bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effective Well and Reservoir Evaluation Without the Need for Well Pressure History
Authors: Poe B. D. 
Published: December 2007

Abstract
This paper presents a practical and useful analysis technique for effectively accomplishing a rigorous superposition-in-time (convolution) analysis of the transient drawdown performance of oil and gas wells that does not require that the flowing pressures (wellhead or bottom hole) be known for every flow rate data point in the production history. If at least one flowing pressure point is available at any point in time during the production history of the well, a unique analysis of the production data for the evaluation of the reservoir effective permeability, well drainage area, and well parameters such as unfractured well radial flow steady-state skin effect, fractured well effective fracture half-length and average fracture conductivity, or horizontal well effective length in the pay zone may be obtained. Even if no flowing pressures are available at all during the production history of the well, estimates of these well and reservoir parameters can still be obtained with reasonable accuracy using the analysis techniques presented in this paper.
The general evaluation procedures presented in this paper are applicable for all well types, including flowing wells and wells with artificial lift systems (i.e., conventional beam pumping units and electrical submersible pumps (ESP)). The theoretical basis for a rate-transient analysis of the production performance of a vertically fractured well is presented in detail in this paper. Application of the proposed general analysis procedure to other well types (unfractured vertical/slanted wells, horizontal wells, etc.) may also be found in a similar manner as presented in this paper. The theoretical basis for a pressure-transient based solution for a vertically fractured well is also available in the references.
In the relatively short period of time that this new analysis technique has been available, it has radically changed the way that engineers may now rigorously analyze the production performance of oil and gas wells to evaluate the well and reservoir properties from the well's production performance, as well as greatly expanding the number and types of wells that can now be considered. The new analysis techniques presented in this paper therefore represent a step-change in the petroleum industry's technical capabilities for the analysis of the production performance of oil and gas wells over that which existed prior to this work.
Application and Mechanism Studies of Clay Gum System
Authors: Wang Wei , Gu Yongan 
Published: December 2007

AbstractPolymer is used for mobility control in most chemical EOR projects. However, it is sometimes unfavorable because of its chemical and mechanical degradations and its high cost and investment risk. Efforts have to be made to develop a more effective and less expensive substitute for chemical EOR. This paper presents a clay gum system, which consists of montmorillonite, alkaline and a small amount of polymer. As a uniformly dispersed colloidal system with high viscosity, the clay gum system can be used as an oil displacement agent for mobility control in a heterogeneous reservoir. This system behaves as a pseudo-plastic fluid and has similar rheological property to a polymer solution. In addition to its insensitivity to salinity, it also shows a remarkable tolerance to strong mechanical shear and high reservoir temperature. The average enhanced recovery rates of the linear and radial coreflood tests for the clay gum system were found to be 35% and 10%, respectively. The microscopic oil displacement tests were conducted in transparent micromodels with rather different wettability to visualize the flow and adsorption processes of clay gum in porous media. Some major mechanisms of clay gum system were identified in the microscopic visualization tests. In particular, the colloidization process of clay gum can be explained in terms of the well-known DLVO theory. Furthermore, industrial pilot tests have been conducted in Gudong oil field and Shengcai oil field in China since 1992. The detailed pilot test results show that the clay gum system can greatly enhance oil recovery and effectively reduce water-cut. The pilot tests in these two oil fields had already produced over 12, 700 tons accumulative incremental oil by the end of 1998.
Non-Newtonian Fluid Flow in Coiled Tubing: Theoretical Analysis and Experimental Verification
Authors: Zhou Y. , Shah S. N. 
Published: December 2007

Abstract
This paper presents a comprehensive theoretical study of the flow of non-Newtonian fluid in coiled tubing using the boundary layer approximation method. First, a boundary layer approximation analysis was applied to the governing equations of continuity and motion of a power law fluid in the curved tubing flow geometry. Momentum integral equations for the boundary layer flow were then derived and solved numerically. The resulting solutions of the velocity field were used to develop a new friction factor correlation in terms of generalized Dean number, coiled tubing curvature ratio, and flow behavior index of the power law model. The new correlation of this study and a previous correlation by Mashelkar and Devarajan were evaluated using experimental data obtained from full-scale coiled tubing flow experiments. An excellent agreement was found between the new correlation and the experimental results. The Mashelkar and Devarajan correlation failed to result in any acceptable agreement with the experimental data, nor did it match the Ito correlation for the Newtonian fluids (n = 1). This work extends the range of applicability of the new correlation to fluids with flow behavior indices as low as 0.25, which would cover most fluids used for coiled tubing operations in the oil and gas industry.
Fast Induction Log Inversion Using Quasi-Newton Updates
Authors: Gao L. 
Published: December 2007

