高温高压储层安全钻井液密度窗口确定技术

MUD DENSITY DETERMINATION OF HT/HP RESERVOIR FORMATION

蔚宝华 王炳印 曲从锋 孟艳山 邓金根

Yu BaoHua Wang Bingyin Qu CongFeng Meng YanShan Deng Jingen

中国石油大学石油天然气工程学院, 北京 102249

Petroleum and Gas Engineering Faculty, China Petroleum of University, Beijing 102249

井壁温度变化和井壁渗流对高温高压储层安全钻井液密度窗口的影响不容忽视,而确定钻井时安全钻井液密度窗口的常规方法中没有考虑井壁温度变化及井壁渗流的影响,为安全钻井带来了隐患。为此,依据孔隙热弹性小变形应力叠加原理,从附加温变应力场以及附加渗流应力场作用下井周应力场计算出发,结合地层的强度准则,建立了综合考虑井壁温度变化及井壁渗流情况下高温高压储层坍塌压力、破裂压力的计算模型,并分析了井壁温度变化及井壁渗流对安全钻井液密度窗口的影响规律。为高温高压储层安全钻井液密度窗口的设计提供了依据。

Suitable drilling fluid density is the primary factor for drilling through HT/HP reservoir formation safely and rapidly. But in conventional methods for determining fracturing pressure and caving pressure, the influence of borehole temperature change and drilling fluid penetration is neglected, which would bring in hidden trouble for safe drilling. Thus, according to porothermoelasticity principles, stresses distribution around borehole are determined combined with stresses duo to formation temperature change and drilling fluid seepage. Following formation failure criterion, fracturing and caving pressure calculation mode are deduced when drilling HT/HP reservoir formation, and the influences of temperature change and borehole seepage on safe mud window are analyzed, all of these would be useful for safe drilling fluid density design, when drilling in HT/HP reservoir formation.

10.3969/j.issn.1000-7393.2005.03.012