肯基亚克盐下油田水力破裂缝成因及分布预测

Genesis and distribution prediction of hydraulic fractures in Kenkiyak Oilfield

目前,水力破裂缝研究仅限于岩心尺度的描述,难以产生矿场应用效果。通过对肯基亚克盐下油田研究认为:大量外排的压实流体和源岩大量生排烃为水力破裂缝发育提供了丰富的流体来源;快速沉降、强烈成岩、盐丘刺穿及良好的封闭环境、优越的生烃条件促使了异常孔隙流体高压的形成,为水力破裂缝发育提供了重要条件;而孔隙流体压力大于地层破裂压力则是水力破裂缝发育的力学机制。因此,研究区水力破裂缝普遍发育。实验表明,闭合状态的水力破裂缝渗流能力仍高于基质。根据现今应力场模拟和水力破裂缝开启条件分析认为,研究区当前水力破裂缝基本处于闭合状态,但对油田生产仍起到重要的积极作用。通过岩心描述,开启先前闭合裂缝模式是研究区水力破裂缝的主要形式。最后,分析水力破裂缝测井响应特征,依据岩心刻度测井法,确定高渗优质储层邻近的低渗层是水力破裂缝发育集中区。

At present, the study of hydraulic fracture is limited to the description of core size. It is difficult to produce an effect of field application. Through the study of Kenkiyak Oilfield, it is believed that a great number of outer-drainage compaction fluid and a great quantity of hydrocarbon generation and hydrocarbon expulsion of source rocks provide a rich fluid source for development of hydraulic fracture; that rapid subsidence, strong diagenesis, salt dome piercement, closed-well environment and excellent hydrocarbon generation conditions prompt the formation of abnormal pore fluid pressure, which provides the important conditions for the development of hydraulic fracture. That the pore fluid pressure is greater than the fractured pressure of formation is the mechanics mechanism of hydraulic fracture development. So, large amounts of hydraulic fractures developed in the study area. The experimental results show that the seepage capacity of hydraulic fracture at closed state is higher than the matrix. According to the current stress field simulation and the analysis of the open condition of hydraulic fi＇acture, the hydraulic fractures are closed in study area at present, but they still play an important role in oilfield production. Opening pattern of previous closed fracture is the main pattern of hydraulic fracture in the area in terms of core description. Finally, based on core calibration logging method, it is determined that the low permeability reservoirs adjacent to high permeability reservoir are the concentration area of hydraulic fracture development through the analysis of logging response feature of hydraulic fracture.