Abstract
Interpretation of induction logging data is difficult due to its diffusive nature and its large volume of investigation. To overcome these difficulties, various techniques have been applied in the past. These techniques include deconvolution filters, least-squares inversion, inversion based on the maximization of entropy, as well as neural networks techniques. Among them, the maximum entropy method is the most robust. Unfortunately, it is computationally intensive and can only be carried out in computing centers. To reduce this intensity and accelerate the inversion process, a new method has been developed for induction log inversion using quasi-Newton updates of the Jacobian matrix. Using the new method, 200 ft of log data can be inverted in 80 seconds on a notebook computer.
An Analytic Method for Producing Multiarray Induction Logs that are Free of Dip Effect
Authors: Barber T. D. , Minerbo G. N. 
Published: December 2007

Abstract
Dip effect on induction tool response is a well-documented and understood environmental effect that produces increased shoulder effect at moderate dip and a complete scrambling of multiarray induction logs at high dip. Although techniques such as maximum-entropy inversion allow a full correction of the logs, these remain computer-center products that are somewhat time consuming. Wellsite inversion to correct for dip effect has remained elusive, waiting on more computer power.
In the mid-1960s Pierre Grimaldi discovered an induction measurement technique that had the remarkable property of returning the same reading in a "thin" bed that it gave in an infinite, homogeneous medium of the same conductivity. The only requirement to satisfy this condition was that the instrument sensors were all in the thin bed. The instrument configuration was such that the voltage measured was a direct solution to Maxwell's equations. Although this was a breakthrough, the instrument configuration was difficult to realize in hardware, particularly with the well-logging technology of the 1960s, and the idea was never published.
The Grimaldi configuration was independently rediscovered in the early 1980s and studied with new modeling codes. It was found that the "remarkable property" of having no shoulder effect was also approximately true at any dip angle. Again, the hardware was deemed to be impractical.
More recently, it was discovered that the array configuration of the AIT* Array Induction Imager family of tools was such that the raw array measurements data could be processed to be the same as from a Grimaldi configuration. This led to a real-time algorithm, and a set of Grimaldi curves is now available at the wellsite. This algorithm produces synthetic arrays equivalent to a Grimaldi coil configuration that solve the inverse problem without having to solve Maxwell's equations iteratively.
The Grimaldi configuration is not without its drawbacks. The logs have a shallower depth of investigation than those from a conventional induction array of the same spacing. For this reason the Grimaldi logs supplement, but do not replace, the standard AIT log sets.
Performance of IMPSAT and IMPSAT-AIM Models in Compositional Simulation
Authors: Cao Hui , Aziz Khalid 
Published: December 2007

Abstract
The current trend in industry is to use finer and finer grid with larger and larger number of components. This requires the development of faster simulation techniques than those currently available in commercial simulators.
The fully implicit (FIM) model, the implicit pressure and explicit saturations (IMPES) model and the adaptive implicit (AIM) model are the traditional approaches. The IMPSAT (implicit pressure and saturations and explicit component mole fractions) model has been proposed in the literatures, but so far it is not considered a viable approach. This may be a result of lack of suitable stability analysis and improper implementation. Our analysis shows that the IMPSAT model is significantly more stable than the IMPES model, and in many cases substantially less expensive than the FIM model. The IMPSAT model becomes particularly attractive as the number of components becomes large. IMPSAT can also be used in an adaptive implicit approach to form various IMPSAT based adaptive implicit (IMPSAT-AIM) models.
A new General Purpose Research Simulator (GPRS) using a General Formulation Approach has been developed and tested. The General Formulation Approach used in GPRS can be used to obtain any type of model. We can easily form a model by selecting any reasonable set of primary variables and any level of implicitness from IMPES to FIM. One important subset of models that have been developed from this new approach is the IMPSAT model and the IMPSAT based AIM models.
The performance of different compositional models has been evaluated using a wide range of problems. We found that the IMPSAT model and the IMPSAT-AIM models have very good performance, and they are more efficient than the traditional models (FIM, IMPES and AIM). The IMPSAT model is generally over 50% faster than the IMPES model due to its improved stability. For problems that are not very hard, the IMPSAT model is cheaper to run than the FIM model since it reduces the number of unknowns that have to be solved implicitly. The IMPSAT-AIM models are more flexible, more stable and with appropriate linear solvers have the potential to be less expensive in terms of CPU time than the traditional AIM model.
Process-Based Decomposition on Distributed Systems – A Strategy to Solve Large Scale Simulation Problems
Authors: Yu Mengjiao , Gadde Phani B. , Sharma Mukul M. 
Published: December 2007

