bluuebunny/crossref_metadata_2025_split huggingface dataset:
Use of Transient Rate and Pressure Data To Determine Drainage Area Average Reservoir Pressure Without Shutting In the Well
Authors: Ahmed Usman , Hendrix J. L. , Schwanitz B. J. 
Published: December 2007

Abstract
Drainage area average reservoir pressure , p¯, is an important reservoir parameter needed to define reservoir potential and also to plan and evaluate performance of various flooding processes. In certain countries and states, Alaska for one, the state oil and gas department requires the measurement of p¯ annually on designated wells. Typically, p¯ is estimated by shutting in a well and performing either a conventional pressure build-up test or taking static pressure measurements at designated intervals. In both the scenarios, test times can be days to weeks depending on the formation permeability. In the case of static pressure test, error bounds can be significant.
In this paper we present an alternate technique that allow the estimation of p¯ without shutting in the well and performed in a relatively short period of time. The technique was developed in conjunction with BP Exploration in Alaska by modifying Schlumberger’s existing Transient Rate and Pressure (TRAP) testing analysis. The technique involves imposing a transient on the formation; and the rate convolved pressure is used in conjunction with the Mathews-Brons- Hazenbroek (MBH) method to calculatep¯.
The project described in the paper consist of developing the technique and applying to six wells. In several cases long term build-up data was available for comparison. The comparison was very good and following a review by the State of Alaska regulatory board the technique was approved as a replacement for long term shut-in tests.
Slim-Hole and Coiled-Tubing Window Cutting Systems
Authors: Faure Alban , van Elst Herman , Burge P. M. , Jürgens Rainer 
Published: December 2007

ABSTRACT
With re-entry drilling systems available for hole sizes as small as 3-7/8", slimhole re-entry horizontal drilling offers operators an opportunity to improve field recovery and revitalize wells suffering from gas or water coning by infill drilling. In particular, the potential for coiled tubing drilling has created significant industry interest over the last 18 months. Offshore where there is no derrick in place, use of a coiled tubing drilling system makes it possible to redrill old wells and perform horizontal re-entries.
To date, coiled tubing re-entry wells have used a conventional rig to cut the window, adding unnecessary costs and time to the program. It was recognized that a coiled tubing conveyed window cutting system will enhance the capabilities of coiled tubing drilling by eliminated the need to cut the window with a conventional rig.
The problems of slimhole window cutting include controlling weight on bit while starting the window, and reducing torque while milling to prevent drillpipe failure.
In the coiled tubing application, rotation is supplied by a downhole motor, which presents additional problems with respect to controlling weight on bit.
A milling system that combines downhole motors with hydraulic thrusters to supply constant weight on bit has been bench-tested and field proven. While the prototype system required three milling runs after setting and orienting the packer, subsequent systems are in testing to reduce the number of milling runs to one.
A description of the applications and requirements of the window cutting system is provided, along with bench test and field test results.
Potential of the Cyclic CO2 Process in a Waterflooded, Light Oil, Shallow Shelf Carbonate Reservoir
Authors: Wehner S. C. 
Published: December 2007

Abstract
The goal of this Central Vacuum Unit Project is to demonstrate the CO2 Huff-n-Puff process in a light oil, shallow shelf carbonate reservoir within the Permian Basin. The CO2 Huff-n-Puff process is a proven enhanced oil recovery (EOR) technology for Louisiana­ Texas gulf coast sandstone reservoirs. The reader is referred to three Society of Petroleum Engineers (SPE) papers, No. 15502, 16720 & 20208 for a review of the theory, mechanics and case histories of the process. The process has even been shown to be moderately effective in conjunction with steam on heavy California crude oils. Although the technology is proven in sandstones, it continues to be a very underutilized EOR option for carbonates.
Application of Integrated Reservoir Management and Reservoir Characterization to Optimize Infill Drilling
Authors: Pande P. K. , Clark M. B. , Blasingame T. A. , Kelkar Mohan , Vessell R. K. , Hunt P. E. 
Published: December 2007

