bluuebunny/crossref_metadata_2025_split huggingface dataset:
Experimental Study of Two Phase Pumping in Progressive Cavity Pumps
Authors: Martin A. M. , Kenyery F. , Tremante A. 
Published: December 2007

Abstract
Multiphase pumping has consolidated itself as the state of the art technology in crude oil transport for declining and marginal fields. Several types of pumps have been applied or developed for such service, opening a new research trend worldwide.
In this research we studied the progressive cavity pump performance with two-phase flow. Our aim was to obtain the pressure and temperature profiles along the pump's stator, and to observe its behavior under different sets of variables such as gas void fraction, rotational speed and Ap. The knowledge that can be acquired will be useful to estimate how flow conditions can be affecting the pump's life and the smoothness of the pump performance.
The results showed that for single-phase flow at low Ap the maximum pressure is not located at the pump outlet as it would be expected. The pressure distribution in the pump with two phase flow is completely different to the latter case, being found that within the pressure range of the experiment the cavities are kept sealed almost along the whole pump. For any point of operation the maximum temperature is found in the intermediate stages.
Use of Automatic History Matching and Geostatistical Simulation to Improve Production Forecast
Authors: Portella R. C. M. , Prais F. 
Published: December 2007

Abstract
The development of automatic history matching techniques is receiving much attention recently. The methods are becoming increasingly faster making practical applications possible. In general, these methods provide a single solution that matches the observed data, but as the solution of inverse problems is not unique, there is no guarantee that production forecasts made with the adjusted model will produce good results. Thus, it would be desirable to know the confidence interval of the adjusted model. The methodology presented in this paper combines a history matching technique with geostatistical modeling to provide equiprobable reservoir images that take into consideration production data. The method starts by doing an automatic history matching using existent production data. The automatic history matching technique used in this paper is based in simulated annealing, and it uses pilot points to reduce the number of adjusting parameters. The resulting adjusted model provided by this technique is then used to generate geostatiscal realizations. Using values of the pilot points and the original existent data as conditioning points, several geostatistical images are generated. Then, these images are used to obtain the confidence interval of production forecasts by performing a flow simulation in each one of them.
Although the computational cost of the methodology is high, the information about the uncertainty of the production forecast that it generates compensates the additional time necessary to obtain the results. In addition, the final reservoir images obtained with this technique will be much closer to the real reservoir than images generated using only static information of properties in the wells. The paper also shows a complete example where the adjusted parameter is the permeability field of the reservoir. This methodology could be applied with any optimization method, and it provides an excellent way to access production uncertainty.
Pore Network Model of a Bubble-Driven Drainage Process
Authors: Alvarado V. , Rodríguez A. A. 
Published: December 2007

Abstract
A network model has been developed to study a drainage process driven by the growth of gas bubbles in the span of viscous liquid in a disordered lattice. This medium is a two-dimensional network made up of spherical pore-bodies connected by cylindrical pore-throats. The pore-bodies act as fluid containers, while the pore-throats control fluid pressure drops and capillary pressure in the presence of liquid-gas interfaces. The fluid, at the initial stage of the simulation, is a homogeneous mixture of gas in solution and an incompressible liquid. Two stages of the process are included: site activation and growth of bubbles. Site activation occurs when the pressure of the liquid allows the release of trapped gas at the solid surface crevices. Growth takes place by bubble expansion that drives the liquid out of the system. Two pressure boundary conditions for the network are considered. The first one consists of a sudden pressure drop at the external lateral boundaries (and either periodic or no-flow boundary conditions at the top and bottom) from the initial equilibrium condition, which allows simultaneous activation of bubbles. A second condition is a linear pressure decline at the lateral boundaries, which leads to progressive site activation. We show gas bubble size distribution as a function of time and position. It has been observed a very strong dependence on the studied boundary conditions.
Laboratory Study of Gravity Drainage Mechanism in Fractured Carbonate Reservoir-Reinfiltration
Authors: Sajjadian V. A. , Danesh A. 
Published: December 2007

