超临界CO_2开发页岩气技术

Feasibility Analysis on Shale Gas Exploitation with Supercritical CO_2

页岩气藏具有低孔隙压力、低孔隙度、低渗透率和高含黏土等特点,开发难度较大。为了降低页岩气藏开发成本,提高页岩气经济技术可采储量,需要一种新的高效页岩气开发技术。通过分析页岩气成藏、页岩储层、页岩气和超临界CO2流体的特性,结合超临界CO2喷射破岩试验结果和CO2、CH4与岩层吸附特性可知:超临界CO2喷射钻井能够在页岩层中获得较高的机械钻速,同时不会使页岩层产生黏土膨胀、水锁等效应;利用超临界CO2流体进行储层压裂改造,能使储层产生更多微小裂缝,有助于页岩气生产,最重要的是CO2与页岩的吸附强度高于CH4,CO2能置换吸附在页岩上的CH4,在提高产量和生产速率的同时,实现CO2永久埋存。因此,超临界CO2开发页岩气无论从技术上和经济上均具有较大优势,将成为未来页岩气高效开发的新技术。

Shale gas reservoir has the characteristics of low pore pressure, low porosity, low permeability and high content of clay, so it is difficult to exploit. In order to decrease the development cost and increase the technical and economic recoverable reserves,a new and efficient technology is needed. The characteristics of shale gas reservoir,shale gas, reservoir formation and supercritical CO2 are analyzed,the adsorption properties of CO2 ,CH4 with shale and rock broken result with supercritical CO2 jet are also analyzed, and some conclusions have been gotten from the above analysis. It can obtain higher penetration rate in the shale formation with supercritical CO2 jet,and the clay swelling and water lock effect will not occur, many micro-fractures would be form in the formation when the supercritical CO2 is used to fracture, which of them is helpful to shale gas production; the most important is the CO2 molecule has stronger adsorption ability with shale than that of CH4 molecule,it can replace the CH4 adsorbed on organic matter and tiny particles of clay mineral surface,then increase the output and production rate,at the same time the CO2 is buried for ever. So shale gas exploitation with supereritical CO2 has many advantages on technical and economic ,believed that it can be the new and efficient technology in shale gas exploitation.