bluuebunny/crossref_metadata_2025_split huggingface dataset:
Identification, Origin, and Distribution of Tarmats in Upper Zubair Sand Reservoir, Raudhatain Field, North Kuwait
Authors: Azim Shaikh Abdul , Al-Anzi Salah , Hassan Yahya , James Stephen , Mandal D. , Al-Ajmi Hamad 
Published: December 2007

AbstractThe Upper Zubair Formation is a giant reservoir consisting of 350 ft of excellent quality sandstone. This main producing reservoir has a 100 thick tar mat historically encountered near oil water contact. Recently, a well completed in the crestal part of structure above tar mat zone and in good quality sand did not contribute to oil production and presence of tar was suspected. A re-look at identification, origin and distribution of the tar mat has become critical for formulating future development strategy of the reservoir.An appraisal well was drilled on the crest with a comprehensive data acquisition program including coring, fluid sampling and logging. Geochemical analyses of core plugs at every 4 ft were carried out along with fluid invasion studies. Observation from core material was compared with NMR logs to formulate criteria for identification of tar zones to supplement information from open hole and cased hole logs.NMR transverse T2 relaxation histogram was observed to be affected by fluid properties and poresize distribution. There is a consistent shortened T2 distribution along tar mats resulting in missing porosity compared to neutron-density derived porosity. Geochemical analyses of core material indicates high asphaltene zones having undegraded paraffin and are isotopically lighter with immature biomarkers and higher concentration of aromatics. The observations indicate early origin of tarmats due to biodegradation of immature oil at a lower reservoir temperature. Later, undegraded oil with undegraded paraffin profile has migrated in to the reservoir after biodegradation process has ceased.Biodegraded early origin of tarmat can not explain areal distribution over the field. Local compartmentalization of tar mat from light oil leaking along faults leaving behind heavier fractions during geological history is the possible origin for tar occurring above tar window. Early high Asphaltene content from immature charge, Asphaltene precipitation due to later light oil migrating to trap and gravity segregation explains the occurrence of tarmat in tar window near oil water contact. Early charges/asphaltenes were bio-degraded and incorporated in the tar zone.Current study helps in identifying and mapping the tar and heavy oil zones in the reservoir. Distribution of tar mat of diverse origin needs to be understood well in advance to have realistic estimation of movable hydrocarbon.
From Justification to Selection: An Automated Supervisory System for the East Vacuum Grayburg-San Andres Unit
Authors: Krusen Leslie C. 
Published: December 2007

ABSTRACT
Phillips Petroleum Company, as operator for the East Vacuum Grayburg-San Andres Unit, has included an innovative automated supervisory system in the unit's development plan. The system, featuring redundant minicomputers, approximately 200 microprocessor-based RTU's, UHF-radio communications, automatic well testing, and local pumpoff and injection controllers, will increase Unit profitability by improving operation and management of the enhanced recovery project.
Since supervisory systems are a relatively new form of production technology, considerable attention was given to economic justification. After the state of the art was surveyed, constraints upon the system and system functions were determined. The supervisory system was then conceived of as four subsystems; wellsite, satellite, central battery, and command; related both to the production equipment that was to be monitored and the information that was required. The system was let, with installation scheduled for second-half 1981. This paper describes Phillips' path, from supervisory system justification to selection, as a guide to other operators who are considering such a system.
Some of the system's pumpoff controllers, injection controllers, and well test panels have already been installed. Preliminary results are encouraging, although there have been unexpected problems that are currently being resolved. Both are presented, to provide other operators with the benefit of Phillips' present experience.
Performance Resolution Between Variant Rock Bits From Field Drilling Data
Authors: Newcomb Alan L. 
Published: December 2007

ABSTRACT
Rock bit development projects require reliable techniques for evaluating field test data. Differences in performance are determined by using comparison methods in combination with criteria for data acceptance. The main objective is to field test an experimental feature involving the cutting structure, seals, lubricant or bearing of a rock bit and determine its related improvement in drilling performance. Drilling performance is defined in terms of drilling duration and rate of penetration. Performance resolution of small differences relies on the use of simple statistics and rock drillability methods to interpret the test results. These test results form a decision basis for incorporating the experimental feature into the product.
Analysis and Design of a Deep Reservoir, High Volume Nitrogen Injection Project in the R-1 Sand, Lake Barre Field
Authors: Haag James W. 
Published: December 2007

ABSTRACT
An expansion of a low volume gas injection project in the R-1 Sand, Segment G in the Lake Barre Field was investigated. Computer modeling shows that over five million barrels of oil can be produced. Challenges to project startup include drilling and reworking deep wells and the acquisition of a high pressure nitrogen source built on a semisubmersible concrete barge.
Preventing Mud Losses by Wellbore Strengthening
Authors: Song Jae H. , Rojas Juan C. 
Published: December 2007