Abstract
In a well fractured reservoir that has a gas cap, after commencement of production the gas cap expands and the gas-oil contact (GOC) in the fracture system descends. The oil contained within the matrix of the gas invaded zone begins to drain down into the fracture system and into the lower matrix blocks, due to the force of gravity. Some of the oil that is drained out of the upper matrix blocks can reinfiltrate into the lower matrix blocks from the top or side surfaces and can flow down through the areas of contact between blocks.
In this study, data on a set of experiments that center on reinfiltration process are presented. The experiments cover fully saturated and desaturated blocks in vertical and inclined positions. The results of our experimental works reveal that the reinfiltration process depends mainly on the physical properties of the matrix block, the rate of oil supplied, and the drainage stage of the block.
When oil is trickled at the top of a desaturated block, initially due to an extra capillary pressure gradient the infiltration rate can be higher than the maximum drainage rate of the block. After some time the rate of the drainage approaches that of the infiltration and an almost steady state flow is established. At this condition, the lower portion of the block could drain oil, while the upper portion could be under infiltration process.
When the oil is directly supplied on the top of the vertical fracture, its crossflow from fracture to the adjacent matrix is demonstrated. In other words, under certain conditions the high conductivity vertical fractures are not necessarily the primary flow path of the supplied oil.
The purpose of this study is to provide a basic understanding of reinfiltration process in fractured porous media.
A Sand Erosion Model for Volumetric Sand Predictions in a North Sea Reservoir
Authors: Papamichos E. , Malmanger E. M. 
Published: December 2007

Abstract
Volumetric sand production data from a North Sea reservoir are interpreted with respect to the applied drawdown. Two sand rates are identified, one related to the increase of the drawdown and one to the magnitude of the drawdown. A sand erosion model is presented and used for predicting the field data. The model results compare satisfactorily with the field observations.
The Diagnosis, Well Damage Evaluation and Critical Drawdown Calculations of Sand Production Problems in the Ceuta Field, Lake Maracaibo, Venezuela
Authors: Vásquez H. A. R. , Sánchez D. M. S. , Yánez R. L. , Poquioma W. , Rampazzo M. , Chirity K. El 
Published: December 2007

Abstract
A geomechanics based methodology was utilized to analyze sand production problems as well as the amount of damage caused to the wells of the Southern Area 2 sector of the Ceuta field in Lake Maracaibo, Venezuela. Sand production in this field was not originally expected since the reservoir is composed of a well consolidated sand at depths larger than 16,000 feet and with rocks having an unconfined compressive strength larger than 6000 psi. Geomechanically speaking, sand production is caused when the destabilizing stresses on the formation are larger than the resistance due to formation strength. However, certain well operations can affect the destabilizing stresses as well as the formation strength. Therefore geomechanics must be used together with proper operational procedures because many operational details can also have a profound effect on the occurrence of sand production. One of the most important factors has to do with the production practices involving proper choke sizes and excessive choke changes. Sand production data gathered in the Ceuta field was analyzed using a geomechanical framework of understanding to predict well damage and problems during choke changes. The data defines 3 different stages of sand production for wells in this field. Each stage has a particular behavior and different problems associated with them. The sand production data was integrated together with the fluid production data to calculate the amount of accumulated sand production. A simple spherical model was developed to calculate cavity size around the casing utilizing the accumulated sand production. It was found that a well could produce large quantities of sand before total well failure. Total well failure appears to be related to the size of the cavities around the casing which leave it unsupported and also to erosive damage to the casing done by the sand laden fluids. The sand producing data was then used to diagnose the stage at which the sand production problem occurs and to change choke utilization practices in order to minimize sand production. Special laboratory geomechanical tests on core from the area and full wave sonic logging information was used to generate a model which calculates the critical drawdown for the problematic sands. Critical drawdown control has been the solution for most wells. Some other solutions such as hydraulic fracture and highly deviated wells in the correct direction have also been utilized.
Case History: Well Completion and Servicing Strategies for the Hibernia Field
Authors: Wylie Glenda , Maier Rod , Shamloo Said , Huffman Micky , Downton Neil 
Published: December 2007

Abstract
Offshore field development includes not only planning for appropriate well completion designs but also implementing in such a manner that production and economic goals for all stakeholders are realized. Consideration must also be given to operational support functions so that their administration will meet the project needs without compromising environmental, regulatory or safety standards. Often, a multidiscipline team approach offers the best method for developing the solutions needed to accomplish all the objectives. In this paper, Hibernia Management's approach to well development, completion and servicing strategies are discussed. Initial completion strategies were required to meet the designated design criteria of maximum well deliverability, minimal well maintenance, well servicing costs, and finally, minimal overall field-life-cycle costs. To comply with these stringent requirements as well as future needs, the downhole configuration would have to facilitate future non-rig workovers, recompletions or redrills, and have the flexibility to allow incorporation of future technological advances or changes in reservoir management.
In reviewing all options, minimizing overall field-life-cycle costs and the number of potential workovers were to be given primary consideration. Also of significant importance was the need to provide a zonal recompletion method as it was felt that the need for selective isolation of different zones would be needed to maximize recovery throughout the life of the wells. Completion strategies, the completion configuration, pre-installation shop tests, personnel training, completion servicing considerations and other challenges such as a "green field site" and rig requirements were reviewed; from these analyses, operational strategies were developed.
The initial completion installations were successful. The first two wells flowed approximately 40,000 BOPD and are Canada's highest producing wells recorded to date!
Development of a True 3D Hydraulic Fracturing Simulator
Authors: Yamamoto K. , Shimamoto T. , Maezumi S. 
Published: December 2007

