bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Role of Geology in Stochastic Reservoir Modelling: The Future Trends
Authors: Tamhane D. , Wang L. , Wong P. M. 
Published: December 2007

Abstract
Stochastic simulation is a popular approach for the quantification of reservoir heterogeneity. From the geological viewpoints, however, the role of reservoir geology in stochastic models is diminishing in recent years. This paper reviews the major characteristics of the stochastic models, and geological knowledge is identified as the major missing element in the current practices of the simulation techniques. A detailed discussion of the meaning and usefulness of geological knowledge is given. We have also provided a list of future research directions showing how we can make use of conceptual geological models to bridge the gap between reservoir geology and stochastic simulation practices.
Reservoir Simulation for a Low Productive and Strongly Heterogeneous Carbonate Reservoir in the Arabian Gulf by Geostatistical Approach
Authors: Wannabe Kazuaki , Suzuki Satomi , Eto Koji , Samizo Nobuyuki 
Published: December 2007

Abstract
The reservoir simulation model for a low productive and strongly heterogeneous carbonate reservoir was constructed by upscaling the detailed geological model. First, geological model was constructed and the three dimensional distribution of petrophysical properties were generated by geostatistical approach. The absolute permeability and relative permeability endpoints were excellently correlated to the core data by the application of electrical facies (EF) grouping which was newly developed (Refs. 1 and 2). The successful history match was obtained by incorporating the high permeability streaks into the model to simulate the abnormal reservoir pressure trend. This high permeability streak was distributed by sequential indicator simulation (sIs) based on the combination of two types of possible log attributes.
Optimum Spacing of Multiple Stabilizers to Increase Critical Buckling Load of BHA in Slim Hole Drilling
Authors: Akgun Ferda 
Published: December 2007

Abstract
Cost effective drilling rate necessitates the adequate application of weight on the bit. Weight on bit is provided by means of Drill Collars (DC). As DC diameter gets smaller with the reduced borehole diameters as in the case of most slimhole drillings, their resistance against buckling, known as Critical Buckling Load (CBL), decreases. This may cause major drilling problems such as; undesired hole deviations, pipe failures and slow drilling rates.
Weight supporting capacity of DCs can be improved by the placement of stabilizers in bottom hole assembly (BHA). However stabilizer position in the BHA is one of the major factors, which effects the CBL of DCs.
In the first part of this paper a finite element method will be presented to assess the CBL of DCs. Then, CBLs of DCs with stabilizers placed at different configurations will be presented in the second part of the paper.
Oil Recovery Mechanisms of Alkali-Surfactant-Polymer Flooding
Authors: Arihara N. , Yoneyama T. , Akita Y. , XiangGuo Lu 
Published: December 2007

Abstract
The experimental study includes phase behavior tests, measurements of interfacial tension (IFT), and coreflood tests. Effects of alkali (sodium carbonate) additives on micro-emulsion phase behavior were determined for a reservoir oil. No emulsion phase was generated for low surfactant concentrations without alkali additives, while an emulsion phase was always formed with alkali. Measurements of the dynamic IFT revealed that when the alkali concentration is as high as 0.7–1.0 wt%, the IFT rapidly increases after about 100 minutes, which suggests that the system shifts from the middle to upper-phase equilibrium.
Based on tertiary alkali-surfactant-polymer (ASP) coreflood tests with surfactant and polymer concentrations of 1.0 wt% and 1200 ppm respectively, an optimum alkali concentration was confirmed as 0.2 wt% that allowed the highest recovery. Using the optimum ASP concentrations, another series of corefloods were conducted to evaluate the effect of remaining oil saturation at the start of ASP flood. Mobile oil helps alkali and surfactant slugs form an oil bank. In order to examine the oil recovery by high alkali and low surfactant concentrations (1.3 and 0.1 wt%, respectively), corefloods were conducted by changing the injection volume and scheme. Only a small incremental recovery is obtained with ASP slugs higher than 0.2 PV each. The injection scheme of polymer slugs is confirmed to be crucial for ASP flooding. Parallel coreflood tests as physical simulation of ASP flood in a two-layer system showed recovery performances complicated not only by permeability contrast but also by small-scale heterogeneity within inidividual cores.
Acceptable matches between coreflood experiments and one-dimensional flow simulation were obtained by modeling ASP flood with recovery mechanisms of the surfactant-polymer flooding.
Microbial EOR Laboratory Studies and Application Results in Daqing Oilfield
Authors: Zhang Yijiang , Xu Zhengshun , Ji Ping , Hou Weihong , Dietrich Forrest 
Published: December 2007