Abstract
This project demonstrates the application of Advanced Secondary Recovery (ASR) technologies to remedy producibility problems at the North Robertson (Clearfork) Unit, in Gaines County, Texas. The North Robertson (Clearfork) Unit is a Shallow Shelf Carbonate (SSC) reservoir of Permian-Leonardian age operated by Fina Oil and Chemical Company. The Department of Energy (DOE) has selected the Unit as a Mid-Term Field Demonstration under the DOE Class II Oil Program.
Improved Analytical Solution for Real Gas Flow in Porous Media
Authors: Chien Tony , Caudle S. H. 
Published: December 2007

ABSTRACT
The real gas potential function presently being used in the oil and gas industry does not yield valid solutions when the reservoir pressure falls substantially below the initial value. To tackle this problem, a new real gas potential has been implemented. The effects of pressure-dependent fluid and rock properties such as gas viscosity, compressibility, porosity and permeability have been considered. Advanced mathematical derivations with respect to nonconstant hydraulic diffusivity have been performed, and an analytical solution has been obtained. Solutions for multiple-rate and multiple-well systems as well as bounded reservoirs of any shape have been successfully developed by using the principle of superposition and an unsteady-state bounding technique. Validation of the analytical solution has been favorably achieved by comparison with a finite-difference simulation. Reservoir pressures and flowing bottomhole pressures in gas wells calculated by the analytical solution presented in this paper are more accurate than by other analytical methods previously available in the literature.
Original Gas in Place and Decline Curves from Early Stabilized Rate-Time Data
Authors: Keating J. F. , Chen H. Y. , Wattenbarger R. A. 
Published: December 2007

ABSTRACT
With the method presented in this paper, early rate-time data can be extrapolated to estimate original gas in place (OGIP) and a future decline curve. The advantages of this new method are: (1) OGIP can be determined as early as possible without shutting in the well, (2) a future decline curve for a constant flowing bottom hole pressure can be calculated and (3) the only data needed are rate-time data, an estimate of the initial reservoir pressure, and an estimate of the constant flowing bottom hole pressure. The disadvantage of this method is that it assumes stabilized flow for the future decline curve. Verification of the method was obtained by comparing results with one field case and 16 simulator cases.
CO2 Operating Plan, South Welch Unit, Dawson County, Texas
Authors: Hill W. J. , Tinney T. J. , Young L. C. , Stark K. L. 
Published: December 2007

ABSTRACT
The South Welch Unit of the Welch Field commenced full scale injection of CO2 beginning in September of 1993. The flood design was based on the performance of a 180 acre pilot conducted from 1982 to 1987. A compositional model study of the pilot performance was used to design a CO2processing facility and the full scale flood operating approach. Primary, secondary and tertiary performance matching were used to verify the reservoir and process description and to forecast performance under a full field scenario. Scaleup was based on floodable pay from the modeled area related to the remaining areas under consideration for flood.
Reservoir simulation and economic analysis were used to investigate water alternating gas (WAG) cycle lengths, WAG ratio, and total slug sizes. Phasing of areas was coupled to level plant loading considerations, water handling limits, and short term profitability to develop an operating plan for the Unit.
A Proven Methodology for Comparison of Cement Acid Solubility
Authors: Carpenter R. B. , Edwards T. M. 
Published: December 2007

