Evolution Of Sedimentary System And Source-Reservoir-Caprock Association In Tertiary Of Pearl River Mouth Basin

Since the 1980s,large-scale oil and gas exploration in the Pearl River Mouth Basin,and the total oil and gas resource quantity can be 80.94x108t oil equivalent.At present,oil and gas exploration degree of shallow shelf area is high,but the probe is little in the field of deep exploration and deep water area of the South Slope.The problem is the lack of a comprehensive study of the basin as a unit,and there is less research in the basin-level distribution and evolution of depositional systems.Therefore,the deposition system of the entire basin was studied systematically in this thesis to open up new prospects for oil and gas exploration of Pearl River Mouth Basin.Under the guidance of the seismic sequence stratigraphy and sedimentology theory,based on the core observation and description as well as comprehensive analysis of seismic and logging data,taking tectonic dynamic,sedimentary provenance system,the sedimentary types and distribution characteristics of sedimentary facies as the main line;the sedimentary evolution in Tertiary as the core,following the research idea of multi-point expansion,from point to line and from line to plane,adopting the research methods of the combination of structure and sedimentary facies and the integration of geology logging and seismic combination,the type and distribution of the sedimentary formation are focused on,the sedimentary evolution law is cleared up,the responsive relationship between reservoir combination and the evolution of depositional system is explored,advantageous source-reservoir-caprock association is delineated,the problem that the recognition on geological rule of oil and gas isn't deepgoing has been solved.Main conclusions were listed as follows:1.In terms of basin structure characteristics:2 categories(rift and depression)and 4 kinds of basin structure are identified in the pearl river mouth basin.Rift is comprised of half graben(simple,shovel,gentle slope fault terrace type)and graben(stepped),and depression is mainly asymmetric.The sag is overall a single fault dustpan-like depression with typical distribution characteristics of being lower and deeper and in the north than the south.2.In the aspect of provenance system:through the restoration of ancient landscape and the analysis of seismic reflection structure,the provenance systems in different period were determined.In the faulting period,there isn't a unified source supply,mainly from the faulted surrounding uplift;in the fault-depressed diversionary period,the Pearl River water system has begun to provide provenance in the line of Huizhou-Xijiang-Baiyun,besides the faulted surrounding uplift;in the depression period,deposition source tended to unity and suppled the whole basin through the Pearl River water with terrigenous denudation products from Southern part of China.3.In the sedimentary system e'volution and source-reservoir-cap aspects:The general sedimentary evolution was a gradual evolution rule of transgression,enhancement of the transgression made the sedimentary facies changing from continental facies,marine-continental transitional facies to marine facies.Correspondingly,source-reservoir-caprock association is divided into three different types,i.e.continental source-continental reservoir-continental caprock,continental source-marine reservoir-marine caprock and marine source-marine reservoir-marine caprock ones.Continental source-continental reservoir-continental caprock is mainly distributed in the north part of the basin;continental source-marine reservoir-marine caprock is widely developed in the basin;marine source-marine reservoir-marine caprock is distributed in the deep water area of ZHU? depression.