缅甸若开海域生物气藏气源成因分析

发布时间：2018-03-25 12:15

本文选题：生物气藏　切入点：气源成因　出处：《油气地质与采收率》2017年02期

【摘要】：缅甸若开盆地深水区域具备良好的生物气成藏条件和勘探前景,生物气藏作为一种非常规天然气藏,其成藏条件较为苛刻,研究生物气藏的气源成因,是成藏因素分析的首要问题。通过地震正演建模、地球化学分析等方法,证实缅甸若开海域中方勘探区含气地震响应特征明显,且为生物气藏。若开海域生物气烃源岩表现为"三低、一高、弱成岩"的地质特征,即较低的有机碳下限值、较低的热演化程度、低地温环境、较高的沉积速率、岩石固结程度处于弱成岩阶段中早期。峡谷泥岩、中新统泥岩、上新统泥岩均可以为甲烷菌提供食物—物质来源,上新统以上的泥岩不具备形成生物气的物质基础。推测研究区可能存在天然气水合物,且受到外界因素影响,使得压强和温度改变,导致天然气水合物的稳定状态改变,致使其排出大量生物甲烷气,进而在圈闭内聚集成藏,表现为气体不断形成、不断增压—突破封存压力界限—气体泄漏—再次压力平衡—气体再生成、再增压—再突破封存压力—气体再泄漏—再平衡的排驱模式。
[Abstract]:The deep-water area of Ruokai Basin in Myanmar has good conditions for biogas accumulation and exploration prospects. As a kind of unconventional natural gas reservoir, biogas reservoir is formed under harsh conditions, so the origin of biogas is studied. Through seismic forward modeling, geochemical analysis and other methods, it is proved that the response characteristics of gas-bearing earthquakes in the Chinese exploration area of Ruokai sea area in Myanmar are obvious. The source rocks of biogas in Ruokai sea area are characterized by "three low, one high and weak diagenesis" geological characteristics, that is, lower limit value of organic carbon, lower thermal evolution degree, lower geothermal environment and higher deposition rate. The degree of rock consolidation is in the early stage of weak diagenesis. Canyon mudstone, Miocene mudstone and Pliocene mudstone can provide food and material source for methane bacteria. The mudstone above Pliocene has no material basis for biogas formation. It is speculated that natural gas hydrate may exist in the study area, and it is affected by external factors, which makes the pressure and temperature change, resulting in the change of the stable state of gas hydrate. It emits a large amount of biogenic methane gas, and then accumulates into a reservoir in the trap, which is manifested by the continuous formation of gas, the continuous pressurization-breakthrough of the seal pressure limit-gas leakage-re-pressure balance-gas re-generation, Repressurized-break through the storage pressure-gas re-leakage-rebalance displacement mode.
【作者单位】：中国石油大港油田分公司勘探开发研究院;中国石油渤海钻探工程公司测井分公司;
【基金】：中国石油海外科技专项“缅甸若开盆地深水区域油气风险勘探”(CNODC/CAL/KJZX/2015-016)
【分类号】：P618.13

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