AbstractLarge-scale simulation problems have extremely large CPU and memory requirements. Traditional methods for solving such problems involve parallel processing, which adds cost and complexity in programming. We propose a novel process based decomposition approach for distributed processing of such large-scale simulation problems. The proposed method splits up the large-scale problem based on the physics or computational units of the problem and distributes the computational load over a LAN. This method allows the problem to be solved in parallel in a distributed framework in a computationally efficient manner. The greatest advantage of this approach is that this method allows performance enhancement at little extra cost by better utilizing existing computational resources (CPU cycles). Based on the complexity of the decomposition, we categorize large-scale simulation processes into three classes. We present a distributed processor (OPTIMA) that enables application programs to be run in a distributed framework. Examples that demonstrate the efficacy of this method are presented. Results show that running the simulations in parallel on a distributed platform speeds up the process considerably with small hardware or software costs.
A Novel Approach to Gas Lift Design for 40,000 BPD Subsea Producers
Authors: Duncan G. J. , Beldring B. 
Published: December 2007

Abstract
Gas lift in Terra Nova production wells serves two purposes. The first is to increase the rate at which reservoir fluids can be produced, especially as water cuts increase with time and reservoir pressure diminishes. The second is to stabilize flow in the wells, flowlines and flexible risers. This paper describes the application of engineering tools to achieve an optimized subsea gas lift design for a 6350 m3/d (40,000 bpd) production rate, taking into account reservoir, wellbore, subsea and topsides constraints.
A Real Options Model for Portfolio Selection of Oil and Gas Assets
Authors: Lima Gabriel A. C. , Suslick Saul B. 
Published: December 2007

Abstract
Portfolio selection of oil and gas assets is a fundamental subject of capital budgeting in the energy sector. Traditional methods of portfolio selection are index ranking, zero-one programming, and utility functions. However, none of these methods mentions the value of option timing when the firm is selecting the desired combination of projects. This paper compares results of portfolio selection of non-developed reserves using both traditional approaches and option timing.
Monitoring Fracturing Fluid Flowback with Chemical Tracers: A Field Case Study
Authors: Asadi Mahmoud , Woodroof Robert W. , Malone William S. , Shaw Donald R. 
Published: December 2007

Abstract
Proper fluid and proppant placement is the key to a successful fracture simulation. Performance of fracturing fluids, as they are pumped into a fracture, is the key to effective proppant placement. Fracturing fluids are used to both prop open a fracture and to effectively carry the proppants and place them into a fracture and to successfully flowback to the surface. Productivity of a well, after proppant placement, greatly depends on the flowback efficiency. This paper presents a novel technique where fracturing fluid flowback can be effectively monitored in a complex multi-zone fracture system. A family of environmentally safe chemical frac tracers, with unique characteristics, is developed to assure distinction of each zonal frac fluid upon flowback. The paper also presents a case where the technique was implemented in a multi-stage-fracturing job. Various chemical frac tracers were injected during different stages, which included pad fluid and crosslinked fluid with various proppant concentrations and breaker loading. Results and fracture flowback diagnoses are presented.
Cement Pulsation Treatment in Wells
Authors: Wojtanowicz Andrew K. , Smith John Rogers , Novakovic Djuro , Chimmalgi V. S. , Newman Ken R. , Dusterhoft Dale , Gahan Brian 
Published: December 2007

