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综合运用测录井、试油和实验分析测试资料及盆地模拟方法,在霸县凹陷古近系中深层今地层压力分析的基础上,恢复了古地层压力的演化过程,探讨了古地层压力对储层成岩作用的影响。分析结果表明,古近系中深层地层压力存在超压原始积累—超压降低2个阶段,其演化表现出“低—高—低”变化特征。沉积初期地层压力以常压为主,在距今约40 Ma开始发育超压,约25~20 Ma期间超压达到最高值,表现为强超压,随后地层压力持续降低,至今演化为常压、弱超压,局部地区发育中超压。早期快速埋藏导致的欠压实作用是地层超压形成的主要原因,而后期生烃增压作用不明显。古地层超压抑制了储层的成岩作用,具体表现为:1抑制压实作用的进行,从而保护储层的原生孔隙;2抑制黏土矿物的转化,减少Ca2+等的来源,从而减弱胶结作用发生,保护储层的孔隙;3抑制有机酸的生成,阻碍流体渗流与物质交换,从而不利于长石溶蚀作用的发生。
Based on the analysis of the present and middle layer pressure in the Paleogene in Paxian sag, the evolutionary process of palaeostress pressure is comprehensively studied by using the logging data, oil testing data and experimental data and the basin simulation method. The paleo-formation pressure Influence of reservoir diagenesis. The analysis results show that the overpressure of the Paleogene strata is mainly composed of overpressure accumulation and overpressure reduction. Its evolution shows a “low - high - low” variation. During the initial depositional period, the formation pressure was dominated by atmospheric pressure, overpressure began to develop at about 40 Ma, and overpressure reached the highest value during about 25-20 Ma, indicating strong overpressure. Subsequently, the formation pressure continued to decrease and has evolved to atmospheric pressure , Weak overpressure, overpressure during development in some areas. The under-compaction caused by early rapid burial is the main cause of strata overpressure formation, but the effect of hydrocarbon generation and pressurization in later stage is not obvious. The overpressure of the Paleogene suppresses the diagenesis of reservoirs, which is manifested as follows: 1 Suppressing the compaction and thus protecting the primary porosity of the reservoir; 2 Inhibiting the conversion of clay minerals, reducing the source of Ca2 + and the like, thereby reducing the occurrence of cementation , To protect the pores of reservoirs; 3 to inhibit the formation of organic acids, hinder the fluid seepage and material exchange, which is not conducive to the occurrence of feldspar erosion.