沉积盆地深部地层超压指标转化及评价方法——以湘黔鄂渝交界区为例

INDEX TRANSLATION AND EVALUATION METHOD OF OVERPRESSURE IN DEEP FORMATION OF SEDIMENTARY BASIN——A CASE STUDY AT THE BOUNDARY AMONG HUNAN, GUIZHOU, HUBEI AND CHONGQING

冯常茂 吴冲龙

Feng Changmao Wu Chonglong

中国地质大学, 武汉, 430074 2. 广州海洋地质调查局, 广州, 510760

China University of Geosciences, Wuhan, Hubei 430074, China 2. Guangzhou Marine Geological Survey, Guangzhou, Guangdong 510760, China

沉积盆地超压的成因类型主要有3种:地层不均衡压实、构造挤压和流体作用;其形成机理有欠压实、蒙脱石脱水、烃类生成、流体热增压、液态烃类的热裂解作用等。但深部地层超压的产生主要与水热效应增压、上覆地层压力和烃类生成及裂解作用有关,因而地层超压系数可以用水热效应增压系数、静岩增压系数和烃类增压系数三者之和来表示。确定是否存在超压时,除考虑地层超压系数外,还应用断裂进行一票否决制。利用该指标转化方法,对湘黔鄂渝交界区下寒武统牛蹄塘组的超压进行研究,结果表明,该区牛蹄塘组形成超压的最可能区域为宜宾一带。

Overpressure in sedimentary basins can be summarized into 3 types: disequilibrium compaction function,tectonic extrusion and liquid function.The forming mechanism includes undercompaction,montmorillonite dehydration,hydrocarbon generation,hydrothermal pressurization and hydrocarbon cracking,etc.But in deep formations,overpressure is mainly related to hydrothermal pressurization,superjacent strata pressure,hydrocarbon generation and cracking.So,overpressure coefficient in deep formation can be transformed by adding hydrothermal pressurization coefficient,superjacent strata coefficient and hydrocarbon pressurization coefficient.To estimate overpressure developed area,faults should be taken into consideration.Overpressure of the Lower Cambrian Niutitang Formation at the boundary among Hunan,Guizhou,Hubei and Chongqing has been studied.The most favorable region for overpressure locates around Yibin.

湖北省自然科学基金项目(2007ABA338);国家“十一五”科技攻关项目(2004BA616A—06—01)

https://doi.org/10.11781/sysydz200804414