Abstract:
Changlling gas field in southern Songliao basin is still in early development stage,and there is no clear understandings on reservoir characteristics and pore evolution regularities.In combination with core observation,thin section analysis and a variety of test data,the systematic studies on reservoir rock characteristics,pore structure characteristics,diagenesis and pore evolution regularities have been carried out.The results showed that:the sandstone reservoir of Denglouku formation is of high lithic and feldspar content,low compositional maturity,developed dissolved pores,and low coordination number.The pore throat combination is small and micro throat type.The diagenesis includes compaction pressure solution,cementation,metasomatism,dissolution and other four kinds.The initial porosity of sandstone is 34.1%,after compaction the porosity lost of 27.7%,after the cementation and metasomatism the porosity lost of 6%,while after the dissolution the porosity increased4.2%.At present,the porosity is about 4.6%.Low rock compositional maturity,dense cement type,high interstitial content and a strong role in the transformation of post-rock generation are found to be the main causes of dense reservoir.