Abstract

In the end of 2012, the breakthrough of 15 stages fracturing treatment of horizontal well-JiaoYe 1HF, located in Jiaoshiba block, Fuling gas play, Chongqing, China, with the post-fracturing gas production 203,000 m3/d (Lu, et al., 2013; Zhou, et al., 2013), which opened the new page of shale gas exploration and development in China. The reason of the success may be owed to the adaptable strategy and corresponding parameters so as to maximize Effective Stimulated Reservoir Volume(ESRV) (Jiang, et al., 2011; Jia, et al.,2012).

A systematic method was employed in this study which contains physical simulation in lab, numerical simulation, and fracturing fluid additives development as well. Firstly, a comprehensive formation evaluation was conducted such as rock lithology, pore throat size, porosity, permeability, rock mechanics, three dimensional stress, pore structure, maturity, total organic content, total gas content including free gas and absorbed gas, etc (Jia, et al.,2012). Secondly, a three axis laboratory test of fracture propagation physical simulation on a lot of large scale rock samples were conducted, from which the network fracture mechanism and correspondingly, the key control factors may be available consequently(Zhang, et al.,2013); Thirdly, a systematic laboratory tests of fracture conductivity for many conditions such as various fracture type and, proppant type, concentration and placement mode in different closure stress and time, etc. were conducted, so that the conductivity characteristic of network fracture may be obtained so as to utilize in the design of pumping schedule(Jia, et al.,2014); Fourthly, a new mathematical model of coupling flowing interference and stress shadow interference was put forward and a "W" type fracture distribution was correspondingly anticipated. After that, a new optimization model for well pattern and well space, fracture parameters and fracturing treatment parameters can be optimized simultaneously (Jiang, et al., 2013). Fifthly, alternately pumping mode of "spearhead acid, slick water, gel, slick water, gel……" and "70/140 mesh proppant, 40/70 mesh proppant, 30/50 mesh proppant "was put forward based on the object of main fracture net pressure during the course of fracturing treatment(Jiang and Jia, et al, 2011, 2013). Sixthly, a new flow back model was put forward and the relative flow back parameters such as shut-in time and flow back rate as well may be optimized correspondingly(Jiang, et al, 2013).

The above mentioned technology have been applied in a large scale (more than 200 wells) in Fuling shale gas play, therefore, expected results are obtained with the average gas production more than 300,000 m3/d, and the highest open flow capacity as high as 1,580,000 m3/d. Now, Fuling shale gas field is the largest one in China, its annual production is more than 5 billion m3.

Therefore, it has a great significance on the hydraulically fracturing technology in other lithology such as tight sandstone and carbonate reservoirs.

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