Abstract
Until recently, the drilling industry had an established range of options for dealing with lost circulation that included pre-treatment with lost circulation material (LCM) and/or remediation with LCM when losses occurred. This paper describes a fully engineered approach taken by BP and Halliburton to formulate a drilling fluid that can effectively strengthen the weak wellbore while drilling. The approach, called Stress Cage theory, is an extension of a lost circulation strategy that has been used for years in the drilling industry. However, it includes using log analysis to identify potential fracture location and determine its geometry, especially its width, and then identify a mixture of particulate materials to seal the calculated fracture width. The application of the appropriate mixture of materials can effectively increase fracture gradient (both in land and offshore), allowing the operator to drill through a weak formation pressured zone successfully with minimal to zero downhole losses. Case histories including drilling parameters, formation pressures, field and laboratory fluids testing, and some of the operational challenges are detailed. The estimated value of Stress Cage applications for BP in 2004 and 2005 has been calculated at $100MM.
Simulation of Gas/Oil Displacements in Vuggy and Fractured Reservoirs
Authors: Kossack C. A. 
Published: December 2007

AbstractThe presence of vugs in a naturally fractured reservoir can be a significant source of reserves. These vugs can be connected to the fracture system or be isolated in matrix material which constitutes a triple porosity system. The modeling of the displacement of oil from the vugs can not be made with conventional dual porosity reservoir simulators since triple porosity system "isolated vugs" are not part of the formulation.The simulation of oil production from triple porosity reservoirs requires the development of composite porosity, composite relative permeabilities and composite capillary pressure relationships. These composite curves can be generated from properly designed laboratory experiments on representative cores or by history matching fine grid single porosity simulations. Kossack, et al1 discussed this for water-oil systems. Since the displacement of oil from vugs by gas involves very different mechanisms from water-oil systems and is very complex, the simulation of this process must be studied separately.This paper describes a numerical scale-up technique to provide the composite properties and curves to be used in gas-oil displacements in triple porosity systems. Displacements in dual and triple porosity gas-oil systems are dependent on the magnitude of gravity and viscous forces, capillary pressure in the matrix rock, composition of the injection gas, and rate of component diffusion in the porous media. Fine grid single porosity simulations are made with a compositional simulator to determine the rate of oil recovery from the fractures, matrix rock, and vugs. These results are then matched with dual porosity compositional simulations, which create the composite matrix properties.These composite properties can then be used in full field dual porosity simulations of fractured and vuggy reservoirs to correctly predict the oil recovery. The process described can be applied to any triple porosity reservoir where gas is invading the fracture-matrix system.
The Dangers of Volumetric and Financial Data Silos in E&P
Authors: Hull R. 
Published: December 2007

Abstract
Introduction
E&P companies struggle day to day with many challenges. With high oil prices, their primary focus is to effectively produce sufficient hydrocarbons to meet public requirements. With this in mind, data has become an area which has exploded. Now we see that the individuals are overwhelmed with the shear volume of data that is literally at their fingertips. During this time, the Sarbanes and Oxley act has resulted in the realization amongst E&P Company Management, that their popular solutions such as spreadsheets and home grown applications, contain errors which profoundly impact their financial bottom line. Many companies have found out "too late' just how bad these errors are.
In Cost/Schedule Integration
A Process for Project Management By: Ruthanne Schulte, she gives illustrations of how disparate systems can present a challenge.
"Two Products for Cost and Scheduling That Are Not Integrated
Many organizations use two or more products that are not integrated. When the cost and scheduling systems are not integrated, there are numerous drawbacks: They require dual data entry and therefore are cumbersome to maintain and have a high probability for error in the data entry phase.Non-integrated cost and scheduling systems can produce different results.Report verification is difficult due to the lack of an audit trail between the systems.Separate, non-integrated systems are often maintained by different people who report to different supervisors. Agendas may vary and communication gaps occur frequently. Significant discrepancies, and the results thereof, commonly occur in a non-integrated system.
There are positives and negatives for both spreadsheets (internal systems) and commercially developed systems. When a company is given a choice between the two, internal systems provide the benefit of being tailored to the company's specific requirements whilst a commercially developed system may not address these specific company needs. Also, an internal system can be edited and manipulated to continue to meet the ongoing needs of the organization. However, often staff does not have the experience or expertise to deal with these internal systems. A commercially developed system is often more user friendly. Companies need to weigh up these factors and decide the area in which they want to put their time and money towards; homegrown applications or commercially developed solutions.
Long-Interval, Open-Hole Gravel Packs
Authors: Gottschling John C. , Legan Thomas L. 
Published: December 2007

