The Research Of Hydrocarbon Accumulation Conditions Of Buried Hills In Liaoxi Low Uplift

Liaoxi Low Uplift has nice exploring prospect in Bohai Bay Seas,but the present fundamental study work about the petroleum geology is relatively lagging or not systematic enough.Thus,taking the buried hills in Liaoxi Low Uplift as the main research object,and according to theories of such disciplines as Petroleum Geology,Tectonic Geology,Petroleum Geochemistry,and so on,and in the basis of predecessors' researches,and by making full use of geological,geophysical,geochemical data,and so forth,the buried hills' hydrocarbon conditions such as hydrocarbon conditions,reservoir conditions,seal ability and some other elements are studied,further coupled with the dissection of buried hills hydrocarbon reservoirs,the hydrocarbon accumulation main controlling factors and modes are summed up.The third section of Shahejie formation hydrocarbon source rock in Liaoxi Sag and Liaozhong Sag is the main source for the buried hills hydrocarbon reservoir in Liaoxi Low Uplift,it's huge in thickness,and rich in organic matter,and well on organic type,and high in organic maturity.Besides,the first section hydrocarbon source rock has some contribution too,thus the oil and gas in buried hills hydrocarbon reservoirs is with the characteristics that most hydrocarbon are compound source and minority are single source.There develops three layers of strata and three kinds of reservoirs in Liaoxi Low Uplift buried hills,which are igneous rocks,carbonatite rocks and metamorphic rocks.Under the control of the factors of lithology,tectonic movements,depth,here forming the advantageous reservoir conditions which are I type fine reservoir of erosion crust belt in the top,and II type well reservoir of seepage undercurrent belt under the erosion crust belt.The two sets of area mud seal of Dongying formation and Shahejie formation overlaps the buried hills.With the huge thickness and great distributive area,Dongying formation mud seal is a set of whole area seal for the study zone.The second and third sections inside it have high pressure,so they are with great seal ability to the middle north buried hills.However,mud seal in Shahejie formation is much thinner,and only distribute in the middle and north parts,so it could only be regarded as a set of district seal.The first and third sections inside it has high pressure and the third section only overlap the JZ25-1S area,it is vital to the hydrocarbon accumulation in buried hills in JZ25-1S area.The main hydrocarbon reservoir type is hilltop bulk reservoir in Liaoxi Low Uplift buried hill,and the oil in such reservoir is almost mature but its physical properties varies,and the gas mainly is moisture,seldom high moisture and dry gas,the oil field water is primarily sodium bicarbonate type.The dominating factors for hydrocarbon accumulation in Liaoxi Low Uplift buried hills are reservoir,high pressure and the sport property of fault,and its accumulation modes could be divided to two types which are single direction single source single way type and double directions double sources double ways type.