bluuebunny/crossref_metadata_2025_split huggingface dataset:
An Evaluation of Gas Field Rules In Light of Current Conditions and Production Practices In the Panhandle Non-Associated Gas Fields
Authors: Brady C. L. , O’Rear C. H. 
Published: December 2007

Abstract
During the early years of development in the Panhandle fields the Rule of Capture was king. Under the Rule of Capture each property owner has the right to drill as many wells as desired at any location. Adjacent property owners protect their rights by doing the same. Courts adopted the Rule of Capture to protect mineral owners from liability due to migration of oil and gas across property boundary lines. This general practice "to go and do likewise" generally leads to enormous economic and natural resource waste.
Established to offset the waste created under the Rule of Capture is the doctrine of Correlative Rights. Correlative Rights is the right of each mineral owner to obtain oil and gas from a common source of supply under lawful operations conducted from his property. However, each mineral owner has a duty to every other mineral owner not to extract oil and gas in a manner injurious to the common source of supply.
This paper will examine the historical context of these common law principles with regard to the Panhandle non-associated gas fields. Discovered in 1917, the Panhandle fields are ideal to evaluate the merit of statutes and regulations enacted in response to production practices. As in many Texas fields, proration in the Panhandle fields is the primary mechanism to protect correlative rights and prevent waste. Signed and made effective May 1989, the current field rules pre-date much of the enhanced recovery techniques that use well-head vacuum compression. This paper reviews the gas rules in the 1989 Texas Railroad
Commission order in light of current reservoir conditions and production practices.
Potential Distribution Around Sources With Finite Length Horizontal, Vertical Partially Penetrating Wells and Fractures Part II: Transient Flow
Authors: Azar-Nejad F. , Tortike W. S. , Farouq Ali S. M. 
Published: December 2007

Abstract
The potential distribution around a partially penetrating source is a solution of the diffusivity equation. Presenting a new method "Discrete Flux Element" (DFE) this paper provides the solution to the diffusivity equation with uniform potential as well as uniform flux inner boundary conditions (IBC). This solution provides the ability for modeling any sources with arbitrary geometry. The pressure derivative equations have been derived for uniform potential as well as uniform flux inner boundary conditions. The pressure derivative reflects the wellbore length and the distance of a horizontal well to the no-flow boundary.
Conversion of a Semisubmersible Drilling Rig to a DP Unit
Authors: Vale Edson L. Megale , de Medeiros Edmilson S. , Neto Arthur C. , Ferreira Paulo P. Ribas 
Published: December 2007

Abstract
The scopc of work which this paper is based on is the conversion of the semisubmersible drilling rig PETROBRAS-XXIII (Ex-VINNI) from the original mode of operation to a dynamic positioning unit, capable to operate on offshore fields of Brazilian coast from 100 to 1500 m water depths.
Originally such unit was designed by GVA, named GVA 4000, to operate up to 460 m water depth, positioned by means of a 8-point mooring system.
The conversion is based on the brazilian waters environmental conditions and the design criteria is according to DNV rules and the principle of NMD, as stated for class 2.
Controlling Water Production In Naturally Fractured Reservoirs With Inorganic Gel
Authors: Fragachán F. E. , Cázares-Robles F. , Gutiérrez J. J. , Herrera G. 
Published: December 2007

Abstract
This paper presents the results of successful applications of inorganic gels to control water production. In naturally fractured reservoirs a case study with hostile high temperatures (260-310 °F) found in the Cretaceous and Jurassic dolomitic limestone's of the south east of Mexico is presented together with a water exclusion case from the tertiary sandstones. Importance of gel penetration and selective placement to considerably delay the water percolation to upper intervals in hydraulically communicated intervals is discussed. Included are alternatives for control of gel invasion from the high conductivity fracture network to the tight matrix. Finally, the paper presents a brief discussion of the future of water control in naturally fractured reservoirs.
Design and Analysis of Fractured Horizontal Wells in Gas Reservoirs
Authors: Soliman M. Y. , Azari M. , Hunt J. L. , Chen C. C. 
Published: December 2007