ABSTRACT
For control of formation sand production in California oil wells, the technique of open-hole viscous gravel packing is now being considered for long intervals of 1,500 feet to 2,000 feet. To effectively apply these high viscosity, high gravel concentration slurry packs, the designs and procedures used for the more common, short-interval treatments can he adopted if they are modified. A complete, step-by-step procedure for this technique and the pros and cons of various tools and methods are presented in this paper. Also, 13 case histories were chosen from among several hundred California slurry pack jobs for investigation. Case history data indicates that long-interval, slurry-pack completions are most successful when several considerations are taken into account. Among these considerations are (1) the effects of pack settling when choosing liner design; (2) the need of whether or not to use a seal bore and a lower, tell-tale screen; and (3) the percentage of calculated fill that should be in place prior to concluding gravel packing operations.
The Application of the Repeat Formation Tester to the Analysis of Naturally Fractured Reservoirs
Authors: Stewart George , Wittmann Manfred J. , van Golf-Racht Theodor 
Published: December 2007

ABSTRACT
The RFT* has important applications in the study of naturally fractured reservoirs in which low permeability matrix blocks are contained within a system of connected fractures of high permeability. The pressure inside an individual matrix block, which is observable with the RFT, is determined by the boundary pressure in the fractures delineating the block. Hence RFT data plotted on a pressure-depth diagram follow gradients corresponding to the fluids in the fracture system with changes in slope at the gas-oil and oil-water contacts. In an unproduced reservoir the actual OGOC and OOWC in the fracture system may be determined whereas logs measuring fluid saturations in the blocks indicate quite different distributions because of capillary pressure effects. RFT data from new wells in a developed reservoir allow monitoring of the movement of the GOC and OWC in the fracture network as a secondary gas cap forms and aquifer influx occurs.
Oil recovery from a fractured reservoir is controlled by the permeability of the fracture system and by the permeability and size of the blocks. Fracture permeability is readily available from the analysis of well pressure transient tests but the matrix properties are more difficult to determine. The test pressure response of the RFT, with the probe set in a block, is affected both by the matrix permeability and the block size and a simplified model of the process based on a spherical matrix block with a constant pressure outer boundary and a central point sink has been developed. It can be demonstrated that with a pressure gauge of 1 psi resolution matrix permeabilities of less than 5 md and block sizes of less than 2 m can be detected. The theory has been used to evaluate RFT tests in a fractured reservoir and good agreement between the estimate of block size using this technique and that obtained from a statistical analysis of core was found.
A finite-element numerical model has also been used to simulate pretest buildups in cubic and parallelepiped matrix blocks. The late-time deviation from linear spherical buildup commences when the nearest constant pressure boundary is encountered. Dimensionless buildup type curves for such matrix blocks are given.
The question of supercharging of the block pressure as a result of mud filtrate invasion has also been considered. The proximity of constant pressure fractures limits the degree of over-pressure which can develop at the sand-face. Supercharging only becomes a serious problem at very low matrix permeabilities and the RFT gives successful pressure measurements in fractured reservoirs with a tight matrix.
Pressure Buildup Analysis in a Naturally Fractured Shale Reservoir
Authors: Laudeman Scott K. , Ershaghi Iraj 
Published: December 2007

ABSTRACT
This paper presents case studies of pressure buildup analyses in certain oilfields in California producing from the Monterey formation. These miocene formations are thick siliceous and calcareous organic sediments. Production from the Monterey formation dates back to the turn of the century. In recent years additional exploration efforts have resulted in the discovery of new fields in the Monterey formation. Because of the impact that these fields will have on the proved reserves of hydrocarbon in California, improved evaluation techniques are required for these complex lithologies.
A review of conventional evaluation methods followed by a discussion and the importance of pressure transient tests are included here. Several case studies on onshore and offshore fields producing from the Monterey shale are presented.
Managing Produced Water through Total Oil Recovery: An Integrated Innovative Technology
Authors: Plebon M. J. , Saad Marc A. , Valikangas Antti 
Published: December 2007

Abstract
Produced water can become a major operational, environmental and economic concern when oil fields continue to mature. Managing and handling large quantities of produced water efficiently and effectively requires both understanding of the fundamental physical and mechanical characteristics of the water as well as the changes of those characteristics with both time and additional mechanisms.
TORR Canada Inc. (the company) have developed an innovative technology called TORR™ – Total Oil Remediation and Recovery (the technology) that integrates several oil and water separation and recovery principles is presented. The basis of operation of the technology to handle produced water oil separation and recovery characteristics is explained.
The critical produced water fluid characteristics such as oil droplet size distribution, dispersed oil stability and nature of the dispersed oil are presented and discussed. Performance is demonstrated through field data. Oil concentrations in the range of 100 to 300 mg/L have been reduced to well below 20 mg/L with the technology.
The performance of the technology represents a wide operational range of applications and associated economic and environmental benefits. Operators on offshore platforms who need to comply with stringent regulations may achieve the discharge targets with one technology and one stage. Additionally the technology deserves serious consideration to for the application of de-oiling produced water. Operational complexity of more traditional water treatment process trains can be greatly reduced.
Evaluation of Low Permeability Gas Reservoirs Utilizing Closed Chamber Drillstem Test Techniques
Authors: Reid Hugh W. 
Published: December 2007

