, such as cross-bedding, can have a significant impact on reservoir performance1,2. These properties (particularly relative permeability) are typically very poorly quantified, and yet they represent an important uncertainty in predictions of oil recovery. However, it is currently impossible to model even a single realisation of these small-scale features with a field-scale finite difference simulator.

This paper presents a new, semi-analytical streamline method that allows rapid quantification of this uncertainty. The properties along each streamline are upscaled analytically to provide effective permeability, porosity, relative permeability and geometry for that streamline. This is achieved by a new method for upscaling total mobility in 1dimension, which, combined with an existing method for fractional flow3, enables us to reproduce production and watercut behaviour versus time for specified rate or pressure well conditions. Production curves from the streamlines are combined numerically to give field-wide values.

A stochastic model of a cross-section through a fluvial reservoir is used to demonstrate that the new method requires only a single pressure solution to calculate the distribution of oil recovery caused by small-scale variations in absolute and relative permeability.
Rapid History Matching Using a Generalized Travel Time Inversion Method
Authors: Wu Zhan , Datta-Gupta Akhil
Published: December 2007

We propose a generalized travel time inversion method for production data integration into reservoir models using finite-difference reservoir simulators. Our approach is motivated by seismic waveform imaging and is particularly well-suited for large-scale field applications because the computation cost depends only on the number of wells regardless of the number of parameters or the amount of observed data. Instead of matching the production data directly, we minimize a 'travel time shift‘ at each well derived by maximizing the cross-correlation between the observed and calculated production response. An optimal control method is used to compute the sensitivity of the travel time with respect to reservoir parameters. Finally, data integration is carried out via a modified Gauss-Newton method.

There are several advantages associated with the proposed travel time inversion method. First, it is robust and computationally efficient. The travel time misfit function is quasilinear with respect to changes in reservoir properties. As a result, the minimization is relatively insensitive to the choice of the prior model. Second, the computational cost associated with the sensitivity computation depends only on the number of wells which can be orders of magnitude lower than the number of parameters or the amount of observed data. This offers tremendous advantage over the commonly used gradient simulator method or the conventional adjoint methods that attempt to minimize the production data directly. Furthermore, the travel time approach also offers computational advantage during minimization of the misfit function using the Gauss-Newton algorithm. We have presented several examples to demonstrate the power, generality and practical feasibility of our proposed approach for large-scale field applications.
Combining Global and Local Optimization Techniques for Automatic History Matching Production and Seismic Data
Authors: Mantica S. , Cominelli A. , Mantica G.
Published: December 2007

Gradient based optimization techniques in computer-aided history matching are increasingly adopted by oil industries, because of the great time saving they can offer over conventional trial and error approaches. However, these methods lead to the identification of a single set of parameters, thus neglecting the inherent non-uniqueness of the solution of the underlying inverse problem. In this paper we propose a new approach that couple a chaotic sampling of parameter space with a local minimization technique. The first step is effected evolving a non-linear dynamical system, by which we identify several points to be successively used as initial guesses for a local, gradient based, optimizer. This provides a series of alternative matched models, with different production forecasts, that improve the understanding of the possible reservoir behaviors. The validity of this approach has been proven on a synthetic reservoir derived from a real West Africa field.
MPFA for Faults and Local Refinements in 3D Quadrilateral Grids With Application to Field Simulations
Authors: Aavatsmark I. , Reiso E. , Reme H. , Teigland R.
Published: December 2007

This paper extends the multipoint flux-approximation (MPFA) control-volume method to 3D quadrilateral grids for which the adjacent cells do not necessarily share corners. Examples are grids with faults and locally refined grids. This paper gives a derivation of the method for such grids.

The difference between two-point flux-approximation (TPFA) results and MPFA results for faults is demonstrated for synthetic problems. Further, the results are compared with results from uniform fine-grid simulations. The effect of repeated fault patterns as well as anisotropy is investigated. Large errors may be found for the TPFA method for flow through a series of faults in an anisotropic medium. Finally, a comparison is done for a reservoir field application.
Split Full Tensor Discretization Operators for Structured and Unstructured Grids in Three Dimensions
Authors: Edwards Michael G.
Published: December 2007

A full tensor velocity field occurs in reservoir simulation whenever the computational grid is non-aligned with the tensor principal axes. Three contributing factors that can give rise to a full tensor pressure equation in reservoir simulation are anisotropic media, upscaling (with cross-flow effects) and non K-orthogonal structured and unstructured grids.