Abstract
Although horizontal wells may offer significant production improvement over vertical wells, it may be necessary to fracture horizontal wells to maximize their return on investment. This is especially true in the case of tight gas formations.
This paper presents a model for fractured horizontal wells operating under constant pressure conditions, which is most suitable for producing tight gas reservoirs. The created fracture may be longitudinal or transverse. In this paper we examine the factors involved in determining the optimum number of transverse fractures for both finite and infinite reservoirs. For a group of transverse fractures, the rate distribution for each fracture is presented and analyzed. The effect of uneven fracture length is briefly presented.
The performance of a longitudinal fracture is examined and compared to a fractured vertical well and to a transverse-fractured horizontal well. A comparison of longitudinal versus transverse fractures from reservoir and operational points-of-view is presented. Also included is a short discussion of field examples.
Because performance of a longitudinal fracture is almost identical to that of a fractured vertical well, the existing solutions for fractured vertical wells may be applied to longitudinal fractures with a high degree of confidence. This approximation is valid for moderate to high dimensionless conductivity. In the case of transverse fractures, the outerfractures outperform the inner fractures. However, more than two fractures are necessary to efficiently produce the reservoir for most cases. A simplified economical analysis supports this conclusion.
Applications of Simulated Annealing on Actual but Atypical Permeability Data
Authors: Savioli G. B. , Falcigno E. D. , Bidner M. S. , Lake L. W. 
Published: December 2007

Abstract
The use of geostatistics is becoming recognized as a standard means of representing reservoir heterogeneity, Geostatistics has enjoyed an extensive use and a fairly well developed theoretical base. This is a little less true of simulated annealing (SA), the form of geostatistics tested here, but it is also a mature technology.
Yet there remains a need to exercise these procedures under actual conditions of nonuniformly sampled data, non-Gaussian distributions and truncated data sets. Providing insights into how to deal with these nonidealities is the objective of this work,
We find that SA estimates are improved when the original data sets are power-transformed. However, SA estimates tend to deviate from the input cumulative distribution function (CDF) because of excessive rejections. This deviation can be corrected by including the CDF into the SA objective function.
Biological Water Profile Control - Designing a Concept for North Sea Application
Authors: Paulsen John E. , Sørheim Roald 
Published: December 2007

Abstract
Water profile control, using indigenous nitrate reducing seawater bacteria in North Sea waters as blocking agents, has been investigated. Feasibility studies have been carried out, both in a micro (micromodels) and a meso scale (sand packs), aiming at identifying parameters that are critical for the process. The results show that there are several factors that are important for the penetration and distribution of a bioplug in a porous matrix. Although lab experiments have shown that bacteria preferentially block high permeable zones, it is questioned how relevant this information is for practical purposes. The long distances involved in transport of bacteria and nutrients into North Sea reservoirs implies problems that have to be resolved. Biofilms growing as a network in pores in the matrix, biowebs, are proposed to play a major role in the development of a bioplug. The filterability of the matrix is increased once the bioweb is established, and entrainment of fines and bacteria is dramatically impeded. pH alterations, due to acidic metabolic by-products, is believed to be rate limiting for the generation of biomass in the porous matrix. This problem, in conjunction with the problem created by the biowebs, is speculated to be main obstacles in a plugging scheme in large fields with distant target zones. The problem of scale seem to be extremely important. It is questioned if the current methodological approach in the study of biofilms is adequate for studying phenomena that aredistant in,time, and space.
Gel Systems for Controlling CO2 Mobility in Carbon Dioxide Miscible Flooding
Authors: Raje M. , Asghari K. , Vossoughi S. , Green D. W. , Willhite G. P. 
Published: December 2007

