Study On Hydrocarbon Accumulation Law For Volcanic Rockreservoirs In Hongche Fault Belt, Junggar Basin

Hongche fault belt，which is one of the long-term point area for hydrocarbon migrationof Shawan sag and Pen-1well west sag, is located in the foreland thrust belt of JunggarBasin. This area is rich in oil and gas resources, has favorable structural location and welldeveloped fracture. With the characteristics of "filled with oil in the whole area", Paleozoicvolcanic reservoirs in the study area have the scale of substantial reserves and greatexploration potential. But compared with conventional reservoir, the reservoir conditionsand main control factors of volcano rock reservoir are more complex, and we lacksystematic research on hydrocarbon accumulation for volcanic rock reservoir in this area.Therefore, it is necessary to research on volcanic rock reservoirs system, to summarizes theoil and gas accumulation rule, to establish accumulation model, for indicate the direction ofnext exploration deployment.Combined with the drilling data, using the volcano rock lithology identificationmethod of logging crossplot, we can summarize the following conclusions. Carboniferouslithology is mainly volcanic rocks, clip with a small amount of sedimentary rocks. And thelava has majority basalt, andesite followed, containing a small amount of acidic rhyolite,and the Pyroclastic rocks are mainly tuff and volcanic breccia. Carboniferous exists threeeruptions combination on vertical in Hongche fault belt. Each combination share similarcharacteristics, which formed the gradient sequence of the volcanic eruptionphase-overflow-volcanic sedimentary facies-pyroclastic phase. And the eruption center innorthern and eastern is more than others.Through the analysis of volcanic rock reservoir, it show that the volcanic breccia in eruption facies has the best reservoir performance，followed by the overflow basalt. Thereservoir has high porosity，low permeability and strong anisotropy. The reservoir physicalproperties has little relation with depth, and has poor Porosity and permeability correlation.The volcanic rock reservoir in Hongche fault belt is closely related with area fault structure,fractures and the volcanic rock lithology and lithofacies.The crude oil of volcanic rock reservoir in Hongche fault belt has three sources, whichis from Fengcheng formation, Urho formation and mixed source. After several times ofhydrocarbon charging, the reservoir has through at least two accumulation and oneadjustment period, Finally, it form the present reservoir, with the features of multiplestages and multiple sources. Based on the dissection of representative wells, we find that thevolcanic reservoir in research area is heterogeneous fault block and fault-lithologic reservoir,which is controlled by the ancient volcanic edifice and the lithologic. Volcanic rock oil andgas reservoirs have many effect factors, such as the faults, unconformities and lithofacies，etc. In plane, the reservoir is controlled by the distribution of fault and volcanic facies；inprofile, he reservoir is controlled by the ancient Highlands and igneous eruption sequence.