川西北异常高压区须家河组砂岩孔隙演化特征

Evolutionary Characteristics of Pores in Xujiahe Formation Sandstones of Upper Triassic at the Areas with Abnormally High Pressure in North West Sichuan

本文研究了砂岩成岩作用和有机质热演化历史,探讨了川西北异常高压区上三叠统须家河组砂岩储集层孔隙演化的特征,指出次生孔隙的主要发育时期在J_2中期—J_3中期,并结合天然气性质和油气生成、运移规律阐明了砂岩储集层的致密性和非均质性以及异常高压的形成、保存条件,提出今后勘探该区应注意寻找裂缝和次生孔隙发育的地层圈闭油气藏。

Based on researching the diageneses of the sandstones, through studying the thermal evolution of the organic matters, this paper discusses the evolutionary characteristics of the pores in geological history times in Xujiahe. Formation sandstone reservoirs of Upper Triassic at these areas with abnormally high pressures in north west Sichuan, and points out that the mainly developing times of the secondary pores were during the medium-terms of Middle Jurassic and Late Jurassic. Combining with the properties of natural gas and the rules of the generation and migration of oil and gas,the author expounds the compactness and heterogeneity of the sandstone reservoirs and the conditions of the formation and reservation of abnormally high pressure. It is proposed that the oil and gas reservoirs of stratigraphic traps in which the fractures and secondary pores are developed must be paid attention to when exploring these areas in the future.