Abstract
Carbon dioxide miscible flooding is widely used in carbonate reservoirs in West Texas and has potential application to carbonate reservoirs in other areas of the country including Oklahoma, central, and southwest Kansas. One of the major difficulties of this process is the CO2 early breakthrough because of its unfavorable mobility ratio and because of the heterogeneous nature of this type of reservoir. Injection of alternating slugs of water and carbon dioxide, known as the WAG process, is the remedy most widely applied to control the early breakthrough, but its success has not been universal. Conformance control using gels has not been widely attempted. Laboratory research efforts at the University of Kansas have produced promising in situ gelation techniques aimed at this application.
Three in situ gel systems have been developed and tested in laboratory cores to control the movement of supercritical CO2 in matrix rock. Two systems are based on a new biopolymer, termed KUSP1, which is soluble in alkaline solutions above pH 10.8, but forms firm gels when the pH is reduced to 10.8 or below. The third gel system uses the reaction of sulfomethylated resorcinol and formaldehyde to form a gel. This paper describes the behavior of these gel systems at 32.2-41°C in Berea sandstone cores (initial permeability ~ 70 – 700 md) when exposed to supercritical carbon dioxide and brine after in situ gelation.
KUSP1 gel systems were studied using two different methods of inducing in situ gelation. In the first method, gelation was accomplished by injecting CO2 at low pressure into the Berea sandstone core saturated by alkaline polymer solution. Permeability reduction to the brine and CO2 in the range of 80% was achieved. Stability of the gel was tested in the presence of supercritical CO2. When supercritical CO2 was used to induce in situ gelation, the same degree of permeability reduction was achieved. The gel remained stable after the injection of many pore volumes of supercritical CO2. The second method of initiating in situ gelation involved the use of an ester. Hydrolysis of the ester, monoethylphthalate, in the alkaline polymer solution caused the pH to drop to levels where in situ gelation occurred. The permeability of the treated core to supercritical carbon dioxide was about 1 md which was equivalent to a permeability reduction of 95-97 % of the initial brine permeability.
The third gel system, based on the reaction of sulfomethylated resorcinol and formaldehyde, termed SMRF, was gelled in situ and contacted with both brine and supercritical CO2. Permeabilities to carbon dioxide on the order of 1 md or less were observed. This permeability is equivalent to a reduction of about 99% in the initial brine permeability. Reduced permeabilities were maintained after injecting many pore volumes of supercritical CO2 and brine.
Optimization of Miscible Water-Alternate-CO2 Injection (Based on analytical model)
Authors: Bedrikovetsky P. , Andrade G. M. , Ferreira L. E. A. , Menezes G. L. 
Published: December 2007

Abstract
A new analytical model for the miscible CO2-WAG is developed. The model is based on analytical solutions of non-self-similar and self-similar problems for system of hyperbolic equations of mass conservation laws. Explicit formulae allow to analyse propagation of displacement and phase transition fronts, mechanisms of trapping of oil with the sequential injection of water and gas slugs, mobility ratios on shock fronts and the dynamics of water and gas slugs.
Five different regimes for gas-water injection have been distinguished depending on the water-gas ratio. They differ from each other by different structure of the mixture zone and displacement mechanisms caused by phenomena of two-phase displacement and phase transitions.
The analytical model presented shows that the higher the WGR the lower the recovery, but the more favourable is the mobility ratio on the displacement front. These suggest the existence of an optimal water-gas ratio (WGR).
As it follows from the analytical model there does exist a minimum slug size which prevents gas breakthrough via all the water slugs. With the injection of thinner slugs a connected gas network appears in the reservoir which will catch up the front of water and will create an unstable gas-oil front at the presence of the connate water only. So, simultaneous injection of gas and water, which accords to the reduction of slug size to the zero limit, is not an optimal WAG regime, as it was suggested in the literature. On the other hand the thinner the slugs the higher the displacement efficiency. These speculations suggest the existence of an optimal slug size with the miscible WAG.
Permeability Damage in Diatomite Due to in-situ Silica Dissolution/Precipitation
Authors: Koh C. J. , Dagenais P. C. , Larson D. C. , Murer A. S. 
Published: December 2007

