Adaptability and optimal design of stimulation measures of low permeability carbonate reservoirs


Low permeability porous carbonate reservoirs in the Middle East have great potential for development, but their attributes are poor and seepage capacity is low. Hydraulic fracturing is one of the key technologies to unlock their commercial potential. It is of great significance for China National Petroleum Corporation to achieve the development goal of "high-speed production and rapid recovery". This paper aims at the problem of hydraulic fracturing mode optimization and large difference in productivity of single well after stimulation of the low permeability porous carbonate reservoirs. A demonstration of reasonable fracturing models based on a lot of experiments was carried out, and numerical simulations were used to optimize the fracturing process. The feasibility of fracturing low permeability porous carbonate reservoirs was verified by true tri-axial experiments,and the differences in fracture morphology between guar and slick water were clarified. Using downhole full-diameter cores to make rock slabs, the optimal proppant particle size and ratio are determined based on proppant conductivity experiments. Based on the mean value of the logging data of the S reservoir in an oilfield in the Middle East, a typical geomechanical model and numerical simulation model were established. To maximize the net present value of production, the fracturing parameters of low permeability porous carbonate rock were optimized and a matched fracturing process was formed. The results of experiments and numerical simulations show that, for low permeability porous carbonate reservoirs with few or no natural fractures, adding sand hydraulic fracture treatment can be used for these reservoirs stimulation. Relatively complex fractures can be formed in low permeability porous carbonate cores by hydraulic fracturing using a mixture of guar and slick water. Proppant conductivity experiments show that the larger particle size of proppant, the greater the corresponding conductivity under the same closing pressure. The particle size of the proppant should not be too small, and the conductivity of the proppant with a particle size of 70-140 mesh is less than 3 D·cm under the closing pressure of 30 MPa. The hydraulic fracturing performance is great if the number of fracturing stages is 6, the number of perforation clusters is 4, the fracturing fluid volume of each stage is 340 m3 , and each stage of proppant is 50 m3 . At the same time, field application results show that the hydraulic fracturing performance is good. The research results have a certain guiding significance for the high-efficiency development of low permeability porous carbonate reservoirs in the Middle East.

Key words:low permeability carbonate; fracturing experiments; numerical simulation; optimization design

Received: 2020-12-30

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Cite this article:杨菁, 刘辉, 宁超众. 低渗孔隙型碳酸盐岩油藏储层改造适应性及优化设计. 石油科学通报, 2022, 02: 204-212 YANG Jing, LIU Hui, NING Chaozhong. Adaptability and optimal design of stimulation measures of low permeability carbonate reservoirs. Petroleum Science Bulletin, 2022, 02: 204-212.