Abstract
The recent development of horizontal and deviated borehole drilling technology in oil and gas wells requires hydraulic fracturing simulators which can take the three-dimensional formation of fractures into account. The authors have developed a fully coupled modeling of fracture opening and injected fluid flow for the three-dimensional formation of hydraulically induced fractures. The simulation can deal with the entire process of hydraulic fracturing including the post-shut-in process. A three-dimensional Displacement Discontinuity (DD) formulation for an elastic medium is used to model the relationship of fracture aperture and stress around the fracture. This formulation allows the simulator to deal with three-dimensional fracture propagation including bending and twisting of the fracture.
Fracture propagation based on the linear elastic fracture mechanics model, non-Newtonian behavior of the fracture fluid, and proppant transportation are modeled in the simulator. Fracturing processes including the post-shut-in process are calculated so as to satisfy the equilibrium of injected fluid volume, fracture volume and leak-off volume.
The numerical fracturing simulator can be used as a platform for studying the behavior of complicated hydraulic fracturing processes, and as a tool for the optimal design of hydraulic induced fractures.
Stochastic Reservoir Modeling of Sand GS - 8: Gandhar Field, Western India
Authors: Jain A. K. , Mathur A. D. , Taneja H. R. 
Published: December 2007

Abstract
Gandhar field in western India has multiple sandstone layers of Middle Eocene age. These layers, designated as GS-1 (bottom) through GS-12 (top), are separated by distinct shale markers, thus promoting different layers to reservoirs of separate identities.
GS-8 sand of this field, which is the focus of present study, has traditionally been an oil producer. A recent well has now produced gas from the bottom part of this sand. This has created doubts about the presence of a local gas cap, about the fluid content of GS-8 and its distribution and about the vertical and lateral continuity of the permeable facies.
The study addresses these issues with an objective to frame reservoir description of GS-8 in order to evolve an effective exploitation strategy. It is based on stochastic modeling of electrical log data as fundamental input.
Probability distribution maps of log derived lithofacies and their petrophysical characters have been prepared, based on average log parameters at one meter interval, starting from the base of GS-8 upto a height of fifteen meters. These distributions help visualize spatiotemporal evolution of the whole GS-8 unit. Fifteen meter thick pack of these maps, placed on top of one another in stratigraphic order, has further been sectioned along closely spaced north-south and east-west lines. These sections have been found to be of great use in displaying the micro-stratigraphic sequences and delineating various flow units of GS-8 layer.
The sections reveal that the sand bodies are isolated, and are encased within the adjacent shale layer in many pockets, giving a complicated picture of the reservoir. They also clarify that, by and large, the GS-8 unit is divisible into two sub units, GS-8A (lower) and GS-8B (upper). The deposition of these sub-units is area specific, and they are separated by a low porosity zone.
Another revealation of the study has been that GS-8 layer, as a whole, is not a closed system insulated by a shale layer, and at places it is connected with overlying layer GS-9. The study has helped extend chrono-stratigraphic boundary between layers GS-8 and GS-9 at those places (which otherwise had been difficult), within lithofacially homogeneous reservoir facies.
Application of Grey System Theory to Gas Pool Prediction of 3D Seismic Data prior to Drilling
Authors: Changrong Lin 
Published: December 2007

Abstract
Using 3D seismic data to predict the oil and gas situation before drilling is of benefit to improving the ratio of successful drilling. Owing to the complex situation of petroleum geology, especially in cases of limited data and uncertain information, a novel solution is necessary.
In this paper, a novel technological theory, grey system theory, is introduced. The investigation of the stratum containing gas underground is completed via grey modelling, grey prediction and grey relational analysis. So, a quantitative grey procedure is introduced into the field of petroleum geology, normally a field investigated with qualitative description.
Grey system theory, was created by professor Deng Julong in 1982. A number of projects in different fields have been successfully completed using grey system theory, procedures and concepts. Here, the grey system theory is successfully used in a number of wells prior to drilling, The results of experiments are very satisfactory --- a total of 16 wells in 10 structures are predicted prior to drilling. The ratio of successful drillling is over 87%. Therefore, the grey system theory and methods attract attention for predicting and analysing oil and gas status before drilling.
Planning of Deepwater Drilling Operations with Aerated Fluids
Authors: Nakagawa E. Y. , Santos H. , Cunha J. C. , Shayegi S. 
Published: December 2007