The introduction of a full tensor typically increases the support of the standard scheme on a logically rectangular grid from 7 to 27 nodes in 3-D, which can increase simulation costs by over 100% in 3-D.

A major assumption in many simulators is that the pressure equation always has a diagonal tensor. The design and efficiency of such codes is intrinsically linked to the diagonal tensor assumption. However, when employing general non K-orthogonal grids with corner point geometry the diagonal tensor assumption leads to an O(1) error in velocity field.

The focus of this paper is on the development of finite volume schemes that maintain consistent full tensor flux approximations while retaining standard diagonal tensor Jacobian matrix inversion in three dimensions on structured and unstructured grids. Three dimensional Hexahedral and Tetrahedral grid examples are included which demonstrate the benefits of the method.
New Numerical Schemes for the Near-Well Modelling with Discretization Around the Wellbore Boundary Using Flexible Grids
Authors: Ding Y. , Jeannin L.
Published: December 2007

The control-volume schemes are discussed for the modelling of vertical wells using flexible grid.

The main difficulties of the well modelling in the reservoir simulation is the problem of the scale between the reservoir size (several kilometers) and the wellbore radius (several centimeters). In applications, although the wellbore boundary can be discretized using the flexible grid, the gridblocks in the well vicinity are usually not small enough compared to the wellbore radius, and the gridblock sizes vary usually geometrically in the radial direction from the well. This kind of grid makes the standard linear approach inefficient for the near-well flow modelling.

In this paper, new numerical schemes, which are based on logarithmic approach, are proposed to improve the standard linear approach for the near-well modelling. In particular, a multi-point and a two-point flux approximation scheme are presented. These schemes can reduce the calculation errors for the dominating "singular" well flow. Consequently, good results are obtained with these new schemes. The proposed approach can be used for any kind of flexible grid for the near-well modelling.
A Methodology for Simulation of Vuggy and Fractured Reservoirs
Authors: Kossack C. A. , Gurpinar O.
Published: December 2007

The proper treatment of oil recovery from vugs is an important part of evaluating a triple porosity reservoir. This paper evaluates the rate of oil recovery from isolated vugs, that is vugs that are not connected to the fracture system. Simulations of triple porosity systems are made with fine grid, single porosity and dual porosity and dual porosity models.

The effect of the ratio of viscous forces to gravity forces on oil recovery from vugs is evaluated for a wide rate of ratio of the forces.

A procedure is presented for creating composite curves (Pcow and krow) to be used in a dual porosity simulator to emulate oil recovery from triple porosity systems. This technique is designed for situations where no experimental displacement results are available. Discussions show that these composite curves are more reliable that the results from matching experimental displacements.

Two examples of this process are shown: one at a low and another at a high value of the viscous to gravity ratio. Two realizations are matched to demonstrate how one would create average composite curves in a field situation.
On Near Wellbore Modeling and Real Time Reservoir Management
Authors: Bøe Ø , Flynn J. , Reiso E.
Published: December 2007

This paper is concerned with the problems of real time reservoir management, simulation while drilling and near well bore modeling. These problems are discussed in terms of work process, feasibility as well as numerical and simulation related aspects. A software tool developed to perform high precision local simulation and at the same time account for global field behaviour is described. Field examples are presented to illustrate the potential and use for simulation while drilling exercises.
Numerical Subgrid Upscaling for Waterflood Simulations
Authors: Arbogast Todd , Bryant Steven L.
Published: December 2007

