bluuebunny/crossref_metadata_2025_split huggingface dataset:
Use of a Pseudosteady-State Solution to Predict Productivity of a Fractured Well with Spatially Varying Fracture Geometry
Authors: Lee Kun Sang 
Published: December 2007

Abstract
An infinite- or finite-conductivity vertical fracture intersecting a well produced at a constant rate within a closed system is considered. Fracture is modeled as a vertical slab with lengthwise variation in the fracture geometric properties. The long-time inflow performance is obtained from a finite-element solutions of pseudosteady-state diffusivity equation, which considers fixed flux over all reservoir region.
The first part of this paper examines the behavior of an infinite-conductivity fracture. Comparisons of well productivity calculated with transient and pseudosteady-state solutions show a good agreement. Computations for anisotropic reservoirs were made to examine the effects of reservoir permeability anisotropy and fracture length on the late-time pressure response. It is demonstrated that well productivity is heavily dependent on the fracture orientation and main flow pattern. The second part investigates the effects of fracture permeability on the pressure response of a finite-conductivity fracture. The fracture conductivity is a decreasing function of distance from wellbore.
The new fracture model and solution technique provides more realistic description for fracture geometry and long-time pressure response with a minimum computational effort.
Fluid Diversion to Improve Well Stimulation
Authors: Gallus Julius Peter , Pye David Stephen 
Published: December 2007

Abstract
A review of diverting is made with primary emphasis on granular diverting agents, and wax-polymer diverting agents in particular. The results of laboratory tests are given. Numerous field tests are reviewed, including we!! production data. Both the laboratory and field tests production data. Both the laboratory and field tests show the wax-polymer agents to be the best of the diverting materials tested. The wax-polymer materials are also oil soluble, which will prevent formation damage.

Introduction
Designing treatments for the stimulation of low-productivity oil and gas wells by acidizing, hydraulic fracturing, and injecting organic solvents or surface-active chemicals is an important function of the modern petroleum engineer. These well-treating processes are well established today. However, in many cases achieved success ratios leave much to be desired. Analysis of job failures shows that all too frequently failure may be attributed to poor treating-fluid distribution. Failure to effectively divert treating fluids from thief zones results either in no treatment or poor treatment of the producing interval.
Thief zones can result from any number of causes, a principal one being nonhomogeneous formations. Producing principal one being nonhomogeneous formations. Producing formations penetrated by oil and gas wells range from 3 to 3000 feet in thickness. As a rule these zones are profoundly inhomogeneous, discontinuous and variable in profoundly inhomogeneous, discontinuous and variable in permeability, sometimes from centimeter to centimeter. permeability, sometimes from centimeter to centimeter. Fluid flow surveys within wells have shown that production from and injection into permeable zones frequently occur in only 10% to 15% of the productive interval. Besides inhomogeneities, variable flow potentials can also be caused by damage to part of the formation. In view of what is known about formation and perforation damage, this is not too surprising.
Productive formations, particularly sandstone formations, act essentially as filters. We know that filters become plugged with time, and we expect them to become plugged, it would appear reasonable to say that we should similarly expect formation rock to decrease in permeability as large volumes of crude oil and brine permeability as large volumes of crude oil and brine which carry solids are filtered through it into the wellbore.
Performance Evaluation And Formation Damage Potential Of New Water Based Drilling Formulations
Authors: Argillier J-F. , Audibert A. , Longeron D. 
Published: December 2007

Abstract
Water based drilling fluid formulations have been recently adapted to new drilling technologies and environmental concerns. This involves selection of specific additives that prevent problems encountered when drilling slimhole, high temperature wells or inactive clayey formations. Formation damage risks are well documented for standard mud formulations but they are poorly analysed for new types of non polluting muds. This paper describes extensive laboratory work aimed at evaluating the behavior of these new types of mud formulations. First, static and dynamic filtration experiments were conducted on paper filters and rock slices. Examination of mud cakes by means of cryo-SEM has permitted to correlate filtration behavior with structural characteristics of both external and internal mud cakes. Then, the simulation of the full process of mud invasion in oil-bearing reservoirs was achieved by performing static and dynamic filtration experiments in a specially designed core-holder cell containing 40 cm long sandstone core samples. Cumulative filtrate losses and pressure drops across six sections of the core while circulating the mud and back flushing the oil were continuously monitored to evaluate the permeability damage. Damage arising from overbalanced conditions has been evaluated in terms of cake permeability, fluid loss characterization, reduction in oil permeability after mud exposure. For the three mud compositions tested here the filtration process in high permeability sandstones is mainly controlled by external mud cakes. Damage is severe but an additional damage due to the trapped aqueous filtrate phase can strongly affect the oil relative permeabilities. This approach has given a complete behavior understanding of new water based drilling formulations including evaluation of their performances, limits of use at high temperature and assessment of risks for different operational conditions.
Development of a Recommended Practice for Formation Damage Testing
Authors: Marshall David S. , Gray Russell , Byrne Michael 
Published: December 2007

