bluuebunny/crossref_metadata_2025_split huggingface dataset:
Breakouts: Physical and Numerical Modeling
Authors: Villarroel F. M. , Júnior E. V. , Rabello G. F. , Bloch M. , de Azevedo V. A. 
Published: July 2010

Abstract
In-Situ stress knowledge is very important for the oil industry, affecting well location, drilling, stimulation design, and production rates. Breakout detection from the interpretation of wellbore logs, including geophysical measurements, is one of the most applied methods for estimating the horizontal in-situ stresses. This paper presents laboratory tests for breakout simulation with a synthetic sandstone (0.3 × 0.3 × 0.3 m), performed in a large poliaxial cell. The testing apparatus was able to show breakout formation in a central hole in the block, simulating a vertical wellbore. The experimental results were compared and confirmed by numerical simulation through finite elements using a commercial software — ANSYS™ (ANSYS, 2007), and analytical calculations. The stress contrast at the onset of the breakout failure, determined from the experimental results, agreed within 4 % to the value computed from the numerical and analytical analyses.
Pressure Falloff Test Interpretation for Leakage Detection during CO2 Injection in a Deep Saline Aquifer
Authors: Ehlig-Economides C. A. , Anchliya A. , Song B. 
Published: July 2010

Abstract
Geological sequestration of carbon dioxide in deep saline aquifer is proposed as an option for mitigating CO2 emissions into the atmosphere, but multiwell injection into the same aquifer will cause pressurization. While many papers have considered long term CO2 trapping, few have addressed the role of pressure monitoring during injection as a way to ensure that the injection pressure does not exceed a regulated value below the fracturing pressure.
This work provides models for the injection falloff response that can be used for permanent pressure gauges installed at the injection interval for aquifer characterization and, in particular, for CO2 leak detection. A three region analytical composite reservoir model with sealing or constant pressure outer boundary is used to model numerically simulated falloff data for CO2 injection from a hypothetical 500 MW coal power plant. The analysis shows that regular falloff tests can monitor the advance of the dry zone and provide a reasonable estimate for the average aquifer pressure for the well injection area. The latter can be used for material balance, and simulations show that the behavior of the average pressure versus time is sensitive to the presence of a leak. Furthermore, it may be possible to determine whether the leak is located in the dry zone, two-phase zone, or the unswept brine zone.
Pressure behavior in CO2 storage aquifers has been neglected thus far in the literature. In reality, analysis of successive pressure falloff tests easily distinguishes over time whether a well is injecting into a limited volume exhibiting pseudosteady state behavior, an open aquifer with constant pressure support, or an effectively infinite aquifer. This paper spells out why pressure monitoring makes sense during CO2 injection.
Learnt from Formation Damage Problems to Design Selection of Produced Water Treatment for First Full Field Development Steam EOR Oman
Authors: Nengkoda Ardian , Habsi Mohd , Salmi Ahmed , Annamalai Ilangovan , Ahmed Dilshad , Sariry Sameer , Hadhrami Hamoud 
Published: July 2010

Abstract
The X field of Oman is a highly fractured carbonate field. The main oil bearing reservoir is the Shuaiba/Kharaib formation. Full development of the field will result in large water production that will have to be disposed off. Plan is to inject the produced water into the Al Khlata sands. The availability of sufficient water disposal capacity is a crucial element of the X steam project. If this capacity is constrained, water production from the X field is limited and it may not be possible to maintain the oil rim at the completion depth of the fracture rim producers. This may cause the oil production of the whole field to be deferred. For the base case, the total forecasted water production ranges from 63,000 to 74,000 m3 /d for 30 years. During pilot plant operation in year 1998-2000 and cold production, the formation damage and loss injectivity have been reported at produced water disposal wells. The main objective of this study is to ascertain the cause of rapid injectivity loss and input design for facilities selection. The assessment are cover the oil and solid particle size, fluid chemistry and compatibility, suspended solid in disposed water, the impact of oil in disposed water, fine migration (critical velocity test) and proper produced water treating facilities selection (equipment and technology).
Impact of Fluid Distribution on Scale Inhibitor Squeeze Treatments in Pattern Floods and Fractured Wells
Authors: Rakhimov A. , Vazquez O. , Sorbie K. S. , Mackay E. J. 
Published: July 2010

