页岩气藏缝网形成影响机理研究

页岩气开发对我国能源保障具有重要的现实意义,页岩气开发的关键在于通过体积压裂形成复杂裂缝网络,从而提高页岩气的流通能力。国内对缝网形成机理研究较少,在文献调研基础上,系统分析了缝网形成影响机理:建立了岩石脆性判断准则,得出脆性指数大于40,储层适合体积压裂;分析了天然裂缝、地应力和诱导应力对缝网的影响,得出诱导应力有利于缝网形成,确定了天然裂缝张开后的走向及力学条件;建立了转向半径计算模型,得出泊松比和水平主应力差大于临界值时,难于形成缝网。研究结果为页岩储层体积压裂、判断缝网形成提供了参考和借鉴作用。

Mechanism of Creating Network in Shale Reservoir

Shale gas development have a great effect on Chinese energy security, the key to shale gas development is the creation of complex fracture networks. Home experts insufficient understand the formation mechanism of network fracture. In this paper, the factors of creation of network fracture are systematically analyzed based on literature research, rock brittleness criterion is established; the reservoir is suitable to volume fracturing when brittleness index is greater than 40. Through analysis of effect of natural fracture, fracture induced stress and stress difference on network, Induced stress is useful to form network, the mechanics of natural fractures having been open is established, computational model of turning radius has been established. It provided a reference to determine whether network can be developed.