Abstract
Well productivity can be significantly affected by damage to the near well-bore area caused during drilling in the reservoir section of a well. Historically, the use of perforated completions allowed for penetration of the producing formation beyond the damaged area but the recent trend towards non-perforated completions has resulted in an increased emphasis on damage minimisation. This, in turn, has increased the importance of evaluating drilling fluids and completion techniques used from a reservoir damage perspective. The suitability of a drilling or completion fluid for use in a particular reservoir can, and should, be determined using the measurement of return permeability or some other indication of formation damage. A major factor which limits this practice is that no industry standard equipment or methodology exists for this type of testing and differences in results obtained at different times or in different laboratories cannot be reliably compared. Repeatability and reproducibility of the tests conducted have not been widely established. In order to address these problems, a recommended practice for formation damage testing has been developed which covers all aspects of the test methodology from core selection and preparation to the writing of the final report and interpretation of the results. By standardising on equipment and methodology, it has been possible to establish the degree of variation which can be expected when the same samples are tested in the same way in different laboratories. Further testing in which selected parameters have been varied has also given an indication of the degree to which the setting of these variables affects the final result. It is hoped that this recommended practice will now gain acceptance throughout the industry and that the process of evaluating fluids for formation damage potential will become simpler and more efficient through tie greater use and validity of comparisons between data from different sources.
Biotechnological Treatment Removes Xanthan-Based Skin Damage
Authors: TjonJoePin Robert M. , Beall Brian B. , Brannon Harold D. 
Published: December 2007

Abstract
Conventional reservoir drilling fluids typically consist of xanthan-based polymers to optimize recovery of drill cuttings and reduce friction or torque during the drilling operations. Previously conducted laboratory studies have indicated that the damage produced by these types of xanthan-based drilling fluids can be easily removed. Field data, on the other hand, has indicated that substantial amounts of polymeric damage remain in the formation. Even though these psuedoplastic, non-thixotropic, xanthan-based drilling fluids exhibit low shear rheologies during the operations, they can contribute to tremendous amounts of skin damage. This insufficient degradation of filter cake may impede flow and dramatically reduce formation permeability hence well productivity.
Recent extensive research was conducted to develop a treatment which could effectively reduce this type of polymeric damage. A novel biotechnological treatment has been developed, which effectively removes xanthan-based filter cakes or skin damage at temperatures from 70 °F to well over 250 °F.
Core flow evaluations have shown that multi-fold improvements are achieved with this optimized biotechnological removal treatment. A detailed study of the laboratory and field case histories are presented. Average incremental production rates of the treated wells were significantly improved, clearly demonstrating the effectiveness of this removal system.
Revolutionary New Chemical Delivery System for Fractured, Gravel Packed and Prepacked Screen Wells
Authors: Webb P.J.C. , Nistad T.A. , Knapstad B. , Ravenscroft P.D. , Collins I.R. 
Published: December 2007

Abstract
Laboratory tests and a field trial have demonstrated the technical and economic benefits of a revolutionary downhole chemical scale inhibitor delivery method. The method also has the potential to be used for other oilfield chemicals, for example corrosion inhibitors and gel breakers.
The method involves the controlled release of chemical from impregnated porous ceramic beads, manufactured with the necessary mechanical strength and size properties for direct substitution of proppant, gravel pack sand and prepacked screen beads.
This novel concept offers an economically attractive method of chemical delivery for both advanced wells and conventional wells when compared to conventional intervention based delivery techniques, such as squeeze treatments. The concept addresses many of the operational problems associated with chemical treatment of wells completed with multiple fractures, long horizontal sections with unfavourable pressure regimes, remote wells with high intervention costs, and multi-lateral type completions. In general, the concept offers reduced deferred oil costs through reduced well intervention and preservation of pack conductivity, and more efficient chemical use compared to squeeze technology.
Wells with fractures containing in excess of 100,000 lb of proppant have the potential for scale inhibitor treatments lasting a significant proportion of a wells lifetime. Prepacked screens containing 3,000 lb of chemically impregnated bead could provide treatment periods of 2 to 36 months.