We present a subgrid-scale numerical technique for upscaling waterflood simulations. We scale up the usual parameters porosity and relative and absolute permeabilities, and also the location of wells and capillary pressure curves. Some of these are critical nonlinear terms that need to be resolved on the fine scale, or serious errors will result. Upscaling is achieved by explicitly decomposing the differential system into a coarse-grid-scale operator coupled to a subgrid-scale operator. The subgrid-scale operator is approximated as an operator localized in space to a coarse-grid element. An influence function (numerical Greens function) technique allows us to solve these subgrid-scale problems independently of the coarse-grid approximation. The coarse-grid problem is modified to take into account the subgrid-scale solution and solved as a large linear system of equations. Finally, the coarse scale solution is corrected on the subgrid-scale, providing a fine-grid scale representation of the solution. In this approach, no explicit macroscopic coefficients nor pseudo-functions result. The method is easily seen to be optimally convergent in the case of a single linear parabolic equation. The method is several times faster than solving the fine-scale problem directly, generally more robust, and yet achieves good results as it requires no ad hoc assumptions at the coarse scale and retains all the physics of the original multiphase flow equations.
Full-Physics, Streamline-Based Method for History Matching Performance Data of a North Sea Field
Authors: Agarwal Bijan , Blunt Martin J.
Published: December 2007

Streamline-based methods for history matching are appealing for two reasons. First, the forward simulation is potentially much faster than conventional simulation methods for displacement-type problems. Second, time-of-flight information along the streamlines can be used to find sensitivity coefficients in an efficient and elegant manner. However, current streamline history matching methods use forward simulations that ignore the effects of gravity and compressible flow. These effects may be critical in analyzing early-time performance data. If relevant physical effects are neglected in the forward simulation, the history matched reservoir description may not be consistent with the actual field, and predictions from the model will not be reliable.

We present a method for history matching watercut data using a streamline simulation that captures all the pertinent physics, including compressible three-phase flow with gravity. We use a methodology based on the assumption of one-dimensional flow along streamlines to find the sensitivity of water flow rate at production wells to changes in permeability. Although the computation of the sensitivities is approximate, the method provides a good history match for problems with significant effects due to compressibility and gravity.

Data from a North Sea field is used to test the technique. Using a full-physics streamline model gives a reasonable history match and a good prediction of future performance.
Scale Splitting Approach to Reservoir Characterization
Authors: Grimstad A. A. , Mannseth T. , Nævdal G. , Urkedal H.
Published: December 2007

Production forecasts are essential for sound reservoir management. The foundation for such forecasts is a characterization of relevant reservoir properties. These properties are usually determined through history matching, using production data, static well data (hard data), and the up-scaled geological model (prior model), simultaneously. This process if often very complex and costly, both in terms of CPU-time and man-hours.

To reduce cost and complexity of reservoir characterization, we propose an alternative methodology; scale splitting. This approach utilizes the fact that production data often contain information about variability of reservoir properties on a much coarser length scale than the other data do. Hence, production data alone can be used to determine the large-scale variation in the estimated properties. The selection of parameters that can be estimated from the production data are determined through a data driven, top-down search, starting with a single parameter representing the average property for the reservoir structure in question. One of the primary objectives of this search is to keep the number of parameters as low as possible, without sacrificing the match quality.

The prior model and the hard data need to be integrated to allow also for finer-scale property variation, and to match hard data at well locations. With scale splitting this is done at low cost after the history match of production data.

We present the scale splitting approach for absolute permeability estimation and give examples where it is compared to other approaches in terms of match quality and work load.
Uncertainty Analysis in Reservoir Production Forecasts During Appraisal and Pilot Production Phases
Authors: Steagall D. E. , Schiozer D. J.
Published: December 2007

The objective of this paper is to present a methodology for quantification of the impact of uncertainties in the economic evaluation of reservoirs. The methodology is based on the numerical flow simulation of many representative models of possible scenarios of the reservoir, through the combination of the attributes with uncertainty that characterize the reservoir. A set of data representing uncertainty values for each select attribute, and its associated probabilities are combined by the decision tree technique. After the simulation, a statistic treatment is done to obtain the expectation curve of production forecast and net present value. The procedure is done in a network of workstations, using parallel computing, with great reduction in the processing time and ensures the practical usage of this methodology. The methodology is applied to a real offshore field in Campos Basin – Brazil, in the appraisal phase, with few wells and few seismic lines.
An Integrated Partially Implicit Compositional Simulator for Naturally Fractured Reservoirs
Authors: Jigen Ye , Pingping Shen , Mingxin Liu , Chunqiu Guo
Published: December 2007

