Study On The Classification And Evaluation Of Oil Reserves In Southeast Region Of Ansai Oilfield

Oil and gas are important energy, several major oil companies in China- China National Petroleum Corporation(CNPC), China Petrochemical Corporation(Sinopec), China National Offshore Oil Corporation(CNOOC) and Shaanxi Yanchang Petroleum Group Co., Ltd.(Sxycpc) have being listed overseas, at the same time they were facing the sissues of diferrences in methods of calculation and evaluation of oil and gas with international standards. With the international standards, Domestic oil and gas resources and reserves definition, classification and evaluation methods must meet the SEC(Security and Exchange Commission) regulatory requirements. Traditional methods are quite different from the overseas requirements. Different companies have different concepts and content of definitions in oil and gas resources or reserves as well as classification criteria, evaluation methods, parameters of evaluation and results of expression, which bring difficulties in international cooperation with several major oil companies in China.Based on the detailed study on regional tectonic and sedimentary evolution history and analysis of the reservoir characteristics, also after fully analysis of the definations and classifications of domestic and overseas oil and gas reserves, apply the two assessment system to the Southeastern Ansai Oilfield in Ordos Basin as a case by using static method(volumetric method). Duo to the strict standards with SEC, we get the even 50% caculation results lower than it is with domestic standards.The different concepts and caculation results shows that overseas institutions such as SEC hold the higher strict evaluation standards and pay more attention to proved data, suggesting that the information provided by seismic data should be discreetly apply with or even completely inadmissible; also focusing on the economical efficiency and economic information timeliness in entire production process, and always apply the economic philosophy into the entire oil and gas exploration and development. Therefore, there should be a specific comparison between the domestic evaluation criteria and the prevalent overseas standards and find out their similarities in definitions and classifications, finally establish the regional standards and evaluation system in line with international standards which can accommodate advantages from different standards, it is not only easier for companies to exchange research and business information,but also provide strong support for the entire oil and gas development.