bluuebunny/crossref_metadata_2025_split huggingface dataset:
Pressure Transient Analysis of a Shallow Horizontal Gas Well: Test Objectives, Design, Procedure, Interpretation, and Application of Results
Authors: Cochrane J. F. , Reynolds K. C. 
Published: December 2007

Summary
In 1990 Texaco Exploration and Production Inc. drilled and completed the first horizontal wells ever drilled in the Gulf of Mexico. The wells, East Cameron Block 278 "B" Platform Wells B-12 and B-14, are about 195 nautical miles southwest of New Orleans, Louisiana in 173 feet of water. The wells are completed in a shallow gas sand at a depth of about 1700 feet TVDSS.
The B-14 well was tested in April 1991. The primary objective of the test was to obtain data for a reservoir simulation study to compare the ultimate recovery of a horizontal and a vertical well in the same reservoir. Other objectives were to use the simulation model to optimize production rates; to characterize inflow performance; to evaluate the slotted liner/prepack gravel pack completion; and to use the data to optimize the length of the horizontal section in future wells. To meet the test objectives, five high resolution quartz memory pressure gauges were placed throughout 380 feet of the horizontal section.
Based on the analysis of the test data the following conclusions were reached: the horizontal well will recover nearly twice as much gas as a conventional well completed in the same reservoir; the optimum rate for each well is about 20 MMSCFD; the reservoir is contributing flow along the entire length of the horizontal section; and that gas flowed outside the prepack gravel pack completion during the test. Test data also indicate that the common assumptions of infinite conductivity and uniform flux are not valid for this well.
This paper describes the test objectives, design, operational aspects, alternatives evaluated, test data, interpretation and application of results, and the ultimate recovery of a horizontal well versus a conventional well.
Crawford: The First U.K. Field Abandonment
Authors: Dall R. N. , Gilliver R. E. , Sclater Raymond 
Published: December 2007

Abstract
In 1991 Crawford became the first UK North Sea field to be abandoned. Novel approaches were employed both in the design of the development and in the methods used to abandon the wells and facilities. These, together with detailed planning and early involvement with the UK authorities, contributed to the success of the abandonment operations which were completed under budget and without injury. Most of the equipment recovered was in suitable condition for re-use.
Well abandonment and subsea facilities removal operations were conducted concurrently. The Yatzy, a dynamically positioned (DP) semi submersible drilling rig, was used to abandon the wells. The use of a dynamically positioned rig resulted in flexibility in the sequencing of operations and time and cost savings on rig moves. It was able to work very closely with the dive support vessel (DSV) Stena Constructor used to recover the subsea facilities and to assist with re-entering the subsea wells.
Continued Development, Reservoir Management and Reservoir Modelling Have Increased Proven Developed Oil Reserves by Over 35% in the Marginal Scapa Field
Authors: Ellison R. L. , Simlote V. N. , Ko R. S. 
Published: December 2007

Summary
The understanding of reservoir performance, reservoir heterogeneity, distribution of oil in place and continued data gathering has resulted in a reservoir description and predictive model for use in evaluation of reservoir response to waterflood processes and recovery efficiency for this marginal offshore field.
The vital data for assessing the reservoir flow characteristics were obtained from annual production log surveys, requiring a floating rig at the template and continuous pressure recordings obtained from the permanent downhole gauges in template and platform producers.
An active data gathering program during a prolonged shut down period provided valuable information for the field history match.
Original oil in place (OOIP) in the Scapa field is estimated as 248 million STB. The field had produced about 40 million STB or sixteen percent OOIP through 1991.
The ongoing field development drilling has further provided the extent of the oil accumulation and improved understanding of the geology. This paper assesses the value of the routine reservoir management data acquisition programs which results in improved understanding of reservoir production behaviour resulting in increased proven developed oil reserves by thirty-five percent in this marginal offshore field.
Remediation of the Contaminated Ocean Floor Around Offshore Platforms in the Gulf of Mexico
Authors: Fang C. S. , Tao Kaiqin , Lin Jong-Her 
Published: December 2007

ABSTRACT
The previous effort of cleaning the contaminated ocean floor around offshore platforms in the Gulf of Mexico has been evaluated and an improved cleaning process is presented based on the preliminary study which uses laboratory experimental data, field data and computer calculations. The improved cleaning process includes filtration, air flotation and carbon adsorption operations. The improved process can reduce the organic compounds returning to the ocean from 841 ppm to approximately 5 ppm.
The Effect of pH on the Adsorption and Transport of Phosphonate Scale Inhibitor Through Porous Media
Authors: Sorbie K. S. , Yuan Ming Dong , Chen Ping , Todd A. C. , Wat R. M. S. 
Published: December 2007

