Advances on enrichment law and key technologies of exploration and development of continental tight oil in China (2016–2018)

Abstract

Continental tight oil is a promising unconventional resource found in recent years and an important supplement to the growth of domestic petroleum reserves and production in China. Guided by the research objectives set by the China National Science and Technology Major Project “Enrichment Law and Key Technologies of Exploration and Development of Tight Oil,” and based on laboratory experiments and field tests by eight PetroChina petroleum companies, three signs of progress in theoretical technology and practical exploration and development have been made to continental tight oil in China. (1) Forming conditions: It is found that laminated organic-rich shale is primary source rock. Furthermore, many types of favorable reservoirs, such as terrigenous clasts and internal clasts, are developed and accumulate into two kinds of large-scale and continuous distribution of in-source and near-source assemblages. (2) Enrichment Law: Favorable reservoir facies zones, being near the hydrocarbon source center, and having a supportive tectonic background are three common factors controlling oil enrichment and high production. The proven tight oil resources are 10.65 × 109 t, whereas 40 enrichment zones have been identified and a number of drillable “sweet sections” have been found. (3) Key technologies of exploration and development: Key technologies have been developed involving multi-scale tight reservoir characterization, resource classification evaluation, seismic response and engineering evaluation of “sweet sections,” as well as reservoir stimulation and effective development. The research results support the rapid continental tight oil in China. By the end of 2018, proven tight oil geological reserves were 437 × 106t, while proved, controlled and predicted reserves were 3.019 × 109t, and the new production capacity was 3.31 × 106t. It is suggested that follow-up studies should focus on three fields—clastic rocks, peperite-sedimentary tuff, and lacustrine carbonate rocks. The above should be done in five aspects – enrichment law, sweet area evaluation and prediction, key development technology, efficient reservoir stimulation, and practical application in key basins so as to support steady integration of geology and engineering for developing continental tight oil in China. Keywords: Continental strata, Tight oil, Sweet section, Exploring oil inside source kitchen, Enrichment law, Key technology, Unconventional oil