This paper describes an efficient method for solving the equations corresponding to an equation-of-state compositional model. The method is developed for a partially implicit compositional simulator in which the thermodynamic equilibrium equations and flow difference equations are solved separately and sequentially. The reduced system of linear equations consists of three equations with three unknowns per grid. So the equation number to be solved simultaneously is much less than that of the fully implicit method. Only pressure, oil saturation and gas saturation are solved implicitly in this partially implicit method while the total mole fraction of components is computed explicitly. If the increment of pressure as well as water saturation, gas saturation or total mole fraction of components of some grids is greater than a small given value, a implicit method can be applied easily to one individual grid to modify the calculation results.

An efficient integrated compositional simulator is obtained by combination of the simulator mentioned above with reservoir description model. The simulator can generate grid description input data and reservoir property input data conveniently according to the results of geological analysis, core analysis, well testing and log information. It can also help us view the simulation results and modify the geological model easily if necessary.

The partially implicit compositional simulator has been tested with several practical gas condensate reservoirs. Its simulation results are reasonably similar to those computed by fully implicit approach.
Chemical Treatment of Cuttings Drilled With Oil-Based Mud Employing a Laboratory Simulated Soil Washing Procedure
Authors: Perry M. L. , Griffin J. M.
Published: December 2007

With the emphasis being placed on environmental safety in recent years, companies are seeking economical methods for cleaning oil field waste. Drilling operations produce substantial amounts of such waste in the form of cuttings and used drilling mud. Oil-based or synthetic based muds, which are necessary in some drilling situations, increase the difficulty of cleanup operations due the increased hazards these fluids pose to the environment. One chemical washing agent has been identified that demonstrates potential for successfully reducing the TPH content of oil-based mud cuttings to below the required level.
Communication As A Tool Of Management
Authors: Oncken William
Published: December 2007

Introduction

Communication as a tool of management (administration communication) is that interchange of fact, viewpoints, and ideas which brings about unity of interest clarity of purpose, and integration of effort in a group of individuals organized to achieve a specific mission.

II. THE IMPORTANCE OF COMMUNICATION TO ORGANIZED EFFORT

A. Communication is an integral part of the management process to obtain production and efficiency.

Planning

Organization

Directing

Coordinating

Controlling

Communication is an integral part of the motivating process. People work to satisfy the following needs:

The need for opportunity

The need for recognition

The need for belonging

The need for security

Blocks to effective communication

The individual uses the language of personal motivation.

Management uses the language of production and efficiency.
A Mechanistic Model to Predict Natural Gas Separation Efficiency in Inclined Pumping Wells
Authors: Harun A. F. , Prado M. G. , Serrano J. C. , Doty D. R.
Published: December 2007

A new mechanistic model to predict the natural separation efficiency in deviated pumped wells has been developed based upon the combined phase momentum equations and a general slip closure relationship. The model incorporates two important parameters that are both functions of flow pattern; the local void fraction in front of the pump intake ports and the drag coefficient. The void fraction is, in turn, a function of the bubble rise velocity. The model uses existing void fraction and bubble rise velocity correlations developed by Hasan and Kabir1 for both bubbly and slug flow. The transition between bubbly and slug flow is determined by using the Hasan2 and Hasan and Kabir3 criteria. The Barnea et al.4 critical angle criterion below which bubbly flow cannot exist is also used by the model. A general drag coefficient correlation for slug flow has been developed based on data gathered by Serrano5 on a water-air system for inclination angles of 30 and 60 degrees.