Abstract
Microbe inoculation of Daqing crude samples in the laboratory reduced oil viscosity, indicating microbe effectiveness. Field application of the same strains of microbes resulted in a thousand-fold increase in both concentration and total number of microbes in the water produced from the reservoir. The data proves existence of active, thriving microbe colonies in the reservoir in a manner not previously reported, compatibility between the microbes and Daqing oil in the reservoir, and propagation in the reservoir. The microbe detection method is reviewed along with microbe growing details in four wells. Overall field results in twenty-five wells are described, proving microbial EOR (MEOR) is suitable for use in Daqing Oilfield.
Well Abandonment—A "Best Practices" Approach Can Reduce Environmental Risk
Authors: Kelm Charles H. , Faul Ronnie R. 
Published: December 2007

AbstractWells are drilled and completed for a typical production life of 15 to 20 years. After a well is depleted, it must be abandoned so that the permeable intervals penetrated by the wellbore are isolated. For an abandonment to be successful, it must stabilize the wellbore and its associated annuli until geologic forces can re-establish the natural barriers that existed before the well was drilled. The isolation of the hydrocarbon-bearing intervals, overpressured intervals, uncemented annuli, and any freshwater intervals penetrated by the wellbore is critical to successful abandonment. The abandonment plan must be based on the types of fluids contained in reservoirs and the well's mechanical condition at the time of abandonment. Government regulations for well abandonment are minimal guidelines for abandonment, and should not be considered finite answers to environmental safety issues.This paper describes "best practices," concepts and techniques that operators should consider during abandonment planning, that will help ensure effective isolation within the wellbore.
Exploration and Production Operations - Waste Management a Comparative Overview: US and Indonesia Cases
Authors: Bansal K. M. , Sugiarto _ 
Published: December 2007

Abstract
Waste management programs in Exploration and Production Operations (E&P) are discussed in this report. Regulatory guidelines in Indonesia are briefly described and compared with the guidelines in the U.S. Waste treatment and disposal practices commonly used in the U.S. are also discussed. Pertinent regulatory guidelines for the use of some of these technologies in the U.S. are presented. This information was gathered to identify potential applications, based on the experiences in the U.S., for developing cost effective and environmentally sound E&P waste management strategies in Indonesia.
Wastes from E&P operations fall into four general categories: (a) produced water from production operations, (b) drilling, completion, and workover wastes, (c) associated wastes, and (d) industrial wastes. The largest volume waste generated by the oil industry is produced water. In offshore operations, produced water is treated to remove dispersed oil and is disposed of overboard in accordance with regulatory guidelines. In most onshore operations, produced water is treated and injected either for disposal or for waterflooding operations for secondary oil recovery. Produced water treatment technologies are not discussed in this report.
In Indonesia, most of the E&P wastes (e.g. drilling muds and oily sludges), except treated produced water, are categorized as hazardous and toxic wastes (B3 wastes). In offshore operations, treated produced water meeting regulatory guidelines (oil content &lt; 50 ppm for new installations and 75 ppm for existing facilities) can be discharged overboard.
In the U.S., the E&P wastes are exempt from Federal regulation as hazardous wastes under Resource Conservation and Recovery Act (RCRA) Subtitle C. Only waste streams that are unique to the industry qualify for exemption from Subtitle C. Industrial wastes generated by the E&P industry (such as solvents, paint etc.) are not exempt from RCRA.
Short Term Gas Demand Forecasting Based on Artificial Neural Network
Authors: Sato Ritsuo , Miura Kazuyoshi 
Published: December 2007

Abstract
Teikoku Oil Co. Ltd. (TOC) and NKK Corp. established a joint pilot project in 1994 in order to provide pipeline application and evaluation of NKK's gas hydraulic simulation engine (GASTRAN) and to co-develop a Demand Forecasting Model (DFC). When the pilot project finished in March 1997, a commercial system, called Support Operation and Monitoring Application of Pipeline Simulator (SMAPS), was installed in TOC's operation center.
The DFC, which is based on an artificial neural network architecture, has several advantages for sales forecasting especially as several dozen delivery points that have different sales patterns are connected to the pipeline network. The results from DFC can be easily used for scenarios in off-line simulation to predict future pipeline situations when it is attached to the SMAPS system. It automatically assists the pipeline operator by reducing his workload and evaluating operation plans.
Reducing Contaminant Uncertainty from First Principles
Authors: Frens Ante M. 
Published: December 2007

