玛北油田XIA72井断块百口泉组钙质砂砾岩成因

玛北油田MA131井区XIA72井断块下三叠统百口泉组油层段多井钻遇钙质砂砾岩,气测全烃含量低,储集层物性和含油性差,影响了水平井油层钻遇率和后期水平井部署。根据岩心、测井、地震等资料,对XIA72井断块百口泉组钙质砂砾岩的成因、识别方法及分布规律进行了研究。结果表明,研究区钙质砂砾岩的钙质胶结物形成于成岩晚期,钙质胶结物对储集层具有破坏作用,钙质砂砾岩的分布主要受沉积相和早期断层控制,具有高电阻率、高密度和低声波时差的测井响应特征,地震剖面上表现为“亮点”反射特征。采用最大似然体、均方根振幅及最大振幅,对研究区钙质砂砾岩分布进行了预测,其中,最大振幅能够精确反映其展布特征。研究区钙质砂砾岩表现为受沉积微相控制的团块状和断层控制的南北向条带状分布特征,根据此预测结果,对27口水平井的部署进行优化。

Genesis of Calcareous Sandy Conglomerate of Baikouquan Formation in Well XIA72 Fault Block,Mabei Oilfield

Calcareous sandy conglomerate was encountered in multiple wells in the oil layers of the Lower Triassic Baikouquan formation in Well XIA72 fault block, MA131 well block, Mabei oilfield, gas logging result shows that the total hydrocarbon content is low, and the physical and oil-bearing properties of reservoirs are poor, which affects the oil layer drilling rate and the later horizontal well deployment. According to the core, logging and seismic data, the genesis, identification and distribution of calcareous sandy conglomerate in the Baikouquan formation, Well XIA72 fault block were discussed. The results show that the calcareous cement in the calcareous sandy conglomerate in the study area was formed in the late diagenetic stage, and it has a destructive effect on the reservoir. The distribution of the calcareous sandy conglomerate is mainly controlled by sedimentary facies and early faults, with the logging responses characterized by high resistivity, high density and low interval transit time, which are reflected as “bright spots” on the seismic section. The distribution of the calcareous sandy conglomerate in the study area was predicted by means of the maximum likelihood system, root mean square amplitude and maximum amplitude, among which the last one can accurately reflect the distribution. The calcareous sandy conglomerate in the study area is found in massive distribution controlled by sedimentary microfacies and NW trending banded distribution controlled by faults. According to the prediction results, the deployment of 27 horizontal wells was optimized.