塔河南部一间房组构造裂缝有效性分析

Analysis of structural fracture effectiveness of Yijianfang Formation in the southern of Tahe area

在裂缝网络系统中,天然裂缝的开启与闭合、人工诱导缝的产生、压裂缝的形成等都受到现今应力场的影响。为对塔河地区南部定向井的施工提供科学依据,通过岩芯观察和全井壁微电阻率成像测井对塔河南部裂缝发育特征进行研究,利用钻井诱导缝方位、偶极声波测井及井壁崩落法对塔河地区南部现今地应力方向进行探讨。结果表明:塔河地区南部裂缝以高角度构造裂缝为主体,与非构造裂缝共同构成了错综复杂的裂缝网络系统;现今应力场最大水平主应力方位为NE-SW向,优势方位为50°~55°。在现今地应力的影响下,当天然裂缝与现今应力场最大水平主应力方向一致时,裂缝开度增大,呈开启状态,有效性变好。定向井尽可能地贯穿有效裂缝,钻井优选方位为NW-SE向,研究结果可为塔河南部定向钻井提供可靠的地质依据。

In the fracture network system, the opening and closing of natural fractures, the generation of artificially induced fractures and the formation of compressive fractures are affected by the current stress field.In order to provide scientific basis for the construction of directional wells in the southern of Tahe area, the fracture development characteristics in the southern of Tahe area are examined through core observation and Formation MicroScanner Image.The current in-situ stress direction of the study area is discussed by using drilling induced fracture orientation, Dipole Shear Sonic Imager and borehole wall caving method.The results show that the fractures in the southern of Tahe area are dominated by high-angle structural fractures, which constitutes an intricate fracture network system together with non-structural fractures.The maximum horizontal principal stress orientation of the present stress field is NE-SW direction, and the optimal orientation is 50°~55°.Under the influence of the present in-situ stress, when the direction of the natural fracture and the maximum horizontal principal stress of the present stress field are the same, the opening of the natural fracture increases, and the fracture is in the open state, and the effectiveness becomes stronger.The construction of directional wells should penetrate effective fractures as much as possible, that is, the preferred drilling orientation is NW-SE.The research results can provide a reliable geological basis for directional drilling in the southern of Tahe area.