ABSTRACT
While there have been several good papers that describe the dissolution of Portland cement by hydrochloric:hydrofluoric acid (HC1:HF) solutions, no one has established a detailed comparative test procedure.1-3 The absence of a single, specific methodology left all parties to form their own interpretations of the acid solubility test described briefly in SPE 18986.
Discrepancies between the various procedures produced inconsistent results. Some laboratories were keeping the heated acid in glass vessels for extended periods before the cement specimen was introduced. Using glass vessels allows the HF to spend on the glass instead of the cement. Others were using grease on the curing molds and testing the cubes without adequate grease removal; this limits cement/acid contact. Different methods for agitating the acid and suspending the cement cubes in the acid were also being employed. One company was desiccating the specimens before acid immersion; another was using a complete inhibitor and surfactant package. Even the concentration and volume of acid was not universally agreed upon. All these factors must be controlled for an accurate comparison of data between different laboratories
Representatives from two operating companies have developed a jointly endorsed and very explicit methodology for conducting cement acid solubility tests. Equipment, chemicals, preparation methods and report forms were specified in extreme detail. This procedure was designed to address the above mentioned problems and yet be cost effective and applicable in any field lab.
Although the new test remains qualitative, it has provided consistent comparisons of conventional and microfine Portland cements. A quantitative method would require more costly, specialized equipment and limit field application.
This procedure provides a sound method for evaluating the relative acid solubility rates of various cement blends. It can also be used as a tool for developing improved cement designs or quality control procedures.
Integrated Recovery Efficiency Forecast Models for San Andres Reservoirs of Central Basin Platform and Northern Shelf, West Texas
Authors: Shao Hongbin , Brimhall R. M. , Ahr W. M. , Wu C. H. 
Published: December 2007

ABSTRACT
This paper presents integrated recovery efficiency forecast models of primary, initial waterflood and infill drilling for San Andres reservoirs in the Central Basin Platform and the Northern Shelf, West Texas. We develop the integrated forecast models using a depositional energy index, a porosity index and a well spacing index. The depositional energy index is developed based on the idealized depositional sequences of the ramp and the shelf model. Normalization is used to define the porosity index and the well spacing index. A linear regression analysis is conducted on a data base to develop the integrated forecast models.
Use of Hydraulic Interwell Connectivity Concepts in Reservoir Characterization
Authors: Canas J. A. , Malik Z. A. , Wu C. H. 
Published: December 2007

ABSTRACT
This paper presents the use of hydraulic interwell connectivity concepts to characterize the reservoir for waterflood performance evaluation. These hydraulic interwell connectivity concepts are presented in terms of two indices: The Interwell Flow Capacity Index (IFCI) and the Hydraulic Interwell Connectivity Index (HICI). This approach utilizes the reservoir flow capacity and production/injection performance data to calculate the IFCI and HICI. The spatial distribution and correlations of these indices are useful to evaluate the reservoir characteristics for waterflood design and performance analysis. A Colombian (South America) sandstone reservoir in La Cira Field is used to illustrate the application of these concepts.
In Conflict: Marginal Reserves vs. Enforced Abandonment
Authors: Haynes C. D. 
Published: December 2007

ABSTRACT
The United States has become a nation of marginal oil and gas wells. Well abandonments have become commonplace, and each decline cycle in the price of oil and gas brings on a new round of well abandonments. Yet, we know that the majority of oil and gas resources in developed areas are still in the reservoirs. The plugging and abandonment (P&A) of oil and gas wells because of economic conditions is a byproduct of our market economy, and is a "fact of life" in our business. Typically, a well is abandoned because it has fallen below its economic limit, an arbitrary production rate depending, in part, on the present price of oil and gas.
Economic forces are not alone in dictating well abandonment. The timely abandonment of wells is prompted by state regulatory agencies, who must rigidly enforce abandonment statutes for environmental and bonding reasons.
The dilemma brought on by P&A is the damage usually done to the well which precludes inexpensive future access to the reservoir. This is mainly because of damage resulting from the salvaging of casing strings in the well at the time of abandonment. Most oil and gas producing states either allow or even require the recovery of casing during well abandonment. While of questionable economic value, this procedure is commonplace and virtually eliminates future reentry into the wellbore.
This paper discusses the rationale and economic considerations inherent in the P&A process. It suggests a means for regulating the abandonment of oil and gas wells without removing casing strings, while satisfying concerns of environmental damage downhole.
A Semi-Analytical Solution to Three-Dimensional Hydraulic Fracture Propagation in Multistress Media
Authors: Rueda J. I. , Rahim Zillur , Holditch S. A. 
Published: December 2007