AbstractThis paper presents results and analysis for several cycles of low concentration phosphonate (DETPMP) inhibitor floods in highly reproducible sandpacks. The central objective of this work is to present a detailed study of the effects of solution pH on the adsorption behaviour of phosphonate inhibitor. Displacements at constant near neutral and low pH conditions and in pH gradients have been carried out The latter type of flood is analysed in terms of coupled adsorption where the adsorption isotherm is a function of both inhibitor concentration and [H+] (or pH). The main finding is that phosphonate inhibitor adsorption level is higher at lower pH values. Non-equilibrium adsorption is also evident in the low pH floods. The floods are simulated and analysed using a non-equilibrium, coupled adsorption numerical model which reproduced most of the main features observed in the experiments. The modelling also leads to some novel interpretations of the experimental results which are then tested by further experiments. In order to put this study in a practical context, some further sensitivities, to calcium ion concentartion and pH on high concentration phosphonate adsorption, are also presented in this work. Again, it is shown that the pH and [Ca++] effects exert a coupled influence on phosphonate adsorption.
Ion Chromatography Tracer Experiments During Drilling
Authors: Hall Christopher , Hughes T. L. 
Published: December 2007

Abstract
We describe field tests carried out to show that salt tracers injected into the mud at the surface during drilling can be used to measure the extent of hydrodynamic dispersion during well-bore circulation. The results of one test using lithium bromide are described in detail, together with the procedures for tracer injection, sampling of return mud, and chemical analysis by ion chromatography. Test data are analysed in terms of residence time theory, and the residence time density function, cumulative distribution function and washout function are computed. Results suggest that circulation is well-mixed and is close to plug flow. The observed washout function is compared with the predictions of several simple models. The anion was completely recovered in the filtrate but cation losses were observed which are attributed to ion exchange with clay solids during circulation. In tests with salt mixtures, cation losses reflect the affinity of ions for clay cation exchange sites.
Physical/Chemical Studies on the Surface Interactions of Bentonite With Polymeric Dispersing Agents
Authors: Rabaioli M. R. , Miano Fausto , Lockhart T. P. , Burrafato Giovanni 
Published: December 2007

ABSTRACT
This paper describes an experimental investigation of the effect of various commercial anionic polyelectrolyte thinners on the stability of bentonite dispersions contaminated by mono and divalent salts. Combined adsorption and electrophoresis studies lead to the definition of a model for the mechanism of interaction between the polyelectrolyte and clay. The data presented suggest that, with the exception of FeCr-lignosulphonate, the thinners adsorb preferentially onto the edges of the clay particles. In the case of FeCr-lignosulphonate significant adsorption onto the faces of the bentonite is attributed to the bridging effect of the polyvalent metal ions. The different adsorption mechanisms have consequences for the amount of polyelectrolyte required to deflocculate and stabilise the dispersions. Flocculation tests confirm that polymers adsorbing selectively on the "edge" sites are more effective in stabilising the dispersion against flocculation than those which adsorb less selectively onto the bentonite surface. Interestingly, the rheological properties of bentonite dispersions improve even where the thinner produces a scarce deflocculation effect At least two mechanisms appear to describe the rheology-reducing properties of the thinners studied. Thinners like FeCr-lignosulphonate, which do not deflocculate the dispersions, can be distinguished from others such as the polyacrylates, which are true dispersing agents for bentonite in the presence of high electrolyte concentration, by means of scaling analysis of the rheological results.
Surfactants: Additives to Improve the Performance Properties of Cements
Authors: Cowan K. M. , Eoff Larry 
Published: December 2007

ABSTRACT*
The primary focus of this paper is on the use of surface active agents (surfactants) to modify the properties of Portland cements for well cementing operations. Surfactants, as abroad class of compounds, have been largely ignored as additives to improve the performance of cements for well applications. Use of surface active agents in cements is primarily within two main functions – retarding agents and dispersing agents. The surface active agents currently used for these two functions do not provide the benefits that other types of surfactants can provide.
The types of surfactants discussed here are distinctly different in functional groups, physical characteristics (molecular weights), solution properties and effect on cement properties than presently used surface active agents. The potential widespread benefit from the use of these materials in cement formulations can be seen. Some of the benefits which can be realized by incorporating the types of surfactants studied in this work are: (1) improved interfacial sealing between cement and pipe, (2) less shrinkage of the cement during setting and hardening, (3) savings on cement materials and (4) improved cement properties at lower cost.
Asphaltene Precipitation: A Need for a Broader View
Authors: Deo M. D. , Hanson F. V. 
Published: December 2007

