RESEARCH ON FRACTURE CHARACTERISTICS AND QUANTITATIVE CHARACTERIZATION OF VOLCANIC ROCK RESERVOIR

摘要

Volcanic rock reservoirs are large-scale oil and gas accumulations formed under the condition that magma in the deep underground is connected with source rocks and reservoirs in the upwelling process.Volcanic reservoirs in Xinjiang Oilfield,China are widely distributed and have great potential.However,volcanic rock reservoirs have complex fracture development and difficult quantitative characterization,which restricts the efficient exploration and development of volcanic rock reservoirs.In this paper,taking the volcanic rock reservoir of Xinjiang Oilfield as an example,we systematically carried out a quantitative characterization study of volcanic rock reservoir fractures,using a large amount of drilling,core,thin section,and logging data.The results show that the lithology of volcanic reservoirs in the study area includes basalt,andesite,dacite,rhyolite,granite,tuff and volcanic breccia,and the type of volcanic reservoir space can be divided into primary pores,secondary pores and fractures.The types of fractures developed in the study area mainly include structural fractures,condensation shrinkage fractures,and dissolution fractures.Among them,micro-fractures account for about 22% of the reservoir space.The electrical imaging fracture quantitative evaluation technology and the "fracture index" method are used to comprehensively characterize volcanic rock fractures.The interpretation results are reasonable,indicating that the technology is reliable to predict volcanic rock fractures.