Abstract
It has been observed in Mobil’s California diatomite thermal recovery projects that water injectivity decreases gradually with time. Several factors, such as reservoir fill-up or high suspended solids concentration in the injection fluid, may effect such decrease. Due to the inherently low permeability of diatomite, small amounts of in-situ silica dissolution and/or precipitation can also have a drastic effect on the matrix permeability and consequently the injectivity. In this study, we outline an experimental program designed to ascertain such behavior and to elucidate qualitative and quantitative results to further our understanding of the problem. Furthermore, transient flow experiments were performed to obtain silica dissolution/precipitation data at various temperatures. It is shown that the silica reaction can be modeled approximately as first-order kinetics. Numerical model results indicate that this kinetic data can be used to model diatomite permeability damage data obtained in the laboratory. Our current effort to simulate field-scale permeability damage using the experimentally-derived silica kinetic model will also be discussed.
Improving CO2 Floods in Heterogeneous Media
Authors: Yaghoobi H. , Tsau J. S. , Heller J. P. 
Published: December 2007

Abstract
Selective mobility reduction (SMR)-enhanced foam reduces mobility of CO2 by a greater fraction in high than in low permeability cores in the laboratory experiments.1–4 The occurrence of such an exciting property has been verified several times experimentally with isolated core samples ranging from less than one to more than 900 millidarcies. However, the existence of SMR in composite, heterogeneous cores as well as the benefits of applying this unusual property in oil recovery have not been investigated. This paper addresses both the effect of foam on improving CO2 mobility in heterogeneous rocks, and also examines further the effect of heterogeneity on gas floods unprotected by surfactant.
To simulate experimentally the heterogeneous character of reservoir, composite cores which contain coaxial zones of high and low permeability in capillary contact are used in the latest experiments. The experiments are conducted in a high-pressure flow system that enables the flows to be segregated, with the brine and CO2 effluent from each of the zones collected and measured separately. The preliminary results indicate that the capillary contact between parallel zones does not diminish SMR. This interesting and striking finding clarifies the existence of SMR and its applicability in a real reservoir condition. As in previous single core tests, however, it is found that not all surfactants exhibit SMR to the same extent and that lower surfactant concentrations often provide a more intense SMR than do stronger solutions.
To model computationally both displacement and steady-state flow in a parallel-layered system with no foam, a DOE-distributed MASTER (Miscible Applied Simulation Techniques for Energy Recovery) reservoir simulator was used. The numerical results agreed qualitatively with those of the "control experiments" undertaken for comparison with the foam experiments performed in the same parallel system and reported earlier.5 These results were that the flow induced a saturation contrast between the parallel regions of different permeability. In the case of CO2 or other gas floods, this effect increases the high mobility ratio.
Reservoir Characterization by Integration of Seismic and Dynamic Data
Authors: Huang Xuri , Kelkar Mohan 
Published: December 2007

Abstract
This paper presents a systematic procedure for integrating 3D seismic data and production data to develop a detailed reservoir description. The procedure involves three steps. Step one includes the inversion of the seismic data to construct impedance distribution with the well core and log data. Step two includes the simulation of porosity values consistent with the impedance data. The last step involves the estimation of permeability values consistent with its relationship with porosity as well as the dynamic information. All these three steps are discussed in detail. The procedure is further validated by applying it to both synthetic and the field data. The results obtained have been satisfactory illustrating the suitability of the method.
Crossflow in Fractured/Layered Media Incorporating Gravity, Viscous, and Phase Behavior Effects: Part II - Features in Fractured Media
Authors: Dindoruk B. , Firoozabadi A. 
Published: December 2007

