四川震旦系灯影组天然气藏储渗体的再认识

通过对四川资阳、威远地区震旦系灯影组11口井岩心分析,结合地面剖面研究后认为,震旦系末的桐湾运动引起的地表和近地表古岩溶所形成的地表风化残积砾屑白云岩、近地表50m左右地层内的岩溶洞、岩溶漏斗、岩溶管、漏滴状小溶洞及溶洞崩塌角砾岩的角砾间几乎全被来自风化面下渗的沉积物、渗流粉砂及胶结物充填满,现存的22种孔、洞、缝中最主要的储集空间有:①重结晶白云岩的晶间孔、洞;②沿40°左右裂缝扩溶的成排、成串溶洞,经白云石半充填后的残余洞;③沿构造裂缝溶解,经多种形式,若于世代白云石成花边状胶结后的残余孔、洞;④70°～80°方向的张裂隙。它们发生的初始时期可能分别为海西期、印支期、晚加里东期和喜山期。

FURTHER UNDERSTANDINGS OF THE GAS-RESERVOIR ROCKS OF SINIAN DENGYING FORMATION IN SICHUAN,CHINA

After studying cores of Dengying formation from 11 wells in Ziyang and Weiyuan areas in Sichuan,China,together with analyzing profiles,the authors believed that sediments and spars from erosional surface had filled pores in the surface weathered residual dolorudites,and the 50m near surface karstic vugs,tubes,small drop-like karstic vugs,and avalanche breccia which had been formed during the Tongwan tectonic movement. Following are main types of fluid accumulating spaces among the existing 22 kinds of pores,vugs,and fissures. 1. Inter-crystal pores in recrystallized dolomites formed at Hercynian age,secondary pores and vugs formed by dissolution in pore-water with organic acid and COZ decomposed from organic matter,and residual pores and small vugs partly filled by dolospars; 2. Rows of karstic vugs formed at Indosinain age along micro-cracks of about 40°,and residual vugs partly filled by rhombic dolomites; 3. Residual vugs after cementation of multi-form and multi-generation folo-spars at Caledonian age,which were first formed through dissolution by underground water along tectonic cracks;4. Tension fissures about 70°～80° formed at Himalayan age.