Introduction
The deposition of mineral scales, such as carbonates and sulphates, in oil producing wells is a recurring operational problem for conventional and advanced wells. Significant operational costs are incurred when applying preventative or remedial scale control strategies, for example chemical scale inhibitor squeeze treatments or re-perforation, respectively. This paper presents technical and economic details of a revolutionary method of scale inhibitor delivery developed by AEA Technology with the support of Saga Petroleum ASA, Norsk Hydro ASA, and BP Exploration Operating Company Ltd. The delivery concept has many advantages when compared to conventional scale control strategies, as applied to advanced and conventional well completions. The potential for applying other chemical types is briefly discussed. The method of delivery is applicable to production wells completed with propped fractures, gravel packs, prepacked screens, and other intermediate types where beads or proppant are placed in a well.
Use of a Simple Mathematical Model for Estimating Formation Damage in Wells Intersecting Long Fractures
Authors: Guo B. , Schechter D. S. 
Published: December 2007

Abstract
A newly developed mathematical model has been used for formation damage analyses of two hydraulically fractured horizontal wells in the Daqing field, China, and twelve vertical wells in the naturally fractured reservoirs of the Spraberry Trend Area, West Texas. Application of the model to Daqing horizontal wells indicated that these wells should have 4 to 5 times higher oil production rates if the formation was not damaged. The use of the model has captured the characteristics of rapid decline in productivity of the Spraberry vertical wells. Comparisons between the effects of matrix skin and fracture permeability indicated that stress-sensitive fracture permeability is responsible for the productivity loss of these wells. This paper provides reservoir engineers with a practical tool for analyzing inflow performance of wells intersecting long fractures.
A Novel Dual Injection System for Water Shut-Off Treatments
Authors: Plahn S.V. , Stevens D.G. , Enkababian P.G. , Anyan S.L. , Feraud J.P. 
Published: December 2007

Abstract
There are numerous water shut-off techniques available. One of these is to permanently seal watered-out zones with rigid, polymer gelants. This method can be very effective for near-wellbore water flow problems provided the gelant only enters the watered-out interval and does not damage nearby productive pay. Gelant placement can frequently be controlled using mechanical devices such as packers and bridge plugs. However, many times, gelant may still enter productive pay through flow paths outside the casing. For such cases, mechanical isolation within the well may not suffice - especially if crossflow between zones is high. In this paper we discuss a specialized gelant placement technique, referred to as dual injection, that can be used to address these types of water control problems. Dual injection can be implemented several ways. We discuss some of these, as well as a completely new dual injection system.

Introduction
Numerous techniques exist for solving water production problems. These range from simple mechanical means such as bridge plugs and casing patches, to more elaborate schemes involving downhole separation, dual production, and horizontal drilling. Injection of polymer gelants is also a widespread practice.
Polymer gelants can be deployed a variety of ways. By far the most pervasive is to pump down the existing production tubing without any zonal selectivity (viz., "bullheading"). This procedure is operationally attractive because it is easy to implement and treatment costs are comparatively low. However, gelant is distributed among all perforated zones. This is undesirable because many gelants - particularly those intended for near-wellbore applications - will indiscriminately and permanently damage all porous media when gelation or setting occurs.
Mechanical isolation of perforated intervals with packers and bridge plugs, or sand/calcium carbonate fill is preferred over bullheading. Often however, flow can still occur between perforated intervals through flow paths outside the casing. In such cases, mechanical isolation may not suffice. In this paper we will discuss a specialized placement technique, referred to as dual injection, that can be used to address water control problems in such cases.
Water Control by Bridging Colloids
Authors: Zitha Pacelli L. J. 
Published: December 2007

Abstract
This study explores the potential of dual polymer-colloid systems to improve polymer placement. The approach consists of an analysis of microscopic flow aspects. We show that dual bridging adsorption of polymer-colloids may occur similarly to that of polymers alone. However, in the former case, the ensuing permeability reduction is much stronger. Therefore, dual polymer-colloid adsorption may improve considerably polymer placement.
Field Testing A Front-Mounted Mechanical Oilfield Pumping Unit
Authors: Byrd J.P. , Jackson B.C. 
Published: December 2007

Publication Rights Reserved
Discussion of this paper is invited. Three copies of any discussion should be sent to the Society of Petroleum Engineers office. Such discussion may be presented at the above meeting and considered for publication in one of the two SPE magazines with the paper.