Abstract
The most common method for preventing scale formation in the well completions is by applying a scale inhibitor (SI) squeeze treatment. Near-well squeeze treatment models generally assume that the flow pattern around the well is radial. Although, this assumption may be reasonable in most scenarios, this paper investigates whether strictly non-radial flow patterns around the well have a major effect on the squeeze treatment.
Sensitivity calculations were performed to identify the impact of waterflood patterns such as Two-Spot, Five-Spot, Line Drive, etc. on the squeeze treatment lifetime in vertical production wells. The second part of the project then continued the study of the impact of flow patterns in fractured vertical production wells. The outcome is that scale squeeze treatments initiated at the same watercut appear not to be impacted by the various flood patterns studied. However, investigation showed that fractured wells typically have longer squeeze lifetimes in comparison to non-fractured wells.
Calculations show that for fractured wells, inhibitor adsorption on the face of the fracture itself has no impact on the treatment lifetime; the longevity of the squeeze is determined by the inhibitor adsorption in the matrix rock outside the fracture. The benefit a fracture brings is in terms of propagating the SI further from the well than would occur in an unfractured radial treatment. In the fractured well the inhibitor is then more greatly retarded by contact with rock over a greater distance than would occur in a matrix only radial treatment. Sensitivity calculations were performed to identify the impact of fracture length.
Hydrate Formation Conditions of Natural Gas with High Content of Carbon Dioxide and the Calculation Model.
Authors: Sun Ruiyan , Li Changjun , Yu Sheng , Wang Shigang , Sun Ouyang , Liu Enbin 
Published: July 2010

Abstract
In view of the natural gas with high content of carbon dioxide in Jilin oil field, this paper carried out experiments on hydrate formation conditions and studied the calculation model. Hydrate formation conditions of natural gas with high content of carbon dioxide were measured by using DBR device, and the formation temperatures of hydrate were obtained in the pressure range 0.5~15MPa. The molarity of carbon dioxide was 10% ~ 90%. Hydrate formation conditions of natural gas with high content of carbon dioxide were calculated by using vdW-P model and Chen-Guo model. The results show that: the calculation error of both models were more than ±2☐. With the increasing CO2 concentration in the natural gas, the calculation error of vdW-P model increased, but the Chen-Guo model's reduced. In general, the Chen-Guo model is superior to the vdW-P model. Based on the experimental data, the Chen-Guo model was improved. The results of improved Chen-Guo model agreed well with experimental result. The improved Chen-Guo model has high prediction accuracy, satisfies the engineering calculation, and has value popularized and applied.
A Case Study of High-Pressure, Light-Oil Steam Flooding in A Low-Permeability Reservoir
Authors: Shuhong Wu , Zhongyi Zhang , Yongbin Wu , Dehuang Shen , Yu Qian , Fujun Qiao 
Published: July 2010

