西峰油田DZ—ZY地区长8储集层长石溶蚀特征及溶蚀强度计算  

Characteristics and Intensity Calculation of Feldspar Dissolution in Chang-8 Reservoir of District DZ-ZY, Xifeng Oilfield

作　　者：刘翰林[1] 王凤琴[1] 杨友运[1] 南祥 杨烁[3] 曹学刚[1] 

机构地区：[1]西安石油大学地球科学与工程学院,西安710065 [2]中国石油长庆油田分公司勘探开发研究院,西安710004 [3]中国石油大学地球科学学院,北京102249

出　　处：《新疆石油地质》2017年第1期27-33,共7页Xinjiang Petroleum Geology

基　　金：国家油气重大专项(2011ZX05044);国家自然科学基金(41102083)

摘　　要：长石溶蚀作用是鄂尔多斯盆地西峰油田DZ—ZY地区长8储集层次生孔隙发育的主控因素。为了分析研究区长8储集层长石溶蚀特征,综合利用铸体薄片、扫描电镜、电子探针等分析技术,同时基于长石非全等溶解的性质,通过对各长石溶蚀理论次生孔隙度和溶解率的计算,准确划分长石溶蚀强度:弱溶蚀(溶解率小于25%)、中溶蚀(溶解率25%~50%)、强溶蚀(溶解率50%~75%)和极强溶蚀(溶解率大于75%)。研究表明:长石溶蚀现象在研究区普遍存在,长石溶孔对储集空间贡献率高达60%.但不同长石类型溶蚀程度存在明显差异,其中,钾长石溶蚀程度高于斜长石,且钾长石溶孔比例最大。研究区长石溶蚀强度以中溶蚀(约占40%)和强溶蚀(约占36%)为主;钾长石溶蚀贡献率随溶解率的增加而增加,斜长石则相反,即钾长石溶孔率将会直接影响长石溶蚀强度,而斜长石溶孔对孔隙度的贡献较小,尤其是在溶蚀强度较高的情况下。Feldspar dissolution is the main controlling factor of secondary pores in Chang-8 reservoir of District DZ-ZY, Xifeng oilfield.This study uses the thin section, scanning electron microscopy（SEM）, electron microprobe（EMPA） and other analytical techniques to ana-lyze the characteristics of feldspar dissolution. Meanwhile, based on the properties of incongruent dissolution and theoretical calculations ofsecondary porosity and dissolution rate of feldspar, 4 kinds of feldspar dissolution intensity are determined： weak dissolution（dissolutionrate 25%）, medium dissolution（dissolution rate of 25%~50%）, strong dissolution（dissolution rate of 50%~75%） and extremely strong dis-solution（dissolution rate 75%）. Feldspar dissolution commonly occurs in the study area and the contribution of feldspar dissolution poresto reservoir spaces reaches 60%. But there are significant differences among the dissolution degrees of different feldspar. The degree of dis-solution of potassium feldspar is higher than that of plagioclase, and the dissolution pores of potassium feldspar accounts for the largest pro-portion. The dissolution of feldspar in the study area is dominated by medium dissolution（about 40%） and strong dissolution（about 36%）.The contribution rate of potassium feldspar dissolution increases along with the dissolution rate and that of plagioclase is the opposite espe-cially under the conditions of relatively high dissolution intensity.

关 键 词：鄂尔多斯盆地 上三叠统 延长组 西峰油田 次生孔隙 长石溶蚀 溶蚀特征 定量计算 

分 类 号：TE112.23[石油与天然气工程—油气勘探]