Comparisons between the model's predictions and the experimental data of Serrano5 show excellent agreement. Sensitivity studies developed using the model indicates that the natural separation efficiency decreases as the liquid rate, inclination angle and gas-liquid ratio increase and as the annulus area decreases. For the wellbore configuration and operating conditions under investigation, the model predicts the existence of a minimum liquid rate below which the system reaches 100 percent gas separation efficiency.
Tip Screenout Designs and Alternative Height Growth Containment Techniques
Authors: Engels John N. , England Kevin W.
Published: December 2007

In March of 1999 a series of six hydraulic fracturing treatments were performed in an area of Algeria known as TFT (see Figure 1 ). Seven wells (6 producers and 1 injector) were to be fracture stimulated with risk of propagating into lower mobile water zone. A series of treatment design steps were carried out for each well that helped prevent excessive height growth while fracturing and ultimately limited water production after the treatments. The methodology incorporated utilizes both two-dimentional and pseudo three-dimentional fracture modeling in order to estimate different scenarios of fracture height growth. This method resulted in a better estimation of fluid volumes and pump rates that would limit height growth, yet optimize proppant placement and fracture conductivity in the productive part of the interval. The resulting net increase in oil production from the six producer wells was over 29.93 m3/hr. This paper explains the design methodology used during the campaign and presents representative case histories.
Inflow Performance Relationship for Perforated Horizontal Wells
Authors: Yildiz Turhan
Published: December 2007

This paper presents a comprehensive investigation of perforated horizontal well performance in areally anisotropic reservoirs. Theoretical investigation is based on a general 3D analytical IPR model. The analytical IPR model considers an arbitrary orientation and distribution of perforations along the completed segments. Changes in flow rate, pseudo-steady state productivity, and cumulative production can be computed using the solution.

The analytical IPR model was compared with the models available in the literature and verified. It was then used to investigate the effects of well and reservoir parameters on the inflow performance of partially perforated horizontal wells.
Prediction of Specific Productivity Index for Long Horizontal Wells
Authors: Cho Hyun , Shah Subhash N.
Published: December 2007

As the length of a horizontal well is increased, its drainage area also increases. Productivity of a long horizontal well is no longer proportional to the well length because increase in the length of horizontal production section also causes frictional losses in the wellbore. However, no reliable standards are currently available that take into account quantitatively the parameters necessary for the calculation of productivity index in long horizontal well.

A new approach of the specific productivity index is proposed to predict the production rate considering friction losses in long production section under inflow conditions. This paper specifically describes model development, solution and the simulation results for the production of a long horizontal well with the specific productivity index. This specific productivity index is derived by assuming steady-state flow of a slightly compressible fluid in an anisotropic formation. The influence of wellbore damage near the horizontal wellbore is also considered in the model. The sensitivity study of the various parameters affecting productivity is performed and the results are analyzed quantitatively. The study shows that there is a critical point, where rate of friction pressure is suddenly increased and productivity index is decreased abruptly with increase in horizontal well length beyond this point. This critical point is the tangent point on which friction losses should be considered for production estimation. The model facilitates determination of the new horizontal productivity index considering friction losses in long horizontal wells.
Liquid Petroleum Confinement System
Authors: Pierson R. M. , Lucken J. E. , Shaver H. W.
Published: December 2007

The Liquid Petroleum Confinement System, (L.P.C.S.), has been designed and constructed to prevent the loss of produced crude oil into the Earth's atmosphere by retention and storage in a confined system. Historically, the petroleum industry has stored produced crude oil at individual surface well locations incorporating one or more standard atmospheric stock tanks. Crude oil stored in this manner undergoes certain physical changes, due to the vapor pressures of the escaping major constituents of the crude oil being greater than atmospheric pressure, causing "differential" and "flash vaporization". The crude oil in this physical state is observed in the form of gas and can be described by applying Boyles Law and Charles Law into the "Ideal Gas" equation PV = nRT. Any change in volume, temperature or pressure with respect to the crude oil, at the constantly changing physical and atmospheric conditions under which it is stored, causes a loss of the crude oil to the atmosphere. This loss can be as high as 50% or more of the daily produced crude oil volume resulting in atmospheric pollution and contamination as well as lost revenues to both the working interest and royalty owners. The L.P.C.S. provides an environment of storage in which the rate of vaporization and condensation become a steady state of "dynamic equilibrium". Thus the molecules of crude oil entering the vapor phase in random motion strike the surface of the liquid and are recaptured. The excess molecules can also be returned to collection and used as an on site fuel gas. The L.P.C.S. offers working interest and royalty owners' protection from the loss of production while increasing crude sales. The L.P.C.S. helps to prevent atmospheric pollution and contamination and becomes a highly efficient investment alternative to conventional atmospheric stock tanks and expensive vapor recovery systems.
Use of Concrete Technology for High-Density Cement Systems in South Texas
Authors: Pokhriyal Jai , Gaudlip Tony , Suter William R.
Published: December 2007