Abstract
Steam flooding in heavy-oil sands has been well characterized over last decades as a mature technology, and while steam has been injected into light-oil, low-permeability sands almost as long, the mechanisms and effectiveness of this process are much less understood because of the complexities of flow in these sands and high pressure steam injection. This paper examines thermal recovery in such reservoir using both physical and numerical simulation and also describes the performance of pilot test in Daqing oil field.
In regard to recovery mechanisms, wettability alteration, interfacial tension and threshold pressure gradient decline contribute to higher oil displacement and swept efficiency. Vaporization, viscosity reduction, thermal expansion and relative permeability variation accounts for over three quarters of incremental recovery in steam flooding. As a consequence of high-pressure steam flooding five fluid banks form: steam bank, distillate bank, hot water bank, condensate bank and cold water bank, in which steam bank is much smaller than high temperature region. Hence, it is substantially different from shallow heavy-oil situation where both of them are almost similar in size.
This paper details a pilot test in a low-permeability reservoir with depth of 800m, an average permeability around 8 md and a typical porosity of 16%, oil viscosity roughly of 40mpa.s. Waterflood began in 1990 and suffered from low injectivity, poor sweep, and injector-to-producer linkage. These factors tended to degrade waterdlood's effectiveness. An attempt of steamlfood has been used to enhance recovery since 2005. The pilot test shows promising results. The response to steam injection is prompt and significant. The injectivity is doubled and productivity is almost tripled. The oil-steam-ratio is around 0.3. The incremental recovery is predicted to be over 10%. And now, field operator is considering expanding the pilot program to a much larger region.
A Innovative Technology to Extend the Borehole Section in Gas Drilling
Authors: Hongchun Huang , Ning Sun , Jinhai Yu , Jie Feng , Hui Wang 
Published: July 2010

Abstract
Air/gas drilling is an acknowledged practical technology for its significant advantages in rate of penetration enhancement, lost circulation prevention and hydrocarbon reservoir protection. Air/gas drilling technology, however, can only be applied to dry formations in nowadays. When formation drilled water produces, air/gas drilling needs to be converted to mist drilling, foam drilling or liquid mud drilling, which can result in dramatic reduction of drilling speed. This problem becomes the bottleneck to further extend gas drilling applications in a larger scale in China. Aiming at solving water influx problems in the field application of gas drilling, a new technical method was proposed through in-house research. The water production zone and water cut of drilled formation are predicted using the seismic, logging data and the seepage mechanics theory. When the drilled formation begins to produce large volume of water, a material (water absorbent) is injected to promptly absorb the downhole produced water and remove it out of the wellbore, so as to maintain the normal gas drilling. Furthmore, as drilling goes into well sections with incompetent or large water-cut formations, the expanded tube is employed to mechanically plugging the complex borehole section, which enables the air/gas drilling to be continuecd. Based on this solution, a water absorbent with high efficiency was screened out. Related operational procedures of absorbent injection and expanded tube plugging were studied. Field pilot test shows that with the technique, the borehole section in air/gas drilling can be extended, making the best use of air/gas drilling to increas penetration rate, which hence plays an important role for promoting the use and the advancement of air/gas drilling technology.
Horizontal Well Production Technologies in the Thin-Bedded, Bottom-Water Reservoirs in Luliang Oilfield, China
Authors: Jin Huo , Guoxin Shi , Jianguo Lu , Linxiang Sang , Jun Shi , Jianhua Tan , Yi Zhang , Guangxu Fan 
Published: July 2010

Abstract
Hutubihe formation in Well block Lu-9 of Luliang oilfield, Junggar basin of Xinjiang, China is characterized by special thin-bedded, low-amplitude reservoirs with edge and bottom water. Non-producing reserves are mostly distributed in small thin-bedded lenticular sand bodies with edge and bottom water. The average reservoir thickness is less than 3m. Therefore, the water-oil contact relationship is relatively complicated and it is difficult to produce oil from vertical wells. As a result, the economic benefit is poor. Based on the detailed reservoir description and dissection of single oil-bearing sandbodies, classification of flow units, accurate identification of net pay and low-resistivity oil-water zones, pilot horizontal-well production is carried out. Meanwhile, research on accurate well track control, reasonable horizontal section length, well placement pattern and injection-production well spaces are performed. Thus, a set of horizontal well production technologies are established for this kind of reservoirs. On the basis of optimization of non-producing reserves of different oil-water relationships and different geological characteristics in the range of an 800m interval, 110 horizontal wells are allocated with the newly-established productivity of 400 thousand tons. The producing extent of reserves has been improved from 50.7% to 83.2% and pretty good effects have been gained.
Formation of Carbonyl Sulfide during Molecular Sieve Dehydration Process from High Sour Natural Gas in China
Authors: Yan Tu , Honggang Chang , Jinlong He 
Published: July 2010

