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渤中凹陷古近系沙河街组砂岩具有粒度细(粉砂)、成岩演化程度高、埋藏深(大于3 000m)、物性差的特征,是否发育相对高孔渗储层是制约该地区深层油气勘探的关键问题。根据渤中凹陷QHD35-2-1井的测井、取心及测试资料,研究了深层砂岩的成岩机制和高孔渗储层的成因,结果表明:渤中凹陷深层古近系沙河街组砂岩处于中成岩期—晚成岩期,砂岩粒度细,咸水低温钙质沉淀胶结,这些因素对深部储层孔渗的发育与保存不利;高温及高异常压力的存在,使得粉砂岩储层中矿物成分大量溶蚀,形成了受异常压力保护的原生粒间孔隙,以及长石、碳酸盐岩胶结物与岩屑等溶蚀形成的次生孔隙,从而构成了深埋条件下的相对高孔渗储层。
The sandstones of the Shahejie Formation of the Paleogene in the Bozhong Sag have the characteristics of fine grain size (silt), high degree of diagenetic evolution, deep burial (greater than 3,000 m) and poor physical properties. Whether the relatively high porosity and permeability reservoirs are developed is the key factor restricting the deep oil and gas The key issue of exploration. According to logging, coring and testing data of QHD35-2-1 well in Bozhong Sag, the diagenesis mechanism of deep sandstone and the genesis of high porosity and permeability reservoir are studied. The results show that the sandstone of Shahejie Formation in the deep Paleogene of Bozhong Sag In the mid-diagenetic-late diagenetic stage, the fine sandstone is fine-grained and the low-temperature calcareous sedimentation and cementation of salt water are unfavorable for the development and preservation of the porosity and permeability of the deep reservoirs. The existence of high temperature and high abnormal pressure makes the mineral A large number of dissolution of the composition, forming the primary intergranular pores protected by abnormal pressure, and the secondary pores formed by the dissolution of feldspar, carbonate cements and cuttings, thus forming the relatively high porosity reservoir under deep burial conditions Floor.