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在野外露头、岩心观察、薄片鉴定以及扫描电镜等资料研究的基础上,对普光气田飞仙关组溶蚀作用进行了研究,认为飞仙关组至少经历了3期溶蚀作用的改造,即早期大气淡水溶蚀作用、液态烃期溶蚀作用和与TSR有关的气态烃期溶蚀作用。前两期溶蚀作用由于形成时间较早,多被后期充填,但对后期溶蚀作用的发生鉴定了基础。气态烃期溶蚀作用是普光现今储层形成的关键,形成的次生孔隙无沥青充填或沥青充填在孔隙的中央。此外,在前人研究的基础上对气态烃期溶蚀作用的机理进行了探讨,认为溶蚀作用的发生是由于对碳酸盐饱和的高含H2S的地层水和对碳酸盐饱和的不含H2S的地层水混合形成对碳酸盐不饱和的新的浓度的地层水,这种地层水打破了原来的平衡状态,从而对碳酸盐岩产生了强烈的溶蚀。其中含H2S的地层水来自于硫酸盐热化学反应生成的H2S的溶解;不含H2S的地层水既有来自烃源岩的压实水,又有来自硫酸盐热化学还原反应生成的淡水,是这两种水共同参与的结果,并建立起相应的溶蚀作用模式。
Based on the study of outcrops, core observation, sheet identification and scanning electron microscopy, the dissolution of Feixianguan formation in Puguang gas field was studied. It is considered that the Feixianguan formation at least experienced the alteration of three stages of dissolution, that is, the early atmosphere Freshwater dissolution, liquid hydrocarbon dissolution and TSR-related hydrocarbon phase dissolution. The dissolution of the first two periods was mostly filled later because of the formation time, but the foundation of the later dissolution was identified. Gas hydrocarbon phase dissolution is the key to the formation of Puguang reservoirs. The formation of secondary pores filled with asphalt or asphalt filled the center of the pores. In addition, on the basis of previous studies, the mechanism of gas phase hydrocarbon erosion is discussed. It is considered that the dissolution occurs due to the saturation of carbonate-rich formation water with H2S and carbonate-saturated H2S Of the formation water to form a new concentration of unsaturated carbonate water, the formation of water to break the original equilibrium, resulting in a strong carbonate carbonate erosion. The formation water containing H2S comes from the dissolution of H2S formed by thermal chemical reaction of sulfate. The formation water without H2S contains both compacted water from source rocks and fresh water from the thermochemical reduction reaction of sulfates. The results of these two kinds of water participate together and establish the corresponding modes of dissolution.