万米钻探工程的石油地质理论依据与勘探方向

Basis of petroleum geological theory and exploration direction for ultra⁃deep exploration of 10000⁃meter depth

油气资源是关系着我国经济发展的重要战略资源。我国陆上主力油田经过50余年开采,油田含水率已超90%。我国石油和天然气对外依存度已分别由2013年的58.9%和29.2%提高到2022年的71.2%和40.2%,已进入石油安全警戒线,影响国家安全。为了寻找更多接替储量,油气勘探向“更深、更复杂”超深层的万米勘探新领域推进,近期国内油公司相继实施了“深海一号”、“深地一号”油气勘探计划,探索实践了智能导钻新技术,推动了万米勘探计划的实施,9 000 m以深的井也发现了油气藏。通过近期的勘探实践,从超深层成烃、成储与成藏机理等方面,论证了万米钻探的石油地质理论依据,指出超深层具有多途径生烃,已经突破120~160℃的生烃门限;“三元控储”理论指出,大于4 500 m的深层、超深层仍发育有效的储集体;多期成藏与保持是超深层规模油气藏发育的有利条件。四川盆地海相深层资源总量约为15.22×10^(12) m~3,其绵长裂陷槽周缘震旦系、川中古隆起周缘龙王庙组、城口海槽南侧米仓山—大巴山地区龙王庙组、川西上古生界深层等具有千亿立方米的资源规模。塔里木海相深层总资源量约为152.62×10~8 t油当量,其中塔北隆起、塔中隆起、麦盖提斜坡的中下奥陶统岩溶以及满加尔西缘中下寒武统台缘带、阿瓦提—顺托果勒中下寒武统台内滩等是具有亿吨级规模的勘探领域。鄂尔多斯盆地西南缘的中新元古界近期也有重要的油气发现。准噶尔盆地准中深洼带、塔里木盆地库车坳陷深层等碎屑岩领域也是万米勘探的重要领域。

Oil and gas resources are of important strategic importance for China’s economic development.After more than 50 years of mining in main oil fields,the water cut of oil fields in China has exceeded 90%.China’s external dependence on oil and natural gas has increased from 58.9%and 29.2%in 2013 to 71.2%and 40.2%in 2022 respectively,reaching the oil security warning line and impeding national security.In order to find more replacement reserves,oil and gas exploration has been promoted to the“deeper and more complicated”ultra-deep exploration area of 10000-meter depth.Recently,domestic oil companies have successively implemented the“Deep Sea No.1”and“Deep Earth No.1”oil and gas exploration plans,which have explored and practiced new technologies of intelligent drilling and promoted the implementation of the 10000-meter exploration plans,and reservoirs have been encountered by wells over 9000 m deep.Based on recent exploration practice,this paper demonstrates the basis of petroleum geological theory for exploration of 10000-meter depth from the aspects of ultra-deep hydrocarbon generation,storage and accumulation mechanisms,and it suggests that multi-source hydrocarbon generation can be identified in ultra-deep strata and the hydrocarbon generation threshold has exceeded 120-160℃.The“three-element controlling reservoir”theory points out that deep and ultra-deep reservoirs can be developed at depths greater than 4500 meters and multi-phase hydrocarbon accumulation and preservation constitute a favorable condition for the development of ultra-deep large-scale oil and gas reservoirs.The Sichuan Basin has the total resources of about 15.22×1012 m3 in deep marine strata,wherein the Sinian system on the margin of Mianyang-Changning taphrogenic trough,the Longwangmiao Formation on the margin of central Sichuan palaeo-uplift,the Longwangmiao Formation in Micang Mountain-Daba Mountain areas to the east of Chengkou oceanic trough,and the Upper Paleozoic in western Sichuan have a resource potential of more than hundreds of billions of cubic meters.The Tarim Basin has about 15.262×109 tons of equivalent oil in deep marine strata,wherein the Middle-Lower Ordovician karst area in the Tabei uplift,Tazhong uplift and Maigaiti slope,the Middle-Lower Cambrian platform marginal zone on the western margin of Manjiaer Sag,and the Middle and Lower Cambrian intraplatform shoal of Awat-Shuntuoguole are all oil potential areas of hundreds of millions of tons.There are important oil and gas discovery in the Middle Neoproterozoic in the southwest edge of Ordos Basin.Additionally,the field of clastic rocks such as the deep strata in the central deep depression zone in Junggar Basin and the Kuqa Depression in Tarim Basin are also important areas of exploration of 10000-meter depth.