Historically cementing the deep high-pressure, high temperature (HPHT) gas wells in South Texas has often exceeded the capabilities of existing technology. The high-density mud systems and narrow margin between pore and fracture gradients require efficient mud removal and stable slurries with low equivalent circulating densities, and effective gas migration control, especially when cementing ‘slim hole’ completions. The high bottom hole temperatures along with the use of long liners where the static temperature at the top of liner (TOL) is often less than the bottom hole circulating temperature (BHCT) place additional requirements on the slurry designs to ensure early compressive strength development at the TOL.

A liquid concrete slurry system based on optimizing the packing volume fraction (PVF) of the dry blend using sized inert particles provides a cost-effective solution to cementing these HPHT wells. Using the concept of liquid concrete technology, slurry properties are a function of the dry blend rather than additives. Adjusting the particle size distribution enables the density, compressive strength and rheological properties of the slurry to be tailored for specific well conditions. The use of inert particles reduces the concentration of cement additives by approximately 50% making it possible to have extended pump times while ensuring rapid compressive strength development at the TOL when using an inorganic ‘set control’ additive.

By optimizing the PVF of the dry blend the permeability and porosity of the set cement are reduced due to improved particle packing. This makes it possible to provide a cost-effective solution to annular gas migration control.

High-density concrete slurries from 16.5 PPG to 23.0 PPG have been utilized to successfully cement HPHT gas wells with bottom hole circulating temperatures in excess of 400 °F. These slurries exhibit low rheologies, fast early compressive strength development and effective gas migration control.

This paper outlines the development and application of high-density liquid concrete slurries and their utilization in cementing HPHT gas wells in South Texas.
Laboratory Instrumented Sucker-Rod Pump
Authors: Podio A. L. , Gomez Jaime , Mansure A. J.
Published: December 2007

Although sucker rod pumps are installed in nearly 90% of all oil wells in the United States and have been widely used for decades, there are many issues regarding their performance that are not well understood. This is due to the difficulty of obtaining downhole pump-performance data. Many persistent problems in sucker rod pumping including partial pump fillage, gas interference, gas locking, fluid pound, sticking valves, rod downstroke compression loading, equipment failure, reduced production, etc. are difficult to diagnose from the surface. Currently, verification of sucker-rod pump problems can only be inferred by removal of the pump at great expense. Thus, root cause analysis depends on guesswork and component analysis. Knowledge of pump characteristics downhole would allow problems to be predicted rather than simply diagnosed after they have persisted long enough to result in failure

To develop a knowledge base of sucker-rod pumps, a two-fold approach is being pursued: first, instrumentation of a clear sucker-rod pump in the laboratory followed by the development of an instrumented downhole pump. The laboratory pump allows the development of diagnostic techniques where the pump performance can be verified visually. The downhole pump will allow testing at field conditions.

A key element to both the laboratory and downhole instrumented pumps is measuring the compression chamber pressure -- pressure within the pump barrel. The instrumentation has been designed to collect high-speed (≥100 samples a second) data so that transient behavior (ball chatter, etc.) can be observed. Data is being archived operating the pump under a various conditions from full to pumped-off.

This paper presents results of tests with the laboratory pump that have resulted in new insights about pump friction and the development of techniques to measure dynamic and static pump friction. Analyses of the compression-chamber pressure are leading to a better understanding of what happens during that time when both valves are closed and to the development of techniques to perform real-time diagnosis determining fillage and gas locking. Laboratory data has shown that compression chamber data can be more insightful in understanding pump conditions.