方位角对页岩气钻探的影响

Influence of azimuth on shale gas drilling

为了达到增产目的,水平井技术在页岩气开发中被广泛应用,因其影响因素众多,文中结合国内外相关资料,分析了方位角对页岩气开发的影响。结果表明:沿最小水平应力方向钻井,不仅能有效降低页岩气钻井风险,而且可使储层破裂体积达到最大,从而增加产量;在完井过程中,通过增加沿水平井方向压裂间隙的长度,达到降低成本的目的。然而,在某些情况下,钻井的方位角并非沿最小应力方向,此时,安全钻井液密度窗口会下降,甚至消失。复杂裂缝提高了破裂压力,严重威胁井壁稳定性。

Horizontal drilling becomes common practice in shale gas development to maximize production and there are many factors affecting the production. Based on the related data, the influence of azimuth on shale gas development is analyzed. When the well is drilled in the direction of minimum tlorizontal stress, the drilling risk is the lowest and the production increases a lot by maximizing the fracture volume; during well completion, the costs are reduced by increasing the stage lengths laterally. However, the wells are always been drilled at an azimuth that is not in the direction of the minimum stress, the safe mud-weight window will decrease, even disappeaz, the complex fractures increase the breakdown pressure and endanger the wellbore stability.