Enhanced oil recovery mechanism of low oxygen air injection in high water cut reservoirSpringer Science and Business Media LLC - Tập 8 - Trang 917-923 - 2017
Hu Jia, Shu-Pin Yin, Xian-Ping Ma
Whether air injection can extract additional oil in high water cut reservoirs is a big question. In this paper, long-core displacement experiment has been carried out to investigate the potential of low oxygen air flooding in high water cut reservoirs. Results indicate that implementing low oxygen air injection has potential to improve oil recovery in high water cut light oil reservoir. The reservoir with higher matrix permeability and or lower reservoir permeability contrast ratio is desirable to achieve higher oil recovery factor. In addition, the oil recovery factor for water/gas alternate injection (WAG) strategy is higher than that of continuous low oxygen air flooding. And the WAG strategy has the ability to delay gas breakthrough compared with the strategy of continuous low oxygen air injection under same experiment condition.
Numerical simulation of superheated steam flow in dual-tubing wellsSpringer Science and Business Media LLC - - 2017
Fengrui Sun, Yuedong Yao, Xiangfang Li
In this paper, a novel model is presented to estimate the thermophysical properties of superheated steam (SHS) in dual-tubing wells (DTW). Firstly, a mathematical model comprised of the mass conservation equation, momentum balance equation and energy balance equation in the integral joint tubing (IJT) and annuli is proposed for concentric dual-tubing wells (CDTW), and in the main tubing (MT) and auxiliary tubing (AT) for parallel dual-tubing wells (PDTW). Secondly, the distribution of temperature, pressure and superheat degree along the wellbores are obtained by finite difference method on space and solved with iteration technique. Finally, based upon the validated model, sensitivity analysis of injection temperature is conducted. The results show that: (1) effect of injection temperature difference between MT and AT on temperature profiles is weak compared with that between the IJT and annuli. (2) Temperature gradient in IJT and annuli near wellhead is larger than that in MT and AT. (3) Superheat degree in both CDTW and PDTW increases with the increase in injection temperature in IJT and MT, respectively. (4) Superheat degree in IJT and MT decreases rapidly near wellhead, but the superheat degree in annuli and AT has an increase. (5) Thermal radiation and convection are the main ways of heat exchange between MT and AT. This paper gives engineers a novel insight into what is the flow and heat transfer characteristics of SHS in DTW, and provides an optimization method of injection parameters for oilfield.
A MINLP model for combination pressurization optimization of shale gas gathering systemSpringer Science and Business Media LLC - - 2022
Jun Zhou, Hao Zhang, Zelong Li, Guangchuan Liang
AbstractThe combination pressurization of the shale gas gathering system is one of the most common pressurization methods in the current engineering site, but it is mostly set by manual experience or simulation analysis, and thus the optimal pressurization scheme cannot be obtained. In order to optimize the pressurization mode of the shale gas gathering and transportation system, a mixed integer nonlinear programming model (MINLP) is established based on the existing pressurization mode of the shale gas field. The model takes the minimum total cost of the compressor unit as the objective function. Various constraints are also taken into account, such as pipe pressure, flowrate, compressor related, well and platform throttling, uniqueness for well and platform pressurization. Solving this optimization model can figure out the appropriate pressurization position, operating power, and compressor unit cost. An actual case for a shale gas block is applied to determine the combined pressurization scheme suitable for this production condition. The results show that the combination of more pressurization methods can meet the pressurization requirements under different production conditions. When both well and platform pressurization are considered, the optimized pressurization position is more concentrated, the number of compressors is reduced by two sets, and the total compressor cost is reduced by 99.28 × 104 Yuan, which reflects the advantages of combined pressurization in the pressurization of shale gas gathering and transportation systems.