abstract
Hydraulic fracturing plays a very important role in the enhancement of gas and oil production rates from low permeability reservoirs. To mathematically model a hydraulically induced fracture, one must couple equations describing formation elasticity, fracture fluid flow, and fracture mechanics. Also, the effects of fluid leakoff into the poro-elastic formation must be considered in association with the fracture fluid mass conservation equation. Fracture propagation models in multilayer systems are needed to better understand hydraulic fracturing and to optimize a fracture treatment design.
Currently, the determination of the optimum fracture treatment in formations of three or more layers are being carried out using pseudo three-dimensional or full three-dimensional fracture propagation models. Pseudo three-dimensional models usually run rapidly on personal computers. However, pseudo three-dimensional models are mainly applicable to fractures where the total fracture length is several times greater than the fracture height. If fracture height growth is a problem, full 3-D models are required to solve the fracture propagation problem rigorously. However, these sophisticated 3-D models require considerable computer memory, run time, and expertise by the user. Saving CPU time is very important in the optimization of the fracture design process because numerous fracture predictions and sensitivity analyses are needed to determine the optimum fracture design.
The objectives of this paper are (1) to develop an efficient three-dimensional, semi-analytical fracture propagation model that can be used to predict the created fracture dimensions and pressure inside the fracture for a given injected volume in a multilayer reservoir, and achieve results more compatible with a full 3-D model, and (2) to develop an accurate 3-D model that is easy to run and can execute rapidly on a personal computer.
In this research, We have developed a full 3-D fracture propagation model that allows us to compute efficiently the fluid pressures and fracture dimensions in a multilayer medium with asymmetric characteristics in each layer of rock. This model considers two-dimensional fluid flow inside the fracture and computes pressure drop in both directions of the fracture height and fracture length. We have used cubic polynomial approximations to represent both the fluid pressure and the in-situ stress profiles. Thus, we could use the analytical solution to determine displacements of an elliptical crack under arbitrary normal loading presented by Shah and Kobayashi1 (SK). We use the first variational technique to approximate certain partial differential equations. These equations are coupled with the analytical solution presented by SK1. As such, asymmetric fracture growth can be solved for a multilayer system, where each layer can have unique mechanical properties such Poisson's ratio, in-situ stress, Young's modulus, and fracture toughness.
A New Iterative Mathematical Model for the Analysis of Imbibition Carbonated Waterflood in Naturally Fractured Reservoirs
Authors: Shenawi S. H. , Wu C. H. , Jiang Chunhuan , Luan Z. A. 
Published: December 2007

ABSTRACT
A new semi-analytical mathematical model (IMOD) is developed as a part of a multidisciplinary study1-5 to investigate the potential of imbibition carbonated waterflood in low-permeability, naturally-fractured reservoirs. The model is based upon the concept of Buckley-Leverett type flow6,7 in a fracture surrounded by matrix blocks. The rate of water imbibition with varying water saturation at the imbibition boundary is represented by a convolution integral. The numerical iteration technique determines the fracture and matrix water saturation distributions in Laplace space. Stehfest's numerical Laplace inversion algorithm7 inverts the solutions to real domain.
Laboratory flow test data2,4 are used to check the validity of IMOD. Core face flushing technique is used in the imbibition experiments conducted on chalk cores. The test temperatures are 70 °F, 110 °F, and 150 °F. Concentrations of carbonated water solutions are 0.0, 2.3, 4.0 and 5.5 percent by weight of CO2, respectively.
The significant achievements of IMOD are: (1) it can provide the nonlinear solutions for a range of oil to water viscosity ratios and (2) the same model can be used for both plain and carbonated water imbibition recovery by adjusting the maximum recoverable oil (R∞) and imbibition recovery constant (λ). Results of the analysis show that: (1) the computed oil recoveries match the laboratory performance very well; (2) the computed oil recovery and phase saturation distribution in the fracture and matrix are greatly influenced by the magnitude of viscosity ratio; and (3) the imbibition recovery constant λ has a significant effect on the rate of imbibition oil recovery, thus, must be checked with laboratory data before modeling the reservoir performance.
Case History Analysis: Materials for Completion Equipment in CO2 Service
Authors: Chitwood G. B. , Coyle W. R. , Hilts R. L. 
Published: December 2007