Summary
Crossflow across the interfaces of layered reservoirs, and between matrix blocks and fractures in fractured reservoirs may be very pronounced.
In Part I of this study, the results of our work on crossflow in layered media were discussed. In this paper, the results for fractured porous media will be presented. Based on several example problems, we observe a significant contribution of crossflow to recovery performance in a fractured porous medium. In one example, the in-place hydrocarbon recoveries at 1 PV injection are 68 percent with crossflow between the matrix and fracture, and 47 percent without crossflow. Those results correspond to a single matrix block. The effect of crossflow in a multiblock system may be even more pronounced.
The results presented in this paper provide a real challenge for compositional simulation of fractured reservoirs.
Application of Seismic Data and Sequence Stratigraphy for Constraining a Stochastic Model of Calcite Cementation
Authors: Bakke N.E. , Ertresvag E.T. , Naess A. , MacDonald A.C. , Falt L.M. 
Published: December 2007

Abstract
Calcite cemented sandstone layers are common heterogeneities in shallow marine reservoirs where they cause significant flow barriers. Field analogue studies indicate that the most laterally persistent cemented layers are associated with sequence stratigraphic bounding surfaces where the cementation forms a complex network of beds concentrated around both maximum flooding surfaces and sequence boundaries.
Although individual calcite cemented beds are thin, they are associated with very high acoustic impedances and concentration of these thin, high impedance beds around bounding surfaces produces a significant seismic response which can be used to provide information on the spatial distribution of flow barriers. This information along with a sequence stratigraphic interpretation of the reservoir and geometrical data extracted from field analogues provides the input for an integrated reservoir description of calcite cemented barriers using a stochastic modelling approach.
The stochastic model is a non-stationary indicator field with an external trend in the indicator proportions. Variograms are used to control the geometry of individual cemented beds. Sequence stratigraphy and seismic data are used to define spatial trends in the proportion of cemented beds; sequence stratigraphy provides the vertical constraints, and seismic data provide lateral constraints.
The modelling approach has been tested using data from the TOGI area of the Troll gas field in the Norwegian North Sea. A controlled (verifiable) test has been carried out using synthetic seismic data based on a realistic, heterogeneous, 3D acoustic model of TOGI. These data have been inverted using a constrained sparse-spike seismic inversion technique. The test demonstrated that the prototype modelling procedure functioned satisfactorily. The integration of data from several sources contributed to the generation of realistic heterogeneity models constrained by a maximum amount of information.
A test using real seismic data from TOGI has been initiated. The results of the sparse-spike inversion are similar to those obtained in the synthetic test. These inverted data are presently being depth converted and prepared for use in stochastic heterogeneity modelling.
Upscaling Of Permeability: Implementation Of A Conditional Approach To Improve The Performance In Flow Simulation
Authors: Almeida J.A. , Soares A. , Pereira M.J. , Daltaban T.S. 
Published: December 2007

Abstract
In the present work it is proposed a conditional and iterative approach of upscaling of permeability based on the formulation of mass balance equations and Darcy's Law. In the classic approaches, the effective permeability in a particular set of blocks derives from the application of a pressure gradient between two opposite boundaries and imposing a no flow condition in the others. Based on the solver pressure techniques, the idea is to improve the quality of upscaling by including, in the calculation of the equivalent permeability of each large scale block (macroblock) the influence of the permeability values in the set of neighbouring small scale blocks (microblocks) as well as the interdependence between the scale up values of macroblocks previously transformed. These outlines have conduced to the proposed interactive method: in each iteration corresponding to the upscaling of one macroblock, the solutions are ranked according a criterion based on a flow test and expressed on one objective function. In a second step, the macroblock corresponding to the minimum value of the objective function is selected. The process continue until all blocks are scale up. This method guarantee that the solutions are successively conditioned both to initial permeability values and/or scale up values obtained in previous iterations.
The performance of this method is illustrated in opposition with the classic approach by comparing the amount of flow in a local grid (each local grid include the set of blocks to come up with one value) using the small scale blocks and the large scale blocks. A second test is the comparison of the waterflood shape in a flow test using two opposite wells located in the small scale blocks and the large scale blocks using the flow simulator ECLIPSE 100.