The Study On Distribution Characteristics And Controlling Factors Of Carboniferous Volcanic Reservoir Of The Northwestern Margin, Junggar Basin

The study on distribution of reservoir and controlling factors is an essential method for reservoir description and evaluation, which is also the foundation of exploiting oil and gas accumulation efficiently. Because of the extraordinary complication and aeolotropism of volcanic reservoir, how to characterize finely the distribution of reservoir and controlling factors of reservoir formation, has become a technical core and bottle-neck in reservoir research of volcanic oil and gas accumulations, which is also the key to develop this kind of hydrocarbon reservoir successfully.The paper takes the Carboniferous volcanic reservoir of the northwestern margin in Junggar Basin as the research object. Considering the difficulties in the study on the volcanic reservoir, such as stratigraphic classification and correlation of volcanic strata, the type of spaces and consociation, the diagenetic evolution of pore space and reservoir, identification and evaluation of fissure and fracture system, comprehensive evaluation of reservoir, interdisciplinary study has been carried out for volcanic reservoir. Based on kinds of static and dynamic data, the paper employs traditional methods and modern techniques together to study on the facies and lithology, pores, fractures and so on. The controlling factors of volcanic formation, tectonism, diagenesis and so on, were analysed comprehensively, meanwhile, the distribution regular of volcanic reservoir were delineated in detail, the method of integrative evaluation on unique lithologic & fractured reservoir was found out.After exact and careful work, this paper comes to following conclusions:â‘ The dividing program of the Carboniferous volcanic formation has been established including eruptive cycle, eruptive stage and filtration unit; the features of the filtration unit ,including lithology and facies, physical property, properties of seismic reflection etc., that is applied firstly in the volcanic reservoir, was studied particularly. Basic and intermediate volcanic in island arc and discordogenic fault controls the volcanic distribution.â‘¡The volcanic facies of interest region include effusion facies, explosion facies, eruption-sedimentary facies, subvolcanic rock facies and volcanic neck facies, basalt, andesite, tuff and sediment tuff are the main reservoir rocks.â‘¢12 types of diagenesis and 5 types of evolutionary phase make 19 types of primary and secondary pore and fracture. The most important secondary pore is formed by the feldspar, zeolite etc. resolved in acid water via surface of unconformity and fault.â‘£basing static and dynamic data, the parameters and standard of reservoir classification were built up.The study results have been applied to the development plan of the Carboniferous volcanic reservoir of the northwestern margin in Junggar Basin and used to direct well pattern design and well deployment. The study method can be referred to the research of complicated volcanic oil-gas reservoir. The study conclusion is significant to improve and enrich volcanic reservoir research.