bluuebunny/crossref_metadata_2025_split huggingface dataset:
A System for Estimating Uncertainties in Hydrocarbon Pore Volume
Authors: Siring Erling 
Published: December 2007

ABSTRACT
This paper describes a Monte Carlo simulation system based on SAS (Statistical Analysis System), called MCS. The system has been designed to handle dependencies between variables and to integrate results from geostatistical programs with ordinary Monte Carlo simulations.
MCS has been developed in Statoil to estimate the uncertainties in Hydrocarbon Pore Volume in gas and oil fields. Special care has been taken to handle dependencies between petrophysical variables and rock volumes in different reservoir zones and fault block segments.
A Log-Inject-Log Application to Resolve Porosity in Tight, Fractured Formations
Authors: Bigelow E. L. 
Published: December 2007

ABSTRACT
Petrophysical evaluations offractured reservoirs are always adifficult task. Recognizing fractures, determining their orientation, and identifying whether they are healed, partially healed, or open is itself difficult. In fractured reservoirs, conventionallog analysis methods rarely provide accurate porosity and saturation solutions with respect to productivity or reserve calculations. This article proposes a pulsed neutron log-inject-log technique as a method to provide more accurat porosity calculations in reservoirs that have extremely low matrix porosity, but produce from fracture systems.
Proposal for an Integrated Study of the Grayburg/San Andres Reservoir, Foster and South Cowden Fields, Ector County, Texas
Authors: Rowland D. A. , Reeves J. J. , Trentham R. C. , Smith W. H. 
Published: December 2007

Abstract
A cooperative study of the Grayburg/San Andres reservoir is planned for the Foster and South Cowden Fields, Ector County, Texas under the U.S. Department of Energy's Class II Program for ShallowShelf Carbonate. The project will utilize existing technology to increase oil production through infi11dri11ing, workovers, and water flood development. Productivity problems associated with a mature shall owshelf carbonate reservoir will be addressed by a multidisciplinary tech­ ni cal team which integrates high resolution 3-D seismic data, reservoir characterization techniques, and 3-D reservoir simulation.
A 3-D seismic survey designed specifically for i magi ng the Grayburg/ San Andres interval of the Foster and South Cowden fields will be acquired. A high performance computer work­ station will then be used to integrate existi ng subsurface geological and engineering data with the 3-D seismic data for a detailed evaluation of sequence strati graphy and facies relationships. Subsequentl y, a 3- D reservoir simulation model will use the results to hel pdefine flow units wi thin the reservoir. A field demonstrati on of in fill dri11ing and water flood deve1 opment wi11 follow.
The high resolution 3-D sei smic survey is expected to resol ve changes in the subsurface on the megascopic scal e, al l owi ng for carre­ lation of pet rophysical properties and stratigraphic information between boreholes. This informati on will be helpful in mapping porosity zones, permeability barriers, and "thief" zones within the reservoir.
DOE Class II Oil Program: Application of Reservoir Characterization and Advanced Technology Improves Recovery and Economics in Lower Quality San Andres
Authors: Taylor A. R. , Doty R. L. , Behm E. J. , Ulmschneider Rene , Watts George , Hickman T. S. , Underwood George , Justice J. H. 
Published: December 2007

Abstract
This proposal is aimed at proving lower quality San Andres Reservoirs can be economically flooded by applying reservoir characterization and a combination of EOR methods that are not widely utilized. This site is representative of DOE Class II reservoirs and is uniquely suited for the successful application of advanced technology. The reservoir characterization methods will apply new technologies which include cross wellbore tomography, hydraulic fracture orientation detection, and 3D seismic. The intent of this proposal is to show that, using commercial resources available to all producers, oil remaining after waterflooding can be economically recovered using C02 flooding and Cyclic C02 stimulation in reservoirs more heterogeneous and of lower quality than current C02 projects.
Work proposed will begin with reservoir characterization using conventional geological and petrophysical methods incorporating 3D seismic and cross wellbore tomography. This characterization will be used in a compositional simulation study to provide production schedules for economic evaluation. The improved simulation model will be able to provide production forecasts for conventional miscible C02 flooding and provide the added benefits of forecasting recoveries from the Cyclic C02 stimulation and increased injection from fractured injection wells. The Cyclic C02 stimulation process provides an almost immediate production increase, and thus the quicker payouts needed to economically justify the large capital outlay required to bring C02 to the field. The ability to accurately provide forecast production during this early phase is essential to performing a realistic economic evaluation of the project. Another factor influencing C02 floods is unfavorable mobility ratios which cause poor sweep efficiency, thus processing only a small portion of the reservoir. Improving the sweep efficiency would increase recoveries by an estimated 1015% in the flood area.
Improved Reservoir Management with Water Quality Enhancement at the North Robertson Unit
Authors: Nevans J. W. , Pande P. K. , Clark M. B. 
Published: December 2007