Abstract
Molecular sieves with high silica content are usually selected for dehydration of sour natural gas because of their tolerance to H2S. Some special acid-resistant molecular sieves can maintain their dehydration capabilities over long period.But carbonyl sulfide (COS) is formed by the reaction of H2S and CO2, which is catalyzed by molecular sieves during natural gas dehydration.
The overall development program at Luojiazhai Gas Field(high sour gas contents) of petrochina southwest oil and gas field company chose the molecular sieve adsorption process to dehydrate sour natural gas, but the gas field has not been developed up to now.A set of of the molecular sieve adsorption equipments has been applied at Liangfeng gathering station of Wanzhou city. This is the first plant for high sour gas dehydration using molecular sieve in China. The wet natural gas contains 9% H2S, 11% CO2 and 200ppmv COS. The dry gas flows to a natural gas treating plant to remove H2S and CO2 to meet pipeline specifications.
We found that the water dew points of the treated gas were always lowered to less than -10☐.But this molecular sieve displayed a certain extent of catalytic activity for the reaction converting H2S and CO2 to COS and H2O. The generated amount of changed greatly during operating cycle. The concentration of COS will rise while hot stripping gas moves through the bed.
So for sour gas dehydration and desulfurization, these data may prevent serious design errors. Molecular sieve manufactures were able to gain valuable assistance.
New Methods about the Productivity Contribution Evaluation and Development Features of Natural Fractures in Ultra-Low Permeability Reservoir
Authors: Xinquan Ran , Jiyong Zhao , Shuheng Li , Jianming Fan 
Published: July 2010

Summary
According to the data such as outcrops, cores, well logging with imaging, and thin sections, the natural fractures are developed in ultra-low permeability reservoirs. The fracture types are with tectonic shear fractures as the dominated which appear in groups and en echelon arrangement. Natural fractures are most developed in sandstone and siltstone, but rarely developed in mudstone.
The tectonic fractures show themself in four groups of the NE, NW, near EW and near SN orientations. Influenced by the heterogeneity of rock mechanics and the current stress field, fractures in NE-orientation are with wide opening and high permeability. Therefore the NE-orientation is the main flow direction of fluid in this area. On the basis of the traditional fracture description methods, a geological model of reservoirs considering the natural fractures is established with the help of modern fine reservoir description and fracture modeling techniques. The planar distribution laws of effective natural fractures that tally with production performance are determined by application of a numerical reservoir simulation inversion technique. A model considering natural fractures and non-Darcy flow is creatively established on the above mentioned basis. Quantitative evaluation of natural fracture and matrix's contribution to the individual well production rate has been conducted by using this model and the numerical reservoir simulation technique. The contribution rate of natural fractures obtained from the two methods to the average individual well production is 30%–40%. Research results show that the understanding of influences of natural fractures on development results of the ultra-low permeability reservoirs is deepened. Quantitive description of effective natural fractures and their assessment method of the contribution rate to the productivity have been preliminarily formed at the same time, which can be used for reference in the development of the same kind of reservoirs.
Studies on the Electroc-Catalytic Degradation of EOR Wastewater by Ce-Ti/TiO2 Electrode
Authors: Yi Zhang , Youyi Zhu , Desheng Ma , Dong Han , Dakuang Han , Shuying Wang 
Published: July 2010