Abstract
Contaminants in gas reservoirs such as CO2 and H2S have large impact on field development. Although the contaminant concentrations are usually determined during the appraisal of a field, their distribution across the field often remains a key uncertainty with significant impact on the development cost (e.g. through the choice of materials for wells and facilities.)
In this paper we present an innovative approach to determine the distribution of two gaseous contaminants (CO2 and H2S) in different reservoir zones using the fundamental equations for diffusion. In the offshore carbonate gas field, that we describe in this paper, strong variations of CO2 and H2S levels in two of its three reservoirs zones were measured during appraisal of the field. The contaminants originated from thermo-chemical sulfate reduction deep below the reservoir and migrated through the aquifer into the reservoir build-up. The paper addresses two key uncertainties, which have great impact on the development planning:the contaminant levels of the third (deepest) reservoir zone which were expected to be higher than the levels encountered in the other zones;the risk of a contaminant level increase as a result of the liberation of dissolved contaminants from the aquifer when the reservoir pressure drops
Making use of the contaminant generation model and Fick’s 2nd law we determined the contaminant concentrations in the third reservoir zone. On the basis of that result we also show that an increase of contaminant levels as a result of the decrease of the contaminants solubility in the aquifer is no risk in this field.
These results allowed us to tie down these key uncertainties so that a significant cost saving for our wells and facilities could be obtained.
Application of EOS for Multi-component System Containing Heavier Hydrocarbons and Impure Components
Authors: Fujinaga Yoshinobu , Raijo Tsuyoshi , Fujita Kazuo 
Published: December 2007

Abstract
This paper presents effects of pseudoization of heptane-plus (C7+) component through the Constant-Volume-Depletion (CVD) process and influence of heavier fractions on phase behavior around a wellbore using a two-dimensional, two-phase compositional simulator of radial geometry. We investigated retrograde condensation behavior focusing near a producing well. It depends on selection of pseudo-component whether accurate phase behavior predictions can be obtained. Then we could predict more accurate phase behavior around a well in the reservoir by pseudoization and two-dimensional compositional simulator. We show several calculated results for cases where pseudo-components and other properties were changed.
Shale Stability: Drilling Fluid Interaction and Shale Strength
Authors: Lal Manohar 
Published: December 2007

Abstract
This paper presents main results of a shale stability study, related to the understanding of shale/fluid interaction mechanisms, and discusses shale strength correlation. The major shale/fluid interaction mechanisms: Capillary, osmosis, hydraulic, swelling and pressure diffusion, and recent experimental results are discussed. Factors affecting the shale strength are discussed, and a sonic compressional velocity-log based correlation for strength is proposed. Recommendations for modeling and improving shale stability are described, based on the current understanding of shale stability.
Water/Gas Shut-off Candidates Selection
Authors: Kabir A. H. , Bakar M. A. , Salim M. A. , Othman M. , Yunos A. 
Published: December 2007

Abstract
Selecting water/gas shut-off (WGSO) candidates with proper understanding is a critical step which influences outcome of any WGSO effort. Quite often an inexperienced engineer is perplexed by the task of having to find candidates for water/gas shut-off applications, whereas he/she has little idea as to where to start. He/she gets even more confused by selection criteria suggested by various authors, which aren't very clear.
In this paper a systematic approach for finding suitable candidates for WGSO applications is presented. Several techniques of WGSO candidate pre-screening are discussed. A step by step procedure which takes the engineer through a clear thinking process is suggested. WGSO candidates selection is best treated as part of his/her routine wellbore utility study (yearly event). Starting point is to conduct a well and reservoir performance review for the entire field based on all the data in hand. A list of required basic data which are helpful in this review is provided, as much of which as possible should be collated prior to this candidate selection exercise. Guidelines for further diagnosis to firm up WGSO candidates is also provided. Outcome of this study is a comprehensive list of all potential remedial work, of which WGSO is a subset. Having a complete picture of the well and reservoir performance helps an engineer understand reservoir fluid movement mechanism and therefore objectives of any remedial work becomes very clear. Then the engineer can review all products and services available in the market and can choose the most appropriate solution. Without a proper diagnosis and clear understanding of reservoir fluid flow pattern, any attempted solution will only be a guesswork and success rate will remain low.
Interwell Log Correlation Using Artificial Intelligence Approach and Multivariate Statistical Analysis
Authors: Lim Jong-Se , Kang Joe M. , Kim Jungwhan 
Published: December 2007

Abstract
A new approach to automated interwell log correlation using both artificial intelligence (AI) and multivariate statistical analysis is described. Correlation of wireline logging data is on the basis of a large set of subjective rules for pattern recognition that is intended to represent human logical processes. The data processed are the characteristics of the shapes extracted along log traces by object-oriented programming (OOP). Correlation of zones between wells is made by rule-based inference program. This method has the advantage over the conventional methods due to the capability of handling the shifting, thickening, and thinning strata in interwell correlation. Use of statistical techniques can obtain more reliable correlation results for complex geologic formation. The efficient and reliable pattern recognition for correlation can be established by using the first principal component log, since it has the largest common part of variance of all available well-log data. In addition, the electrofacies derived by selecting, weighting, and combing the multivariate well-logs can be used as an important information of lithology identification for more reliable correlation. Correlated results with logging data in the Korea Continental Shelf and oversea field show that this method can be used to make it more reliable and efficient to interwell log correlation rather than the traditional methods in which only one approach was adopted. It can be applied as an effective tool in planning the development and production strategy of the field.
A New Approach to Study on Thixotropic Properties of Waxy Crude Oils from Dragon and White Tiger Fields Offshore Vietnam
Authors: Thuc Phung Dinh , Van Bich Ha , Son Tong Canh , Vugovskoi V. P. , Le Dinh Hoe 
Published: December 2007