Abstract
The quality of injection waters used in any new or existing waterflood or EOR ·process should be considered as a critical component of reservoir management and surveillance programs. Despite decades of industry experience with recovery processes utilizing water in the Permian Basin (and most other major oil producing basins of the world), water quality is an often neglected aspect of reservoir management programs. Consequently, severe injectivity and operational problems are frequently experienced.
This paper describes a case study of water quality control for the Clearfork and Glorieta reservoirs (Permian age) of the North Robertson Unit (NRU) located in the Permian Basin of West Texas. A cost-effective surveillance program for the timely identification and treatment of potential water quality control problems has been designed and implemented. Integration of geological and reservoir parameters, which are crucial to ensure the realization of optimal reservoir performance and operational objectives, is highlighted.
Transient Well Testing of Coalbed Methane Reservoirs with Horizontal Wells
Authors: Sarkar P. S. , Rajtar J. M. 
Published: December 2007

ABSTRACT
Natural gas production from coalbeds using horizontal wells may be of interest to producers in the future. Since sedimentary gas reserves are limited, the unconventional gas reservoirs could be an alternative resource to meet the demand for natural gas. Naturally fractured coalbeds with their dual porosity character can produce at much higher rates with horizontal wells. The presented paper shows an analytical solution for transient pressure response of a horizontal well in a coalbed reservoir. Effects of wellbore storage and skin on the solution are illustrated. The solution is developed for a semi-infinite, anisotropic coalbed reservoir assuming single phase gas flow. The solution can be used to generate type curves for particular reservoir geometry and subsequent determination of reservoir parameters.
The paper illustrates the application of type curve matching for a typical case through an example on computer generated data.
Pregel Blender Prototype Designed To Reduce Cost and Environmental Problems
Authors: Allen T. E. 
Published: December 2007

Abstract
A new pregel blender is being developed to continuously mix dry gel on the fly for fracturing treatments. Specifically, this system can either continuously mix dry gel at the job concentra-tion the operator selects, or mix a liquid concentrate that is later diluted to the required final job concentration. A holding tank is provided to hydrate gels for both modes of operation.
The proposed system has several major economic and environ-mental advantages over previously designed preblenders. Not only should it provide a gel quality comparable to a liquid gel concentrate (LGC), but it will not require diesel and/or the other chemicals required to make LGCs. As a result, the system should save time and expense over LGC processes and conven-tional batch-mixing, while being safe to use in environmentally sensitive areas.
Hydraulic Fracturing of the Multizone Wells in the Pegasus (Devonian) Field, West Texas
Authors: Olson K. E. , El-Rabaa A. W. M. 
Published: December 2007

ABSTRACT
A large developmental program in the Pegasus (Devonian) field commenced in early 1990. The program triggered a completion optimization process aimed at effectively stimulating the Pegasus wells, as well as reducing cost. Elements of optimization included are the field and laboratory data gathering efforts, the integration of data into the stimulation design, and the field and laboratory diagnostics. The completion costs were reduced by more than 40%, which translated into 20% savings in the overall well cost.
The New, Generalized Material Balance as an Equation of a Straight Line: Part 2 – Applications to Saturated and Non-Volumetric Reservoirs
Authors: Walsh M. P. , Ansah Joseph , Raghavan Rajagopoal 
Published: December 2007

ABSTRACT
This paper is the second in a two-part series of papers which features practical applications of the generalized material-balance equation. Applications to initially-saturated and non-volumetric reservoirs are discussed in this paper (Part 2); applications to initially-undersaturated, volumetric reservoirs are discussed in Part 1. Graphical methods to estimate the original oil and gas in-place are presented. The graphical methods are general and are applicable to the full range of reservoir fluids of interest. Example calculations are carried out for gas-cap and water-influx reservoirs. These examples, along with those discussed in Part 1, demonstrate the extraordinary power of the generalized material-balance equation.*
Laboratory Study on Surfactant-Based Selective Mobility Control
Authors: Dixit Amulya , Tsau Jyun S. , Heller John P. 
Published: December 2007