Abstract
This paper presents two case histories from oil wells in the Middle East in which hardened and tempered alloy steel completion equipment underwent severe corrosion from CO2. The fact that in one case the API J-55 tubing string did not exhibit corrosion but did in another case indicates that corrosion in CO2 service can be influenced by several factors: the steel composition, its strength, or its heat treatment. A study was initiated to determine which properties or combination of properties should be altered to remedy the problem. Consideration was given to the use of different steels and/or heat treatments for completion equipment in order to achieve corrosion performance in CO2 environments similar to that of J-55 tubing.
It was determined that the alloy steel normally used for this equipment could not be reprocessed with heat treating to provide the needed corrosion resistance without a compromise of its metallurgical properties. This indicated a need to investigate alternative materials. The subsequent investigation of 9Cr-1Mo and 410 stainless steels found them to have superior corrosion resistance and good metallurgical properties. Therefore, these will be the materials of choice for completion equipment used to replace existing alloy steel equipment in these wells.
Miscible Displacement in Fractured Porous Media: Part I—Experiments
Authors: Firoozabadi Abbas , Markeset T. I. 
Published: December 2007

Abstract
Miscible displacement experiments were carried out in a number of matrix/fracture configurations. In all the experiments, fracture aperture was more than 150 microns, which exceeds field scale fracture thickness. Even with high fracture aperture, the miscible displacement process is shown to be very efficient. The injected fluid breaks through fast, but the injected solvent effluent concentration increases very slowly to about 1 PV injection. The results reveal that miscible displacement in fractured porous media can be a very efficient process.
A New Microbial Technology for Enhanced Oil Recovery and Sulfide Prevention and Reduction
Authors: Hitzman D. O. , Sperl G. T. 
Published: December 2007

Abstract
A new technology based on the existence and microbial utilization of the preformed volatile fatty acid content of the reservoir waters, prevents sulfate reduction by sulfate reducing bacteria by the competitive removal of the volatile fatty acids in the reservoir waters. A new microbial population is developed in the presence of nitrate which has the capabilities of producing in-situ products such as gases and polymers — all known recovery agents. Laboratory investigations demonstrate the versatility and potential of the system to alter microbial populations by subtle changes in the reservoir waters. Core flooding data show increased oil production. This novel approach to prevent and reduce sulfide while at the same time to increase oil recovery is termed "Biocompetitive Exclusion". A microbial liability in the field is turned to an advantage and offers the petroleum industry a low cost methodology for reservoir control and stimulation.
Rangely Weber Sand Unit CO2 Project Update: Decisions and Issues Facing a Maturing EOR Project
Authors: Masoner L. O. , Wackowski R. K. 
Published: December 2007

Abstract
The Rangely Weber Sand Unit (RWSU) CՕշ Project is juggling its maturing recovery performance against continued flat oil prices. The Unit's business goals of reducing operating cost per barrel of OEG production and maximizing net present value require improving the process efficiency. The recovery efficiency for the project initially improved, but has recently begun to decline as the CՕշ process matures. Achieving the business goals calls for identifying the key issues and decisions. Accomplishing this entails linking the recovery process and the business value measures. For this maturing CՕշ flood, the results indicate that the sweep efficiency defines the key decisions. Decisions that improve the sweep efficiency include water-alternating-gas management, workovers, pattern alignment, injected fluid apportionment, and field contraction.