页岩气开发对川渝地区水资源环境的影响

On the impact of shale gas development on water resource and environment in Sichuan and Chongqing

目前中国页岩气已进行大规模商业开发,但页岩气开发对当地水资源环境造成一定的风险。通过川渝两地页岩气井场实地调查和取样分析,结果表明:一方面,页岩气开发总耗水量巨大,每口井用水量约32000 m^3;另一方面,水环境污染风险来自于:1)压裂返排液和钻井返排液,其成分复杂,盐度高,并含有多种重金属;2)钻进过程产生巨量的废油基泥浆和含油钻屑;3)页岩气开发地区,溶洞、裂缝、暗河发育,钻井过程易发生井漏或井喷;4)地面工程建设。因此,在页岩气开发过程中,必须精心施工,合理调配水资源,大力发展返排液处理技术,以便防止页岩气开发过程中过度消耗水资源,并避免水污染。

At present, China has commercially exploited shale gas in a large-scale. However, the shale gas development may bring risks for water resources and environments. By surveying water consumption, sampling and analyzing flowbacks from shale gas drill sites in Sichuan and Chongqing, it is shown that the total water consumption is huge for the shale gas development, i.e., each well consumes about32000 m3 of water. On the other hand, potential risks of water pollution come from several sections during shale gas development： firstly,fracturing and drilling flowbacks produce water having high salinity, complex components and a variety of heavy metals; secondly, a huge amount of waste fluids and oil-based mud cuttings are produced in the drilling process; thirdly, drilling circulation loss often happens in shale gas development areas where caves, cracks and underground rivers largely exist; and fourthly, constructions of the ground engineering.Besides, storage pools are apt to spill and leak by heavy rain or other factors. Therefore, when shale gas is extracted from Sichuan and Chongqing, constructions, allocation of water resources, and developing treatment technology of flowbacks must be meticulous. It is important to prevent water resources from being consumed excessively and water environment from being polluted in the developing shale gas.