Abstract
Although underbalanced drilling (UBD) has been used for many years, with more than 11,000 wells drilled underbalanced in Canada and the USA, this technique has been almost exclusively applied to onshore fields. Despite a few experiences offshore, questions related to safety, logistics, and equipment placement have kept offshore UBD restricted to fixed platforms or jack-up rigs. Nevertheless, the industry trend towards offshore deepwater production has made it imperative to make this technology technically and economically viable for use in floater units as well.
This paper describes current efforts being made by a group of companies involved in a Joint Industry Project (JIP) focused on planning and drilling a deepwater offshore well from a semi-submersible platform using nitrified fluid. Although the well will not be drilled underbalanced for this first well, it will be the first well to be drilled from a floating vessel using a gasified fluid.
The main issues addressed in the project include: field data analysis, drilling hydraulics and cuttings transport experiments and modeling, software development and validation, formation damage experiments and modeling, wellbore stability failure mechanisms, operational procedures, safety issues, equipment development and/or conversion and benefits quantification for the process. Several of the key issues are discussed in this paper.
Convergence of Key Technologies in Multilateral Well Construction
Authors: Ben Lim S. B. , Good Alan 
Published: December 2007

Abstract
The authors in this paper attempt to propose a model for identifying and selecting key technologies that would add value to the return on investment on a Multilateral well. The last few years have seen the proliferation of Multilateral (ML) wells in the Asia Pacific region and elsewhere in the world. On a parallel front, the oil industry has experienced the introduction of key technologies such as geosteering, rotary steerable "automated" drilling tools, sealed junction technologies, non damaging drill-in fluids, re-entry access completion equipment in development projects worldwide. In conjunction with the development in junction classification and junction construction, it has been noticed that these key technologies in areas of drilling, completion and well planning are increasingly being applied to the construction of Multilateral wells.
This paper traces the historical outline of the technology development in Multilateral wells, and it documents the milestone introduction of key technologies that will greatly enhance the return on investment in a Multilateral well. The Authors in this paper will propose a model for identifying the technology needs and the potential enhancement in cost savings for applying key technology. The benefits and cost effectiveness of these technologies are discussed in this paper, and the inevitability of Multi-lateral technology converging with other key technologies are highlighted.
Stochastic Modeling for the Heterogeneous Anisotropic Reservoir System by Using Geostatistics
Authors: Lee Dongseong , Kang Joe M. 
Published: December 2007

Abstract
We present a method to characterize a heterogeneous anisotropic reservoir by integrating both core data and well testing data.
To characterize a heterogeneous anisotropic reservoir, we introduce coordinate transformation which convert the anisotropic reservoir into the isotropic one. Anisotropy can be expressed by grid block permeability or correlation length or both of those. For each case coordinate transformation function is developed respectively. On the transformed domain simulated annealing is employed to optimize the permeability field. Then final heterogeneous anisotropic permeability field is obtained by inverse transformation. To predict the breakthrough time, the simulation of water flooding is performed stochastically on the several types of characterized anisotropic fields.
The results show that trend of pressure and permeability image of the characterized field is close to that of the base field. The breakthrough time can be predicted more accurately within a confidence interval when water flooding is simulated on the characterized heterogeneous anisotropic reservoirs. The proposed method can reduce the reservoir uncertainty significantly since both well testing data and geological data are used.
Application of Spectroscopy C/O Logging in Tempino and Bajubang
Authors: Mas C. , Adi S. , Dewati R. 
Published: December 2007

Abstract
C/O logging has been used successfully to evaluate feasibility of water flood program in the 60 years old oil fields Tempino and Bajubang. A total of 25 wells were surveyed during April 1994 to August 1995. Combined with the neutron logs and swab tests, the logs were used to monitor behind casing saturation for water encroachment, confirm the existence of gas cap and solution gas drive, confirm that the fault blocks are isolated, substitute for the lack of open hole log data and lithology evaluations and to evaluate the potential of water supply sand. Results of evaluations in Tempino and Bajubang are in the implementation process. Positive responses are observed in the fault blocks where the water flood has been fully implemented. Logging program design is critically important to the interpretation process. Recommended procedures are discussed.