Abstract
In production and transportation of waxy crude oil as well as in practical Rheological studies of non-Newtonian liquids, it is very important to find and characterize its thixotropic properties. There are some ways to study this phenomenon, but nowadays the existing equations still can not quantifiably describe the time-dependent behavior of thixotropic liquids with acceptable accuracy using in this case an exponential or hyperbolic functions.
The authors have conducted the screening studies on rotational viscometer Rotovisco RV-20 with different kinds of waxy crude oils from JV "Vietsovpetro" fields offshore Vietnam. Based on the received experimental data and its analysis the authors have proposed a new equation showing a very good agreement between experimental and calculated data (the average deviation is less than 2%). The general time-dependence of shear stress at constant shear rate can be much more precisely expressed.
A new idea "the measure of thixotropicity" of liquids at given shear rate and temperature is also proposed to characterize the properties of thixotropic liquids.
A Viscoelastic Model for Polymer Flow in Reservoir Rocks
Authors: Garrouch Ali A. 
Published: December 2007

Abstract
In this work, steady-state flow experimental data have been analyzed for two commonly used polymers representing two generic classes: polysaccharides (xanflood), and partially hydrolyzed polyacrylamides (pusher-700) flowing inside bead packs and Berea sandstone. Oscillatory flow measurements have been used to compute the polymer solution's longest relaxation time (θf1). Steady-state flow experimental data for the two polymers combined with measured polymer viscous properties have been converted to average shear stress-shear rate data inside porous media. An average power-law exponent (n̄) is therefore obtained for the polymer flow inside the porous medium. Using θf1 and n̄, rock permeability (k) and porosity (ϕ) and fluid flow velocity (u), a dimensional number Nv (viscosity number) is calculated, and found to strongly correlate with the pressure gradient inside porous medium. This correlation is the basis for defining a viscoelastic model for polymer flow in porous media. The capillary-tube model is found to be adequate for only flow of viscous polymers with insignificant elasticity.
Laboratory Investigation of Polymer Producer TU-15A for MEOR Field Tests
Authors: Sugai Y. , Kishita A. , Hong C-X. , Enomoto H. , Chida T. , Zhou S-C. 
Published: December 2007

Abstract
Clostridium sp. TU-15A was isolated from the reservoir water from China jilin oil field. This microbe is a powerful polymer producer and expected for the effect on oil recovery.
This is the fundamental study on this microbe for the field trial and consists of following two experiments.
At first, cultivation experiments were carried out with TU-15A. This microbe reaches maximum phase at a day and increasing viscosity of the culture starts on second day. This result shows that the culture needs to be injected into reservoir within two days after inoculation. The relation between molasses concentration and the viscosity of this culture, which is pseudoplastic fluid is linear: about 40cP (at 10r.p.m) at molasses 4% and about 25cP at molasses 2%. From this result, it is possible to control the viscosity in reservoir. And adaptability to the environment in oil reservoir was investigated with following two incubation systems: micro-pore system and competition with indigenous microorganisms. TU-15A grew and produced polymer even under these conditions and there is not serious problem for cultivation in reservoir. In the examination with micro-pore system, this microbe grew slowly and reached maximum phase at forth day. This is an effective result for spread of culture in reservoir. In competition test with indigenous microorganisms, which were sampled from one block in Jilin oil field, the viscosity of this culture became low. Therefore it is necessary for TU-15A to test competition with indigenous microorganisms in selected target blocks again.
Secondly, flooding experiments were carried out with viscous culture of TU-15A with following two systems which were modeled with two sandpacks. One was five spot flooding pattern and the other was anisotropy of permeability. At the former experiment, two sandpacks total oil recovery was 73% after water flood and 12% of initial oil saturation after the culture injection. In the case of latter, two sandpacks total oil recovery was 68% after water flood and 15% of initial oil saturation after the culture injection. In both cases, high oil recovery were obtained from flow smaller sandpack and the change of flow caused these results by the culture injection. At the five spot flooding pattern, flow of injected fluid to flow smaller one improved from 22% at water flood to 47%: maximum of 56% and minimum of 38% and at the anisotropy of permeability, flow improved from 7% at water flood to 21%: maximum of 34% and minimum of 16% by injection culture. Moreover, the viscosity of culture was changed with two kinds of microbes in these experiments.
Jilin oilfield has an anisotropy of permeability and great effect is expected on oil recovery in this field with TU-15A from these results.