Abstract
Enhanced oil recovery is the most effective method to produced oil from oil reservoir, during the enhanced oil recovery process, many kinds of chemicals, such as polymer and surfactants, are used, so the produced water (wastewater) is complexity and stability. How to treat the oily wastewater becomes an urgent problem in oil industry. So the feasibility and effective of electro-catalytic degradation of EOR wastewater was investigated in this paper. By sol-gel method the rare earth metal cerium (Ce) and titanium (Ti) doped TiO2 thin film electrodes were prepared. The surface topography, element composition and structure of the electrode of Ce-Ti/TiO2, which has the optimal effects for degradation of oily wastewater and polymer, were analyzed by SEM, EDX and XRD methods. The electro-catalytic effects and mechanism were also studied. The results indicated that the main process of electro-catalytic deoiling was electro-burning, and the acidic medium is favorable for oil and hydrolyzed polyacrylamide (HPAM) degradation. The removal rate of CODCr and oil content in the EOR wastewater reached 92.9% and 94.3% respectively. The removal efficiency of polymer was higher 20% than that of the advanced electrochemical oxidation technology, and the de-oiling efficiency enhanced about 8%~9%. After treatment by the electro-catalytic methods, the CODCr and oil content in the EOR wastewater meet with the Chinese discharge standard of the wastewater.
The Study of Development Mechanism and Characteristics for Kela 2 Abnormally High Pressure Gas Field
Authors: Tongwen Jiang , Weihong Zhu , Xiangjiao Xiao , Hongfeng Wang 
Published: July 2010

Abstract
Kela2 Gas Field is the main West-to-East gas transmission pipeline gas field with the feature of high geologic reserve, high well productivity, high reservoir pressure, high pressure coefficient, high structure angle and extremely thick reservoir and so on. Base on the main geologic features, has established the geological model fitting the gas reservoir. Through the further study of the geologic features and the development mechanism, has made the conclusions as follows: ①Because of the good quality of reservoir rocks, stress sensitivity has little impact on development effect. ②The static water body is about 5 times of hydrocarbon volume through geological evaluation, so the water drive energy is weak and has little effect on the field development. Thus the field can be developed in high recovery rate, and the reasonable recovery rate is around 4%. ③There is less interlayer interference between high and low permeability zones. Therefore, It is considered that commingled production should be taken for Kela2 gas field. Base on the conclusion, has builded up Kela2 gas field, which is the largest scale deliverability in China. The fundamental theory for Kela2's productivity evaluation and dynamic analysis is well applied to th the Dina and the Dabei gas field which is the similar abnormal high pressure character. Through the applicantion, has formed a systematic development techniques suitable for the submountain region with ultra deep and surpressure of Tarim basin.
UBD Brings about a Big Breakthrough for the Exploration of Algeria Block 350
Authors: Cunzhi Cheng , Benjing Dong , Zuokun Zhou , Jianli Zhang , Junfeng Ma , Qingfang Li , Zuokun Zhou , Guo Wei , Mingfu Ma , Chunshu Zhang 
Published: July 2010

Abstract
Algeria Block 350 is located in the northwest of the Oued Mva sub-basin in the Sahara Desert with an area of 8666km2. From 1972 to 2007, CFPA, Talisman, SSRP, Sonatrach, and CNPCIAE drilled in succession 10 wells in the block. However, all the wells failed to reach an industrial oil and gas production rate due to the high mud content in the tight and low-permeable sandstone reservoirs. Though the hydrocarbon detectors of two wells, Bel-E-1 and Meg-2, which were drilled by CNPC, showed the gas measurement values up to 900,000 ppm, the DST testing results were still far from expectation. In order to eliminate the impact of reservoir pollution caused by drilling fluids, series of stimulation operations such as pickling and large-scale fracturing (calculated crack length 75 meters) were conducted to well Bel-E-1 after it was cased. Nevertheless, the testing results only received 4.8 m3/d of oil and 5800 m3/d of gas, which were still below the threshold for economical benefit. By analyzing existing well data and testing results, experts believe that it is difficult to make an exploration breakthrough by using conventional drilling technology in such a reservoir with poor physical properties, so some other solutions are in need. After more than six months of in-depth research and repeated demonstration, CNPC decided to use underbalanced drilling technology to tackle the block's exploration problems, which has been proved entirely correct finally. On July 25, 2008, the underbalanced horizontal well Bel-Z-1 was tested with 24/64"(9.5mm) choke for the Devonian Siegenian layer, and a result of 9.71×104 m3 of gas and 15 m3 of condensate oil achieved under the WHP of 1314psi. This paper reviews challenges encountered in designing and constructing the well Bel-Z-1 and related solutions so as to share our experience with the industry.