Abstract
Several major oil companies have made recent, head-to-head studies comparing the mechanical properties of a front-mounted, non-symmetrical mechanical pumping unit to those of its well known conventional counterpart. The results of there tests have shown that in many applications, the lower torsional and structural loading of the front-mounted unit allows the operator to use smaller and less expensive equipment to handle the same fluid loads. This paper includes one of these recent, representative, oil company studies and its conclusions.
During the latter part of 1956, a front-mounted, non-symmetrical, mechanical beam-type pumping unit was developed for general oilfield service. This machine was designed for the same wide range of application covered by the standard or conventional surface pumping unit. Although this new pumping system employed the same general structural components, its mechanical characteristics, and hence, its functional ability, were substantially different from those of the conventional unit.
The difference in the mechanical properties of the new machine was produced by a re-arrangement of the components of the conventional unit. This changed it from a symmetrical Class I lever system [fulcrum at mid-beam] to a non-symmetrical Class III lever system [fulcrum at rear beam]. The well load and counterbalance torque were dephased by providing an angular off-set in the crank, and moving the gearbox away from the well a proportionate amount, while driving the machine in a particular direction of rotation.
This front-mounted [Class III lever] unit [Fig. 1] combines the simplicity, ruggedness, and high efficiency of the conventional unit, with the beneficial rod motion and ease of counter-balance of the air balanced system, and provides, in addition, a relatively uniform torque demand on both primer mover and gear reducer.
This new Class III geometry makes possible several desirable pumping unit properties:A simple means of presenting the normal rod load variation of each pump stroke as a relatively uniform torsional load to both gear reducer and prime mover. By smoothing out these peak torsional loads it is often possible to use a smaller gear reducer and prime mover to handle a given application.A method of lifting rods and fluid with lover upstroke acceleration so that in many cases the peak polished rod load is appreciably reduced. This property not only tends to minimize rod loading but it also tends to minimize production losses because of reduced rod maintenance.
A Predictive Method to Estimate Remaining Gas Reserves and Future Prospect Outcome Probabilities
Authors: Zorbalas K. , Rogers R. E. 
Published: December 2007

Abstract
In trying economic times when exploration budgets are cut, a partially explored basin can experience a slowdown in activity, leaving us questioning whether sufficient reserves remain to justify further exploration.
In such situations a clear idea of the basin's potential is necessary in order to continue drilling new wells. A series of studies was undertaken and probability plotting was used to analyze the Black Warrior basin of Mississippi for the number and size distribution of undiscovered natural gas reserves.
Part of the study was the use of decline curve analysis to predict ultimate gas reserves from 256 active wells in the basin. A recovery factor as a function of depth for the Warrior gas fields was developed. Original gas in place figures were calculated using the recovery factors and the predictions of ultimate reserves. It was found that the ultimate reserves by field in the Black Warrior basin are log-normally distributed.
By using probability plots in any partially explored basin, one can foresee the economic justification for further exploratory drilling. This method is the most thorough and informative technique that can be applied to a basin which has a proven potential of future discoveries. As exploration becomes more selective, this technique could become a valuable tool to many exploration programs.
Argentine Gas and Electricity markets - Energetic Integration in South America
Authors: Markous Ricardo M. , Ridelener Daniel A. 
Published: December 2007

Argentine Gas and Electricity markets - Energetic Integration in South America.

Abstract
This paper is aimed at showing the favorable conditions of the argentine energetic market with respect to exports. Both the electric and gas markets are analyzed after the significant changes they have undergone since 1991/1992. And finally we analyze, the chance of an energetic integration and the information about several projects under study.

Introduction
1991 was a year of essential changes in the electric market. A mainly state owned centralized management of generation resources switched to an open regulation system divided into three basic areas: generation, transmission and distribution; the subsequent deregulation of the first of these areas created competitive conditions within the electric industry. Additionally several effects are having a great impact in the development of the electric market:–Due to the absence of the state as an investor and to the remarkably high investment costs required to face hydroelectric projects, apart from Yacyreta, there are no significant projects in the market,–The contracts granted in the privatization of the big Power plants turned out to be an uncertainty factor as regards their expiration. Thus, generators face two alternatives: either they re-equip to be able to achieve an efficient competition level or they run the risk of being left out of the market.–There is an important fall in gas turbines and combined cycle units prices.
A similar analysis can be made of the gas industry. Before the privatization of Gas del Estado, Argentina's state owned gas transportation and distribution company, the gas pipelines in the country worked with a high load factor. New transportation capacity was available just to supply Residential peak demand, fact which was not always achieved. Out of the winter period, idle capacity was used to supply power plants.
As from 1993 and specially during 1994 and 1995 there was a significant increase in transportation capacity, mainly due to the obligation of the distribution companies to supply their non-interruptible customer, to keep minimum standards of service, and to the demand of industrial consumers and power plants for "no-cut off" firm capacity.
This resulted in a significant increase in transportation capacity, a lower load factor, and more availability of gas for the electric industry.
We should also underline that since May 1994, the price of gas at well-head was deregulated, encouraging the search and development of new reserves.
The first part of this paper will show in detail the growth of the electric market, the higher availability of gas for it, how some of the above mentioned issues interrelate and the effect that competition in the electric market will have in the coming years.
The second part of this paper analyses the possible energy complementation among the Southern Cone countries, and the advantages of some of the integration projects currently under way.