Hydrocarbon Accumulation Conditions And Favorable Area Prediction Of Shajiao Formation In Dongpu Depression

Dongpu sag ES3formation is main lake sedimental system,the shale is main source rock of the conventiona oil and gas.Durin Early Stage of drilling and logging, ES3shale section appeared preferable Oil/gas shows,which indicate shale oil and gas preferable potential in the region. On the theoretical base of structural geology, sedimentary petrology, geochemistry, reservoir geology, logging geology and the previous research data collection, combined with on-site shale cores boserving and all kinds of analysis and testing,the paper systematically analyse reservoir forming conditions such as thickness,depth,organic geochemistry,reservoir property and gas content of ES3shale formation, on the base of above analysis,acomplish shale oil and shale gas prospective area,favorable area evaluation.The conclutions are following:(1) The Dongpu Sag ES3formation which is main lake sediment system,have the Characters of large thickness, widespread,moderate depth, poor homogeneity.(2) Organic matter abundance area of ES3shale that is mainly distributed in the northern area of deep lake and half deep lake facies and around,mainly controlles by the sedimentary environment,with the northern better, southern relatively poor distribution characteristics The type of organic matter is mainly mixed type, of which the northern region is main Ⅰ and Ⅱ1,middle area is main type Ⅱ1and Ⅱ2, South area is main type Ⅲ andⅡ2. Thermal evolution degree of ES3shale Is mainly affected by the depth,when depth is2450m,Ro is0.5%, depth is3150m,Ro is0.7%,depth is4250m,Ro isl.3%,the shale buried depth is less than4500m,Ro less is main less than1.2%which is main In stage of oil generation(3) Analysis and testing show that shale is mainly composed of clay, quartz, plagioclase, calcite, dolomite, anhydrite and small amounts of pyrite and siderite mineral. The pore types of shale are clay intergranular micropore, calcite intercrystalline and transgranular dissolved micropore, organic matter dissolved micropore,organic matter shrinkage micropore, microfracture and high-angle shearing tensional fractures, hydraulic fractures, diagenetic fracture.(4) The salt beds mud and shale chloroform bitumen "A" average content is0.726%, capable of generating hydrocarbon Pg is12.95%on the average, the total gas average content is2.3m3/t, which appear higher Genetic Potential and gas content.(5) Prediction results show that the northern region is shale oil favorable, the central region is shale gas favorable. Shale oil favorable zone mainly distributed in Hubuzai-Huzhuangji-Qianliyuan-XuzhenjiWenliu-Baiyige and Pucheng areas,where is main salt bed,deep lake,semi-deep lake sedimentary environment.Shale gas favorable area mainly distribute in the central region of the Qiaokou and Hu zhuangji, Qianliyuan deep depression alarpart area.