海拉尔油田不同区块地应力分布规律

Distribution Rules of Ground Stress in Different Blocks in Hailaer Oilfield

海拉尔油田兴安岭群含凝灰质沉积岩及布达特群浅变质岩均属于低孔特低渗储集层,储集层物性差,自然产能低,压裂后油井增加的产能与压裂的效果密切相关。认识储集层的地应力特征,有助于压裂设计时确定裂缝的产状、缝长和缝宽等参数,提高压裂效果。综合分析了已有的地应力计算模型,采用考虑构造应力和热应力影响的地应力计算模式,利用海拉尔油田实际测井资料,分贝28、贝16及苏131三个区块进行地应力综合解释,计算出沿深度连续的地应力剖面数据、岩石力学参数等,给出了海拉尔油田不同区块适用的地应力计算数学模型,得出了分区块的纵向和平面地应力分布规律。兴安岭群沉积岩储集层地应力水平较低,在不同深度上表现出较好的线性分布特征;布达特群浅变质岩储集层地应力差值较大,线性规律性不明显。应用波速各向异性、粘滞剩磁法、井筒崩落法和热应变恢复法,确定了海拉尔油田水平最大主应力方向为99～107°,水平最小主应力为9～17°.

The Xing＇anling group＇s tuffaceous sedimentary rock and the Budate group＇s epimetamorphic rock in Hailaer oilfield belong to low porosity and extra-low permeability reservoir, being characterized by poor physical property, low natural productivity and sensitive hydraulic fracturing effectiveness. A thorough understanding of the current ground stress of the reservoirs can help to determine such parameters as occurrence, length and width of fractures in fracturing design, reducing bhndness of hydraulic fracturing operation. Analysis of the existed stress calculation model considering both tectonic stress and thermal stress is made in combination with real well logging data from this oilfield, and the ground stress interpretations of Bei-28, Bei-16 and Su-131 blocks are given, obtaining the stress profiles and the lithomechanics parameters along depth, and mathematical models for stress calculations in different blocks. The calculated vertical and plane stress distribution rules indicate that Xing＇anling group＇s sedimentary reservoir is in lower ground stress and preferable linear distribution feature in different depths, while Budate group＇s epimetamorphic reservoir appears in big difference of stress, with unclean the linear distribution rule. Applying wave velocity＇s anisotropy, viscous remanence method, the weUbore caving method and thermal strain recovery method, it is determined that the maximal plane major stress direction ranges from 99° to 107° and the minimal plane major stress direction is from 9°and 17°.