ABSTRACT
Closed chamber drillstem testing was originally developed in the early seventies for reasons of operational safety to test geo-pressured, hydrate-prone, high-deliverability gas zones in the Canadian arctic. This original use of the method has been described by Alexander1,2. Since that time, the method has become adopted for more general use in the Western Canadian plains. The two major reasons for utilizing the method have been to preserve secrecy while testing wildcat wells adjacent to land available for sale and, more recently, to gain precision in testing low-permeability low-pressure gas sands.
This paper discusses the evaluation of such low permeability gas zones. The use of graphs of surface pressure versus time (cartesian and log/log co-ordinates) form an integral part of the interpretation process. Certain easily recognizable, well-defined, and abrupt slope changes in surface pressure buildup occur early in the preflow and flow periods. These may be used to qualitatively differentiate between low rate gas and liquid entry. The causes of these phenomena are explained and field examples are provided for illustration. The gas rates are verified independently by simple manipulation of the Equation for Corresponding States. Field examples with extremely low flow rates verified in this manner are presented. The overall configuration of the surface pressure buildup in the cartesian plots may also be utilized to distinguish between truly impermeable zones and those which have suffered severe damage and exhibit "cleanup" (changing skin factor). This may be accomplished even where the rates would be too small to measure in a conventional DST and where the entire surface pressure change throughout the flow period may be no more than 2 or 3 psi. Consequently, zones may be selected which will respond more favourably to stimulation even though calculation of skin damage using conventional Horner analysis or type curve matching may not be possible owing to insufficient shutin time.
A further application is the estimation of down-hole shutin time necessary to reach stable shutin pressure (utilizing the rates of surface pressure change during flow).
Data Acquisition in Pumping Wells
Authors: Cimic Miljenko , Soares Laura 
Published: December 2007

Abstract
Calculating of bottomhole flowing and shut-in pressures and bottomhole flowing rates, based on fluid level measurements and casing head pressures was combined with a convolution method of the build-up interpretation, for vertical and horizontal wells. The downhole pressures and rates were calculated using a mechanistic model(7), which shows good accuracy after comparing with downhole gauges measured data. The main uncertainty still remains the accuracy of fluid level measurement and water content in the annulus fluid, especially during well clean up period, which influences the density of the casing fluid column.
During the shut-in period, conventional pressure build-up analysis (Horner and derivative) and convolution methods were compared with the purpose of showing the advantages of the convolution method over the conventional. Consequently, the well test can be more rigorously interpreted by using convolution rate analysis, and the shut-in time is reduced by three folds, leading to economic advantage of testing costs saving.
The real time knowledge of bottomhole pressure and rates can be used to adjust the optimum downhole pump working regime, avoiding two phase flow through downhole pump and to perform conventional and convolution methods of interpretation without deploying bottomhole gauges. Majority of "brown fields" are equipped with different kind of artificial lift system including positive and dynamic displacement pumps. A fluid level measurement combined with a convolution method leads to an improvement of the production and operating economics of different types of artificial lift systems (SR, ESP, PCP, etc.) and can be used, as well, as a reservoir management tool. This paper includes actual field examples, with solutions that can be applied in the completion and testing of pumping wells. A field experience and subsequent achievement with downhole pumps testing in low permeability oil reservoirs are presented in this paper.
A Comprehensive Reservoir Model of the Low Permeability Lewis Sands in the Hay Reservoir Area, Sweetwater County, Wyoming
Authors: Brown Charles A. , Erbe Charles B. , Crafton James W. 
Published: December 2007

ABSTRACT
Natural gas is currently being developed and produced in the Hay Reservoir Area from deep, high pressure, low permeability reservoirs. The reservoirs are predominantly offshore sand deposits which have been significantly altered since deposition. As a result, the reservoirs are difficult to interpret from logs, require stimulation to provide commercial flow rates, and necessitate more sophisticated evaluation methods than conventional reservoirs.
Traditional reservoir engineering approaches are discussed and found to be inadequate in the evaluation of these low permeability sandstone reservoirs based on early life performance. A method of reservoir study is developed by integrating methods from several technical disciplines including geologic reservoir modeling, petrography/reservoir quality analyses, log interpretation modeling, and ultimately, reservoir simulation to rigorously evaluate individual well deliverabilities and reserves. Results show that significantly more gas is economically recoverable than traditional methods of analysis would indicate.