沉积环境对阳信洼陷生物气成藏的控制作用

The control of sedimentary environment over biogas reservoir formation in Yangxin Subsag

生物气的形成依赖于微生物对有机质的分解,而微生物的存在及生理活性受沉积环境的制约。分析了地层温度、咸化环境和还原环境等因素对阳信洼陷沙一段生物气生成、聚集和保存的控制作用。研究结果表明,地层温度控制了微生物的生理活性及甲烷的产气量;咸化和还原环境及中性水介质条件有利于有机质的保存与生物气的生成;快速沉降的沉积背景减少了早期生成的甲烷扩散。该区沙一段的滨浅湖相沉积环境为生物气成藏提供了优质气源岩及生物滩微相生物灰岩和白云岩等有利含气储层,断裂不发育对生物气藏的保存十分有利。

The formation of biogas was based on the decomposition of organic material by microbes. The sedimentary environment controlled the existence and the physiological activity of the microbe. Temperature, salty environment, reducing environment and some other control factors on biogas forming, accumulation and preservation of the Es1 in Yangxin Subsag are analyzed. The formation temperature controls the physiological activity of the microbe and the production of the methane. The saline and reducing environment and the neutrality aqueous medium are favorable of the preservation of the organic material and the formation of the biogas. The depositional setting of rapidly subsidence could reduce the diffusion of the biogas that was formed early. The shore or shallow lake facies of sedimentary environment in Es1 of this area provides good gas source rock and a-vailable gas-bearing reservoir, including biolithite, biogenic dolomite. The fault did not grow that was favorable of the preservation of the biogas reservoir.