Automating sandstone acidizing using a rule-based systemSpringer Science and Business Media LLC - Tập 4 - Trang 381-396 - 2014
AbdAllah S. Ebrahim, Ali A. Garrouch, Haitham M. S. Lababidi
An expert system for automating sandstone acidizing has been developed in this study. The system consists of six stages, which were built following an acidizing logic structure that is presented in the form of decision trees. The six stages consist of formation oil displacement, formation water displacement, acetic acid, HCl pre-flush, main acid, and over-flush stage. The acid blends recommended by the system are damage-type specific, and account for the compatibility between the injected acid and the in situ crude in order to avoid formation of asphaltene sludge, or emulsions. The acidizing expert system has been implemented as an online web-based application. Applicability of this expert system to acidizing design has been illustrated using three documented actual field cases spanning the Niger Delta region, Algyo Oil field in Hungary, and the Dulang oil field in Malaysia. For Niger Delta field and the Algyo field cases the expert system produced an optimal main acid job design with recommended pre- and post-flushes that are in perfect agreement with successful field treatment. For the Dulang oil field, in actual practice, an organic clay acid was injected for removing problems of fines migration in a reservoir that has a high calcite content, with a moderate amount of feldspar and chlorite clay. The acidizing expert system recommended a chelant-based acid, which is a recent innovation that is considered a more cost-effective acid solution for dissolving fines in presence of calcite and other sensitive clay minerals.
Research of a novel double cross-linking fracturing fluidSpringer Science and Business Media LLC - Tập 11 - Trang 2191-2197 - 2021
Yanrong Ge, Zhongcong Zhao, Xiaoliang Cheng, Tengfei Chen, Tao Liu, Xiupeng Guo
A kind of JDL-1 thickener for betaine hydrophobic association polymer was prepared by aqueous solution polymerization of mixed micelles, AM, AA, AMPS and DM16 were used as raw materials, which was synthesized by redox initiator system. Friction tester and high-temperature rheometer were used to evaluate the resistance reduction and temperature and shear resistance of the thickener. The results show that the viscosity average molecular weight of the polymer prepared with AM, AA, AMPS and DM16 mass ratio of 70∶20∶5∶5 was higher than 12 million, and the dissolution time of the polymer was less than 3 min. When the surfactant is used for physical cross-linking, the apparent viscosity of the cross-linked fracturing fluid is larger than that of 60 mPa·s at 90 °C, 170 s-1 sheared 1 h; when metal cross-linking agent is used for coordination cross-linking, the apparent viscosity is larger than that of 80 mPa·s at 120 °C, 170 s-1 sheared 1 h. The drag reduction rate was 73%, the anti-swelling rate was higher than70%, and the damage rate was less than10%. The field trial was successful and confirmed the multifunctional effect of betaine-type hydrophobic associating polymer.
Prediction of gas pressure in thin coal seams in the Qinglong Coal Mine in Guizhou Province, ChinaSpringer Science and Business Media LLC - Tập 11 - Trang 4075-4086 - 2021
Jian Zhang, Yongqiang Zhang, Jilin Wang, Xiaobin Wen
Thin coal seams in mines usually lack gas data. Thus, preventing and controlling gas outbursts of thin coal seams are difficult. In this study, a coal structure index, which is used to express the damage degree of coal, was estimated by logging curve. In accordance with the contour line of the floor of the coal seam, structural curvature was calculated to express the complexity of the coal seam structure quantitatively. Subsequently, relationships among the burial depth, thickness, coal structure index, structural curvature were analyzed on the basis of the gas pressure of coal seam. The gas pressure values of the coal seams of Nos. 22, 24, and 27 in the study area were predicted by multiple linear regression (MLR) and were then verified and analyzed. The deviation rate of the MLR method was 6.5%–19.7%, with an average of 13.0%. The average deviation rate between the predicted value and the measured value was 11.6%, except for the measuring point of No. 2, which had a large deviation. Results show that the prediction accuracy of the aforementioned method is acceptable and has practical value in the prediction of gas pressure in thin coal seams without measured data. The results in the gas pressure prediction provide a basis for evaluating the risk of gas outbursts in thin coal seams.
