济阳坳陷及其南缘奥陶系碳酸盐岩潜山储集性及控制因素

The main research area of this thesis is Jiyang Depression in the Bohaiwan Basin and its southern margin. The object formation is Ordovician carbonate. The research is based on the outcrop observation and measurement of Ordovician carbonate and the drilling data of the oilfield. The internal reservoir characteristics of carbonate buried hill and its distribution were studied by comprehensive methods of sedimentology, reservoir geology and structural geology and technics of cathodoluminescence(CL)3electron microprobe,casting and C O isotope analysis etc. The influence depth of paleokarst facies formed during the Paleozoic is discriminated as 36-84m. The sollution porosity is well developed in paleokarst facies of Ordovician carbonate and is an important type of internal reservoir of buried hill. It may be infered that the fractures may be formed mainly during the Mesozoic and Cenozoic, they were not developed during the early Paleozoic when only micro-fractures might be created. The carbon and oxigen isotope analysis shows that the calcite cements in the fractures of Ordovician carbonate and secondary solution pores were related with meteoric water and three stages of fractures were divided. The reservoir space of Ordovician carbonate are mainly secondary porosity, cavern and fracture. The development of structural fracture was controlled by the lithology and tectonic background. More fractures exist in dolomite than that in limestone. There are also more fractures near the fault and the axis of fold. The development of porous reservoir is mainly controlled by the lithology and diagenesis, especially dolomitization and dissolution. It also results in the heterogeneity vertically. So the lithology is the basic factor for the forming of internal reservoir of buried hill and the tectogenesis and diagenesis are key factors to improve it. The porosity in carbonate might experienced solution-cementation-resolution or recementation. The porosity evolution history was a kind of historical dynamic equilibrium. The internal reservoir of Ordovician carbonate is the comprehensive result of constructive and/or destructive diagenesis. The worm's eye maps of the early Paleozoic and middle-upper Proterozoic were plotted. It was inferred that the paleostress field evoluted from NNW to NW during the Mesozoic and Cenozoic. Three types of buried hills can be divided: C-P/Pzi, Mz/ Pzi and E/ Pzi. The unconformity of the buried hill of E/ Pzi type, comparatively, was formed and reconstructed latestly, t he p orous r eservoir c ould b e w ell p reseved. T his c ondition w as v ery favorable t o t he migration and accumulation of oil and gas and could form upstanding association of source-reservoir-cap rocks. The buried hills of Mz/ Pzi and C-P/Pz] type were took second place.