Abstract
Asphaltene content of an ultra-heavy oil was compared to the asphaltene contents of residual fractions obtained after supercritical extraction of the oil with propane. The asphaltene contents of the residual fractions were found to be significantly greater than the asphaltene content of the original oil even after prorating the values to weight percent of the original oil. This increase was believed to be due to the depletion of lighter cosolubilizing compounds from the oil. The H/C atomic ratio of the residual fractions was lower compared to the original oil, indicating that the ratio of polar to nonpolar compounds may also be important from precipitation considerations. Saturate and aromatic compounds were preferentially extracted and the ratio of asphaltenes to resins increased in the residual fractions relative to the original oil. The data demonstrated that the asphaltenes in the original oil were not the only compounds susceptible to precipitation and that a broader view of the precipitable material is necessary in order to understand the precipitation problem in oil reservoirs.
Field-Related Mathematical Model to Predict and Reduce Reservoir Souring
Authors: Sunde Egil , Thorstenson Tore , Torsvik Terje , Vaag J. E. , Espedal M. S. 
Published: December 2007

ABSTRACT
A mathematical model for reservoir souring caused by growth of sulfate reducing bacteria (SRB) in the reservoir has been developed. The model is a 1D numerical transport model based on conservation equations and includes bacterial growth rates, the effect of nutrients, water mixing, transport and adsorption of H2S in the reservoir formation.
Two basic concepts for microbial H2S production were tested using the model: H2S production in the mixing zone between formation water and injection water (mixing zone model), and H2S production due to SRB growth in a biofilm in the reservoir rock close to the injection well (biofilm model). In both cases H2S adsorption by reservoir rock was considered.
Field data obtained from three oil producing wells on the Gullfaks field correlated with H2S production profiles obtained using the biofilm model, but could not be explained by the mixing model.
The biofilm model implies that H2S production is correlated to the quality of the injection water, especially nitrogen (N) and phosphorous (P). The use of chemicals (containing N and P) in injection water treatment should therefore be reduced to a minimum.
A Reservoir Simulation Study of a Cooperative Waterflood
Authors: Herbert William F. , Wattenbarger Robert A. 
Published: December 2007

Abstract
A small pressure maintenance project was surrounded by a larger project with higher producing allowables. Cooperative water producing allowables. Cooperative water injection wells had been selected along the leaseline to provide for the displacement of equal areas across the lease boundary. A cooperative agreement had been made which governed the injection and producing rates of both parties in the vicinity of the leaseline.
A reservoir simulation was undertaken to determine if the cooperative agreement and operating policies could be changed to the additional benefit of both leases. The waterflood was modeled with a two-dimensional three-phase unsteady-state reservoir simulator. A number of possible operating conditions were simulated to determine their effect on leaseline oil migration, and oil and water production. From the series of runs, an understanding of the mechanics of the waterflood was developed which would not have been possible without the quantitative results of reservoir simulation. The fillup, productivity, and three-phase flow effects productivity, and three-phase flow effects were all very important. Recommendations were made which should make the project more profitable to both leases. profitable to both leases. Three cases are presented to illustrate the application of reservoir simulation to the problem. The comparison of cases shows that problem. The comparison of cases shows that it is possible to select leaseline injection and production rates which will further reduce oil migration and still result in better oil and water producing characteristics for both leases.
Introduction
This paper discusses a reservoir simulation study of the problem of leaseline migration in a cooperative waterflood. The usual approach is for the operators to enter into an agreement which sets limits on water injection rates and pressures. To reduce oil migration, they agree to produce leaseline wells at low rates, below their producing capacities. The cooperative agreements usually apply to all leaseline wells regardless of their locations or producing characteristics.
In this particular waterflood, an agreement of this type had been in effect for the first 18 months of the waterflood. The primary purpose of the simulation study was primary purpose of the simulation study was to see if the cooperative agreement could be altered to the additional benefit of both leases.
Effective History Matching: The Application of Advanced Software Techniques to the History-Matching Process
Authors: Parish R. G. , Calderbank V. J. , Watkins A. J. , Muggeridge A. H. , Goode A. T. , Robinson P. R. 
Published: December 2007

Abstract
The modelling and history matching of hydrocarbon reservoirs is widely accepted to be a challenging task requiring considerable expertise.
This paper describes the application of advanced statistical and knowledge based techniques to the development of a software tool aimed at making the history matching process more efficient and effective. We conclude that, provided such systems are used as decision support tools for the reservoir engineer, they can significantly enhance the ability of the human expert to obtain a satisfactory history match.
Reservoir Characterization of a Fractured Reservoir Using Automatic History Matching
Authors: Smith R. A. W. , Tan T. B. 
Published: December 2007