Thiết kế và thử nghiệm bơm tiêm nước tiết kiệm năng lượng Dịch bởi AI Springer Science and Business Media LLC - - 2020
Jian Zhao, Yafei Dong, FU Jian-wei, Luhao Zhao, Yaning Zhang
Tóm tắtĐề xuất một bơm tiêm nước tiết kiệm năng lượng nhằm giải quyết vấn đề tiêu thụ năng lượng cao và hiệu suất thấp của các bơm tiêm nước truyền thống trong giai đoạn sau của việc khai thác mỏ dầu. Bơm thủy lực được sử dụng làm nguồn năng lượng chính để điều khiển chuyển động của piston thông qua van đảo chiều cơ khí, từ đó làm cho pít-tông chuyển động sang trái và sang phải, tăng áp suất nước trong xi lanh pít-tông. Đầu tiên, các tham số cấu trúc của bơm tiêm nước tiết kiệm năng lượng đã được xác định. Sau đó, phân tích động học của các bộ phận của bơm được tiến hành. Mô phỏng phần tử hữu hạn của xi lanh pít-tông và xi lanh pít-tông cho thấy rằng độ bền cấu trúc đáp ứng các yêu cầu. Mô phỏng động lực học của hệ thống thủy lực cho thấy áp suất đầu ra có thể đạt được áp suất đã định. Cuối cùng, một thử nghiệm thực địa đã được thực hiện tại mỏ dầu Giang Tô. Kết quả cho thấy thiết bị có thể đáp ứng yêu cầu tiêm nước của mỏ dầu.
Experimental investigation of a low-molecular-weight polymer coating agent for deep-sea oil and gas drillingSpringer Science and Business Media LLC - Tập 11 - Trang 2953-2962 - 2021
Xiaoxia Ren, Ran Liu, Zhe Ma
In order to solve the problems due to the thickening of drilling fluids at low temperatures caused by the use of high-molecular-weight polymer coating agents in offshore deep-sea oil and gas drilling, a low-molecular-weight polymer coating agent named PADA was synthesized with acrylamide, methacryloxyethyltrimethyl ammonium chloride, and 2-acrylamido-2-methyl propane sulfonic acid. The PADA polymer was characterized with Fourier transform infrared spectroscopy and gel permeation chromatography. The shale inhibition effects of the PADA polymer and associated mechanisms were investigated by shale recovery and expansion experiments, transmission electron microscopy observation, particle size and zeta potential analysis, and interlayer spacing measurements. In addition, the effects of the coating agent on the filter cakes and the low temperature rheological properties of bentonite mud were also tested, and the polymer biodegradability was evaluated. The results showed that the molecular weight of the PADA polymer was 265,000 D, which was significantly lower than that of the traditional coating agents. The PADA had similar effects as two typical commercial products CAP and HPAM on inhibiting the hydration dispersion of shales and performed better than another product PAM. The inhibition effect was achieved by the polymer absorption onto the clay particles through both hydrogen bonding and the electrostatic interactions. The viscosity of bentonite mud containing PADA was much lower than that of mud with other coating agents at 4 °C, so the serious thickening caused by traditional coating agents at a low temperature could be avoided. In addition, it is relatively easily biodegraded.
Reliability analysis for seismic capacity of casing stringsSpringer Science and Business Media LLC - Tập 10 Số 1 - Trang 47-52 - 2020
Jian Gao, Wentian Shi, Shujie Cui, Yongfeng Jiao
AbstractBased on the analysis of seismic intensity and randomness, an earthquake intensity probability model is built, and the relationship between seismic intensity and seismic acceleration is presented. The distribution law of casing parameters, including outer diameter, wall thickness, Young’s modulus and Poisson’s ratio, is described by analyzing the randomness of casing geometry and mechanical properties. With the setting up a mechanical model of the casing strings in earthquakes, and using the spectral modal analysis theory and the equivalent static load method, the calculation method of the equivalent load of casing strings under seismic action is studied. The limit state equations of various failure forms of casing strings in earthquakes are established. Based on the theory of structural reliability, the reliability model of casing strings under seismic action is built. The seismic reliability of casing strings is calculated, and the calculation results are verified by field data. The calculation results show that influence of earthquake on safety and reliability of casing strings is very serious for long service life oil and gas wells in areas where the seismic fortification intensity is high.