ABSTRACT
Carbon dioxide flooding has been recognized as an efficient means of recovering oil. However, the efficiency is marred due to the unfavorable mobility ratio between CO2 and the oil to be displaced and die poor sweep efficiency resulting from the heterogeneity of the reservoir. The goals of this study are to develop a quick and efficient method to explore the possible application of foam in mobility control, and to identify available surfactant in such an application to increase the sweep efficiency, and therefore the oil recovery. Some of the results from this study show that mobility of CO2 is significantly reduced by using the foam. In addition to that, a possible characteristic of foam in selective mobility reduction (SMR) is also observed in some of the tests in which the CO2-foam mobility was found to be lower in higher permeability rock samples than that in lower permeability rock samples. In other words, the flow of foam is likely less mobile in a more permeable porous media than that in a less permeable region of the reservoir formation. This behavior is favorable to preserve the uniformity of a flood front as it propagates through the rocks with nonuniform permeability. Based on limited data, however, the SMR is found to be dependent on flow rate and on the type of rocks when using the same surfactant.
A New Pre-Production Well Test for Analysis of Multilayered Commingled Reservoirs With Unequal Initial Pressures
Authors: Aly Ahmed , Lee W. J. 
Published: December 2007

ABSTRACT
The main objective of this paper is to design a new well test that will unable us to determine the individual layer properties (layer permeability, layer porosity, layer diffusivity and layer skin) early in the life of the reservoir, taking into considerations cost, time and the environmental impact of well testing. The pre-production well test is a well test that is carried early in the life of the reservoirs when the information is most needed for planning production schedule and economic decisions concerning the life of the wells. Pre-production is the period after completion but before production of the well. Directly after perforations, we position a pressure gauge above the top perforation to measure the pressure performance from the total system (two or three layer systems). Cross flow in the wellbore from one layer to another will cause the pressure signal. The cross flow is due to the differential pressure between the layers. One important advantage of the pre-production well test is that there is no production on surface during the test. Thus, the environmental impact caused by flaring oil or gas during a conventional well test is all eviated.
In this paper we developed a general mathematical solution to model the reservoir performance of commingled reservoirs with unequal initial pressures in Laplace space. The reservoir performance information available from this model includes wellbore pressures, layer sandface flowrates and layer cumulative production.
The computational solutions developed are used to model the reservoir performance for two layered and three layered cases from the literature. The results are verified by comparing them to the results generated using a finite-difference simulator. The agreement was found to be excellent for all the tested cases.
We developed the "Derivative Extreme Method" (DEM) for the analysis of the wellbore pressure measured during the pre-production well test. The DEM determines layer properties from early and middle time region data. Thus, well testing time is reduced.
Compositional Simulation of Carbonated Waterfloods in Naturally Fractured Reservoirs
Authors: Shenawi S.H. , Wu C.H. 
Published: December 2007

SPE Members

Abstract
This paper presents a compositional simulation of imbibition carbonated waterfloods in naturally-fractured reservoirs using a 3-dimensional, 3-phase, dual-porosity, compositional simulator (COMABS). The simulator is developed as a part of multi-disciplinary study to improve the oil recovery from low-permeability, naturally-fractured reservoirs such as Austin chalk trend. Laboratory imbibition carbonated waterfloods data using chalk cores are available for this study. The COMABS allows the partitioning of CO2 from the injected water phase into the oil phase based upon the CO2 solubility in each phase. The partitioning of CO2 is assumed to reduce oil phase viscosity and increases oil density; the transmissibilities are updated as a function of CO2 concentration.
Two grid systems are used in a cross-sectional, dual-porosity modeling of the laboratory tests. For simplicity, three dual-porosity gridblocks are used to represent the laboratory laboratory flow test systems. The carbonated water imbibes into the matrix blocks and causes the counter-current flow of oil from the matrix to the fracture. Then, fifteen dual-porosity gridblocks are used. In this system, a higher fracture permeability value is assigned for the gridblocks corresponding to the fracture in the laboratory flow test system. The simulator is capable of matching the laboratory imbibition oil recoveries. The effect of the carbonation of injected water on oil recoveries are examined with computed oil saturation, oil viscosity, oil density and CO2 concentration distributions.
A hypothetical two-dimensional field imbibition carbonated waterflood is used to demonstrate the use of COMABS for field-scale applications. The application of the simulator for field-scale imbibition carbonated waterflood may provide some insights on the impacts of imbibition and compositional variation on imbibition CO2-enriched waterflood recovery.

