东濮凹陷次生孔隙成因探讨

Cause of secondary pores in Dongpu Depression

东濮凹陷深层勘探预示着在深层发育异常高孔隙储层。利用实际资料,发现异常高压纵、横向分布特点,从宏观和微观2个方面对其成因和对储层的作用进行分析。结果显示:超压异常的形成与不均衡压实、孔隙流体增加、孔隙体积减小有关。超压异常控制成岩作用环境及孔隙的纵向演化,主要表现在高次生孔隙的发育和孔隙的分带性。次生孔隙的发育主要受微裂缝形成、生烃酸性环境溶蚀作用、原生孔隙的保存作用、热液循环溶蚀作用和热液交代作用的影响。在异常超压控制下,东濮凹陷深层形成了以次生孔隙发育带为主、次生孔隙递减带和致密带为辅的次生孔隙分布格局。次生孔隙带的广泛发育,对于扩大东濮凹陷深层勘探领域有重要意义。

The deep exploration indicates that there are deep-seated reservoirs with extra high porosity in Dongpu Depression. Distribution characteristics of abnormal pressure are made clear both vertically and laterally by using field data. The mechanism of abnormal pressure and its functions to reservoir were analyzed on macroscopic and microscopic aspects. The result indicates that the mechanism of abnormal pressure is related to disequilibrium compaction, increase of fluid volume and decrease of pores. Overpressure controls the diagenesis environment and vertical evolution of pores, which is mainly displayed in highly developed secondary pores and zoning of pores. The development of secondary pores is mainly affected by microfissure, corrosion in acid environment of hydrocarbon generation, preservation of primary pores, corrosion of thermal fluid cycling and hydrothermal metasomatosis. Under the control of overpressure, secondary pores distribution pattern of mainly development zone and secondarily decreasing and tight interval has been formed in Dongpu Depression. The widely developed secondary pore zones have great importance in expanding the deep exploration areas in Dongpu Depression.