Abstract
Cement pulsation is a novel technology for enhancing zonal isolation by applying low frequency, hydraulic, pressure pulses to the wellhead immediately after cementing. The treatment maintains the slurry in a liquid state, which transmits hydrostatic pressure downhole, and keeps the well overbalanced thus preventing early gas flow after cementing.
The paper summarizes several stages in the development of cement pulsation technology including comparison to other methods, physical principles, process analysis, mathematical modeling, computer-aided design, laboratory testing, and field performance.
The paper supports published information on cement pulsation with data from research and field studies that was instrumental in developing the technology. Emphasis has been given to the analysis of the pulsation process, description of design model and software, and an updated account of field applications.
Described is the MS Windows software for pulsation design. Two examples demonstrate the computer-aided design. The examples show that the software could be used to find the pulse size and treatment duration for a constantpressure treatment. Alternatively, a variable-pressure treatment with controlled treatment depth could be designed.
Data is presented from pulsation of over 80 wells in drilling areas notorious for early gas migration after cementing. Field applications of the technology in 80 wells provided significant evidence of the success of cement pulsation in preventing early gas leakeage in cemented wells.
Subsea Remedial Cementing of Conductors on Template-Drilled Development Wells
Authors: Reynolds D. A. , Hannestad E. , Melchiorsen J. C. , Morrison G. G. 
Published: December 2007

Abstract
All operators face a number of well design decisions throughout the planning and execution of a development project. Decisions based on preliminary data can subsequently turn out to be sub-optimal leading to significant problems developing after there is no straightforward way of preventing these from escalating. This paper describes how a significant structural risk evolved with the conductors in several wells of a development with no obvious method to prevent continued deterioration. It describes how a new and innovative set of equipment, known as the Annular Sealing Unit (ASU) was designed, built, tested and deployed offshore to restore the structural capability of the wells without any production or operational shutdowns occurring.
Further, it describes the details of the planning and execution of the ASU project. Lessons learned during the project will highlight how the close co-operation between the operator and service provider was fundamental in leading to the success of the project.
The experience gained from this project has demonstrated that although a significant challenge can present itself with no initial straightforward solution(s) apparent it is possible, with clearly defined roles and an open and innovative approach to the challenge, to identify and implement a new process and solve the problem in an inventive way.
Finally, this paper recognises the initial shortcomings in the development's conductor setting procedure. Although it may appear obvious with hindsight to the reader these were not apparent until well into the development and can act as a cautionary narrative as to how a fundamental well planning decision can have a far-reaching and adverse effect.
Value Created Through Versatile Additive Technology and Innovation for Zonal Isolation in Deepwater Environments
Authors: Reddy B. R. , Richard Vargo , Sepulvado Bob , Weisinger Don 
Published: December 2007

Abstract
Value may be created by applying innovative technology in challenging zonal isolation applications. Risk evaluation in deepwater cementing can be accomplished without jeopardizing environmental impact and cost effectiveness. Some of the highest risks encountered in deepwater cementing operations are related to low temperatures and the existence of shallow water flows (SWF). Generally, for cementing low-temperature zones, high early strength blends with set accelerators are utilized. At normal temperatures, Class A or Class H Portland cements are normally preferred in Gulf of Mexico (GOM) operations. The cement system for SWF zones should have a relatively low density and a short transition time to help maintain well control. Presented in this paper are examples of how a single cement system has been used to meet all design criteria for delivery of deepwater well cementing.
A disadvantage in using a variety of cement types and blends for cementing in an offshore environment is that the unused preblended materials designed for a given depth are often discarded, and new blends are made up for the subsequent cementing operations. This can result in increased material costs and repeated trips to shore. It is desirable, both economically and environmentally, for an operator to be able to use the same neat cement for cementing wells at multiple depths.
This paper presents details of an innovation that involves cementing offshore wells with SWF problems with only one neat cement by using versatile additive technology. Case histories for cementing several wells in the GOM in water depths greater than 2,000 ft are presented. In all cases, flowable salt-water zones were encountered while drilling. The operator's risk assessment of the problem was uncertain at the time of well design and planning because of the exploratory nature of the wells drilled. The liquid additive system for flow control gave the operator the flexibility of having the additives on the rig at the time the holes were drilled. The operator could evaluate the flow potential before deciding to use the system or use other options.
The foamed cement system used in these case studies used a liquid additive for SWF control. The remaining portions of the wells were cemented with the same neat cement by using different liquid additives. This in turn helped reduce environmental impact of wasted cement and saved the operator considerable capital for the wells drilled.