Research On The Volcanic Reservoir Characteristics Of Yingcheng Formation Of Xujiaweizi Fault Depression

Exploration of the special reservoirs of Xujiaweizi fault depression have gained good effectiveness and show the cheerful prospect of gas exploration. This subject research on the volcanic reservoir characteristics of Yingcheng formation of Xujiaweizi fault depression, based on the laboratory core analysis data of 25 wells, 17 items more than 300 core samples.Applying the two experimental techniques, NMR and CT, to determine the type and distribution of porosity and fraction in the reservoirs of volcanic rock.This subject stablishes standard of evaluation and classification of reservoirs of volcanic rock, gives the lower limit value of effective porosity, that solve the difficult problems in the reserves calculation and guide the research and the production..This subject provided an gist for the breakthrough of exploration for the deep-seated natural gas. A material prediction about lithology, lithofacies, type and distributing of pore and the study in-depth about diagenism of reservoir were worked out. Identified that, the better volcanic reservoirs are rhyolite, andesite, agglomerate and crystal tuff in the place of weathering and corrosion. The type of pore includes primary vesicular, inneramygdale pore, intercrystalline pore, phenocryst corroded pore and structure fracture, exploding fracture. The developed places lie in Yingcheng oil formation of Shengping-Xingcheng-Zhaozhou.According to the standard of reservoir classification giving by this subject, the frontal three types of volcanic reservoirs can obtain industrial productivity after fracturing.â…£,â…¤volcanic reservoirs can not obtain industrial productivity after fracturing in the actual technological conditions. The lower limit value of effective porosity is 4%. The lower limit value of fracture reservoir may be under this value.Through the systems study for volcanic lithofacies and cause, type and diagenetic evolvement rule of pore and fracture, it can be obtained that better reservoirs mainly lie in the upper introfacies of eruptive facies or the zone of weathering and corrosion of the upper volcanic rock, Yingcheng oil formation of Shengping and Zhaozhou.Confirmed the cementation and solution are the main factors influencing the especial reservoir quality, and the location of cementation mainly occurs.