川东上二叠统生物礁成岩作用与孔隙演化

川东地区上二叠统长兴组生物礁礁体经历了海底、潮坪、陆上、浅-中埋藏和深埋藏成岩环境,而礁间相和非礁相沉积直接从海底成岩环境进入浅-中和深埋藏成岩环境。礁灰岩中的大量原生孔隙被海底和埋藏成岩环境中多期胶结物充填而丧失殆尽。礁间生物屑灰泥沉积物微孔隙在压实过程中逐渐消失。礁体的白云岩主体是埋藏成岩环境中形成的,一般孔、渗性良好。礁顶发育2—7m厚的潮坪白云岩,则孔、渗性很差。

DIAGENESIS AND PORE EVOLUTION OF UPPER PERMIAN REEFS, EASTERN SICHUAN PROVINCE

During the period of Late Permian, transgression from east to west occurred in Sichuan and its adjacent areas. The Upper Permian Changxing Formation reefs in East Sichuan were pinnacle and patch reefs which climbed on carbonate ramp with tragression. The Changxing reefs underwent five diagenetic environments, i. e. the sea floor,reef ialand tidal flat, subaerial, shallow to moderate burial and deep burial diagenetic environments. However, interreefs and non-reefS had never exposed and undergone meteoric diagenesis. They underwent from sea floor to shallow-moderate burial and deep burial diagenetjc environments. A lot of primary pores of reef rocks (shelter and growth framework voids, intrabiotic pores, interbreccia cavities, etc.) were almost filled by multi-phase cements of sea floor and burial diagenesis. Interreef biogenic debris and lime mud deposits had many micropores that were progressively vanished during burial compression process.Most of the dolomites of a reef body were formed by the replacement of compaction fluids which converged towards and through reefs in burial diagenetic environmemt and have good porosity and permeability. The main reservoir spaces are late solution pores and intercrystalline pores.