Abstract
The Subject oil reservoir will not be identified to preserve requests of confidentiality. Oil production from the Subject field is primarily from a highly fractured and faulted formation. The initial reservoir pressure is several thousand psi above the bubble point pressure. Pressure surveys after one year of production mdicated a recharge source. The source of the pressure support could be from (a) the matrix volume assuming a dual porosity system, (b) an aqwfer composite system or (c) an oil filled composite system with a low permeability outer zone. Matching the pressure data with any of these reservoir descriptions would establish the most plausible reservoir characterization. However, to carry out the task of varying the parameters of each reservoir description until a satisfactory match is obtained for that particular description would be extremely onerous and time consuming if done manually.
To solve this problem, a three-dimensional three-phase reservoir simulator with automatic history matching capability was used. The simulator was able to obtain the best possible match for each reservoir description by regressmg on the porosity and directional permeability parameters. The competing models were then compared and the model that matched the historical pressure observations as well as conforming to the established parameters of the geological model was determined to be the true model.
The results of the above analysis indicated that the dual porosity system did not provide an acceptable fit of the pressure data and thus it was rejected. Excellent matches were obtained with the aquifer composite model and the oil filled composite model. The parameters of the aquifer composite model that were necessary to obtain a match did not conform with other geological and pressure transient analysis mformatlon. However the oil filled composite model parameters were in close agreement with the well test interpretation model and the geological features of the reservoir. This was the model that was fmally accepted. Thus automatic history matching was a valuable tool in the reservoir characterization of the Subject Reservoir.
The Modeling of Flow in Heterogeneous Reservoirs with Voronoi Grid
Authors: Palagi C. L. , Ballin P. R. , Aziz Khalid 
Published: December 2007

Abstract
The flow rate at each interface between gridblocks is a function of an "effective" permeability of the connection. The upscaling procedure consists of evaluating average connection permeabilities based on a smaller scale description of the reservoir. While several procedures have been reported in the literature to scale up permeability values for Cartesian grids, these procedures have not been extended to flexible grids. The Voronoi grid allows the specification of each gridpoint independently; therefore, it provides flexibility to represent wells and reservoir heterogeneities.
This paper describes an upscaling procedure of permeability values at the interface of Voronoi gridblocks. The description of the heterogeneity, e.g., a stochastic image, is independent of the grid geometry. The power law average of the permeability values at each connection is computed automatically by the computer code. The optimum value of the power law coefficient is determined by comparing fine and coarse grid results for selected images and well configurations.
Several well configurations were investigated with different grid geometries (Cartesian, hexagonal and locally refined hexagonal) using the same description of the reservoir. The optimum value of the power law coefficient was almost the same for all combinations of grid geometries and well configurations (between -0.5 and 0). Also several stochastically generated images of the reservoir, all honoring the same data, were analyzed. Again the optimum value of the power law coefficient was almost the same for all images. The hexagonal grid yields more robust results because each gridblock has more neighbors than the Cartesian grid. The use of local grid refinement around wells reduces the overall error.
Eighth SPE Comparative Solution Project: Gridding Techniques in Reservoir Simulation
Authors: Quandalle Philippe 
Published: December 2007

AbstractThis paper reports the results of a Comparative Solution Project (CSP) which compares different flexible gridding techniques now available in some reservoir simulators. This CSP was performed by five participants and the problem posed is a 3D simulation of oil production associated with gas injection in a four layer reservoir. The participants were asked to provide two sets of results with the same simulator : the first set corresponding to a simulation run with a regular 10x10x4 Cartesian grid, and a second set corresponding to a simulation run with a flexible grid optimised to have as few grid nodes as possible.Two different types of flexible grid have been used by the participants, Control Volume grids (CVG) [1,2], and Locally Refined Cartesian grids (LRCG) [3,4], These grids are shown in the paper.With flexible grids, all participants could reduce the number of grid nodes by a factor four or more, while keeping the simulation results close to those obtained with the regular 10x10x4 Cartesian grid.
Economics of Coalbed Methane Field Development: A Case Study of Jatibarang Field
Authors: Nugroho Wisnu 
Published: December 2007

Abstract
Coalbed methane is a new energy resource that has not been developed in Indonesia. The reserve is estimated about 213 Tcf and spread over 16 basins. The utilization of this new energy resource will undoubtly contribute the industrial development in the country. This paper focuses on the technical and economic aspects of coalbed production in Jatibarang field, West Java. The methane reserve in this West Java area is 21 Tcf, and the location is quite strategic due to its proximity to the highly viable market of growing industrial nearby area. This paper presents a proposal of CBM development in Jatibarang field. The result shows a very lucrative return for the investment on the project based on production sharing agreement.