Shale gas water fracturing technology and China's constraints

Horizontal drilling and multi-stage fracturing of shale gas development is the core technology, but also the countries hope to break through the technical "bottleneck." Currently, large-scale  hydraulic fracturing  is the transformation of shale gas, the key to creating business capacity, but can not fully meet the actual needs of China. Compared with North America, China shale gas development more special geological conditions, scope buried deeper stratigraphic older.

China shale gas are located in Sichuan, Guizhou, Xinjiang, Songliao and other hilly, mountainous areas, water scarcity, transportation inconvenience, a large water fracturing can only meet the pre-trial development, when large-scale commercial exploitation of these problems will certainly as a constraint to the development of shale gas an important factor. Therefore, to explore shale gas development to adapt to China's technology system, the formation of independent property rights of the original innovation is the only way for China's shale gas development.


Most large-scale fracturing of shale gas wells need to get commercial production, shale reservoir stimulation technology in the process and scale are different from conventional fracturing. Shimizu fracturing is the most widely fracturing technology (also repeated fracturing and synchronize multiple fracturing with water-based liquid-based), but because the basic conditions around the world and reservoir characteristics of the differences are not all shale gas suitable for application of this technology. Fracturing technology choices to combine properties of shale geology, mineral composition, microstructure, sensitivity, brittleness, technical conditions, development conditions and other factors considered. North American in the job selection process summed up a set of methods fracturing techniques, mainly based on stratigraphic characteristics to choose the type of fracturing fluid displacement amount of sand and other processing. This selection method for shale gas development in North America achieved good role in guiding, but does not consider water supply capacity, and disturbing effects on the surrounding environment constraints such as operating conditions, it also brings some contradictions and problems.

Shimizu fracturing low cost, large-scale transformation, but also has its own technical limitations applied in China should be considered when the following questions:

A) water supply capacity of water-based fracturing (frac water, re-fracturing, synchronous fracturing) water consumption is huge. Production data show that over 75% of North American shale gas wells are yielding more than 10 fracturing, fracturing a repeat 1-2 times, the need to push open wells Week 60 m outside the reservoir. United States Environmental Protection Agency (EPA) statistics, in 2010 the average single-port shale gas wells in water 0.76 × 10 4 ~ 2.39 × 10 4t (depending on depth, horizontal length, fracturing scale), of which 20% to 85% compression After the stay in the underground. U.S. water resources are relatively abundant, roughly meet development needs. But Chinese water scarcity, it is difficult to meet the needs plenty of water.

2) restrict water reservoir properties of sand carrying poor performance, long horizontal sections and proppant easy settlement cracks, sanding, low efficiency, effective fracture length is more difficult to target. Compared with the U.S., China shale gas reservoirs low quartz content, carbonate and clay content, proppant embedment significantly after creep and fracture easily closed again after transformation, the long-term diversion capacity is insufficient.

3) large-scale equipment and operating constraints Shimizu fracturing and fracturing equipment needed are large-scale operations, number of tons of water and proppant mixed more need specialized compounding facilities, raw materials storage and transportation fleets dependent on a huge number of jobs, transport huge.

China shale gas exploration and development in Sichuan, Chongqing, Yunnan, Guizhou, Hubei, Anhui, Jiangxi, Jiangsu, Shaanxi, Henan, Liaoning, the new focus on these areas of large horizontal drilling and fracturing in addition to the above problems faced, but also by geological structure, topography, reservoir depth and other factors, these constraints will be constrained in the foreseeable future China's massive  shale gas  exploration and development. National Development and Reform Commission, "shale gas development plan (2011-2015)" called "to carry out a new fracturing fluid fracturing fluid treatment and reuse technology research, grasp for Chinese shale gas development stimulations core technology to improve shale gas well production ", while" saving water resources, "which indicates that for scientific and technological research, and explore new fracturing technology is the needs of the national strategic level. These problems are not only practical problems in China, North America, Europe shale gas development process also facing the same problem. Some counties such as the United States and France, because once fracturing pollution, water shortages and flowback fluid handling problems halt shale gas development. A large number of water supply problems also let the western United States, Canada and some European countries favor the development of new environment-friendly fracturing technology. Thus, in the process of shale gas development, explore new fracturing, development of technology has become a trend.