松辽盆地古龙凹陷构造应力场弹-塑性增量法数值模拟

泥岩裂缝油气藏是大庆油田古龙凹陷主要的油气藏类型之一 ,构造裂缝储层在该类油气藏中占有重要地位。老第三纪末及现今的应力释放区是该区泥岩裂缝性储层的主要发育区。构造应力释放区的泥岩储层渗透条件得到改善 ,现今应力场控制着地层压力的分布。采用弹塑性增量的有限元法模拟了古龙地区青山口组地层老第三纪末与现今两期构造应力场。根据区域构造研究结果确定主应力方向 ,以确定应力场的分期。采用晶格位错密度法、水压致裂法及声发射法测定岩石的构造应力值 ,并作为构造应力场模拟的约束条件。由岩石力学试验测定岩石物性参数 (弹性模量和泊松比 ) ,根据区域沉积相带分析建立岩相地质模型。结合钻井及区域地质资料 ,对模拟结果进行分析研究 ,识别出古今四个应力释放区。其中他拉哈、新站两应力释放区的勘探程度高 ,绝大多数钻井资料印证了数值模拟结果的正确性 ;而葡西、杏西高西两应力释放区钻井资料较少 ,应作为潜在的裂缝储层勘探靶区。

NUMERICAL SIMULATION OF TECTONIC STRESS FIELD IN GULONG DEPRESSION IN SONGLIAO BASIN USING ELASTIC-PLASTIC INCREMENT METHOD

The oil and gas reservoir deposited in shale fractures is a major type in Gulong depression, Daqing oil field. The shale fractural reservoirs develop mainly in the stress released regions at the end of Paleogene and present. The permeable condition of shale reservoirs with stress releasing has been improved, and the current stress field controls the stress distribution of strata. In this paper, the tectonic stress fields in Gulong depression are simulated by using the elastic|plastic increment method. Firstly, the tectonic stress fields are classified into two main stages. The tectonic stress orientations are configured according to the regional geological studies. The geological models, with different lithological phases are established in the light of the regional sedimentary studies. The methods for testing core stress were used including dislocation density (on TEM), hydraulic fracturing and acoustic emission methods, and the test results were treated as simulation constrains. Four stress releasing regions have been identified from the simulated results combined with drilling data and geological information in the area. Among the four regions, most of the drilling data confirmed the simulated results in Talaha and Xinzhan areas that have been highly explored, and there are not many drilling data in Xingxi|Gaoxi and Puxi areas that should be the potential areas in the future exploration.