Introduction
The average conventional waterflood oil recovery from low-permeability, naturally-fractured reservoirs is low because the injected water may preferentially channel through the highly interconnected fractures. In the process, a portion of the injected water will imbibe into the tight rock matrix due to capillary forces and expels the oil from the matrix into the fracture. Injected water then displaces the expelled oil through the network of fractures to the producing wells.
P. 31^
Use of Simulators in the Design of an Experiment for Steam Injection into a Fractured System
Authors: Sumnu M. D. , Aziz Khalid , Brigham W. E. , Castanier L. M. 
Published: December 2007

Abstract
To simulate steam injection in fractured reservoirs either double porosity or double permeability models are used. Both incorporate a matrix-fracture transfer term in the mass and energy balances. Due to the difficulty in modeling the physical processes taking place in the matrix-fracture transfer and the lack of experimental data, the matrix-fracture transfer term is not fully understood. This is especially true for nonisothermal processes.
Fine grid simulation results are used to design a 3-D laboratory matrix-fracture model to study the matrix-fracture transfer function for steam injection. A CT-Scanner will be used to measure the three-phase insitu saturations in the fractured model. The flow parameters were determined by using the results of several simulation runs. Among these are the steam injection rate, maximum expected pressure in the system and the number and the locations of the injection and production wells needed to clean and saturate the model for each run. Analytical heat transfer models were used to determine the heat losses from the model.
Fine grid simulations were used to investigate the sensitivities of the flow process to matrix-fracture properties such as capillary pressure and relative permeability. The simulations showed that matrix water-oil capillary pressure increased the oil recovery by increasing the water imbibition rate. On the other hand, fracture water-oil capillary pressure decreased the water imbibition rate and recovery. Matrix gas-oil capillary pressure had no effect on the oil recovery but fracture gas-oil capillary pressure had a positive effect on recovery by allowing flow of steam into the matrix thus increasing oil mobility. The effect of matrix relative permeability was found to be less important.
The experimental design was modified based on the numerical results. We give details of the experimental apparatus and show some results from preliminary experiments.
A Stream Tube Model for the PC
Authors: Dobitz U. K. , Prieditis John 
Published: December 2007

Abstract
CO2-Prophet, a water and gas flood prediction software product, has been developed by Texaco with support of the U.S. Department of Energy (DOE). This paper describes the model and presents case comparisons with physical models and commercial reservoir simulators.
CO2-Prophet has been shown to be a good tool for screening and reservoir management and is being released to the industry complete with a detailed user manual. Ease of use was emphasized in the development of the user interface. CO2-Prophet runs on PC compatible computers and following are some of its features:
A front end for easy reservoir parameter input. Several predefined patterns to simplify use. The ability to design patterns to fit most situations Fast computation. Multiple flood regimes so water, gas, and miscible floods can be modeled. Output in surface units and dimensionless formats. Output designed for importing into a spreadsheet
CO2-Prophet computes streamlines between injection and production wells to form stream tubes. It then makes flow computations along the stream tubes. The mixing parameter approach, proposed by Todd and Longstaffis used for simulation of the miscible process. CO2-Prophet uses the Dykstra-Parsons2 coefficient to distribute the initial injection into a maximum of ten layers, and then fractional flow calculations determine the flows and fluid saturations along the stream tubes. Program inputs are pattern description, relative permeability curves, initial saturations, injection rates, and reservoir-to-surface conversions. A new case can be set up and run in a few minutes making this program ideal for the screening of EOR projects and pattern comparisons.
The hardware requirements to run CO2-Prophet are an Intel® 386 based PC or better with at least 4 megabytes of RAM and 4 megabytes of disk space free. A math coprocessor is required for 386 or 486SX systems.
Project Design of a CO2 Miscible Flood in a Waterflooded Sandstone Reservoir
Authors: Davis D. W. 
Published: December 2007

Abstract
The Port Neches CO2 miscible flood project began CO2 injection in September, 1993 into a waterflooded sandstone reservoir along the Texas Gulf Coast. Sponsored by the U.S. Department of Energy (DOE) in their Class I Oil Program, this project will determine the recovery efficiency of CO2 flooding a sandstone reservoir which has been extensively waterflooded down to a residual oil saturation of 30%. The design of this project utilized the various tools available for predicting the recovery performance of such projects, with DOE's CO2 Predictive Model CO2PM1 and a compositional model being used. In addition a streamtube model2,3 has been developed to predict the recoveries associated with the waterflood and CO2 recovery processes. The validity of this streamtube model, the CO2PM program, and previous compositional reservoir simulation work, has been evaluated by the use of a compositional five-spot model where an equation-of-state for the current reservoir oil is incorporated. This work points out the streamtube model's ability as an effective screening device for CO2 flood prediction. Furthermore, the importance of properly characterizing the permeability within each layer of the reservoir is demonstrated by the improved recoveries seen in fining-upward sequence reservoirs.