【摘要】 截至2010年底,中国已发现45个大气田,累计探明天然气地质储量6.28×1012 m3,占全国总探明天然气储量的83.8%。中国大气田主要分布在鄂尔多斯、四川和塔里木三大克拉通盆地,层系上主要分布在二叠系和三叠系。大气田储集层岩性主要为碎屑岩类,其储量占大气田总量的64.9%;其次是碳酸盐岩类,占27.9%;火山岩类占7.2%。气藏类型以岩性型和复合型为主,分别占大气田总量的40.1%和34.2%。储量丰度主要为高、低储量丰度特征,低丰度气藏储量占52.4%,高丰度气藏储量占31.8%,储量丰度的高低与储集岩类型和气藏类型有关。大气田气藏压力以常压为主,不同类型气藏异常压力的形成与其独特因素有关。大气田发现及储量快速增长与成藏地质理论认识的进展密切相关。大型构造背景、充足的烃源条件、良好的输导通道、大型非均质性储集层以及巨厚膏盐岩和泥岩盖层是大气田形成的重要条件,各种要素的时空有效配置是形成大气田的关键。研究了典型气藏的形成条件与主控因素,建立了5类大气田(大面积低渗—致密砂岩大气田、常规砂岩超高压大气田、疏松砂岩生物气大气田、碳酸盐岩大气田、火山岩大气田)的成藏模式,明确了分布规律,深化了四大领域的天然气勘探理论:1发展了近源高效聚集的低渗—致密砂岩气藏勘探理论,推动了苏里格、川中须家河组气藏天然气储量快速增长;2创立了大型古油藏原油裂解的碳酸盐岩岩溶储层大气田勘探理论,引领了高石1井的重大突破和四川盆地震旦系—下古生界大气田勘探;3深化了碳酸盐岩台缘礁滩气藏勘探理论,有效指导了龙岗气田主体评价勘探与向西向东扩展以及四川盆地的天然气风险勘探;4创立了以生烃断槽为基本单元的火山岩气藏勘探理论,指导实现了松辽盆地深层中小断陷火山岩气藏勘探的系列突破。更多还原

【Abstract】 By the end of 2010,China had discovered 45 large gas fields(LGFs)with the accumulative natural gas proved reserves of6.28×1012 m3,i.e.,83.8% of the nation’s total proved natural gas reserves.These LGFs are mainly located in three large cratonic basins,including Ordos,Sichuan,and Tarim Basin.Stratigraphically,gas reservoirs in the LGFs are largely distributed in the Permian and Triassic formations.Regarding the lithologic nature,the reservoir formations mainly consist of clastic rocks followed by carbonate and volcanic rocks,in which 64.9%,27.9%,and 7.2% of the total reserves of LGFs are respectively found.The reservoirs are dominated by lithologic type and complex type,which account for 40.1%and 34.2% of the total reserves of LGFs,respectively.The reserves abundance of gas reservoirs is classified into high and low levels,and these two levels of reservoirs respectively contribute 31.8% and 52.4%to the total reserves of LGFs.The level of reserves abundance is related to the types of reservoir rock and gas reservoir.In the LGFs,reservoir pressure mainly occurs at the level of normal pressure.The formation of abnormal pressure in different types of reservoir is associated with their respective unique factors.The discovery of LGFs and rapid growth of gas reserves are dependent on new progress in understanding the geological theories of reservoir formation.Large-scale tectonic setting,sufficient source rocks,favorable transporting channels,large-scale heterogeneous reservoirs,and thick gypsum-salt and mudstone caprocks are the most important elements whose effective spatiotemporal configurations play a decisive role in the development of LGFs.Through the analysis of the formation conditions and major controlling factors of typical gas reservoirs,this study establishes the accumulation modes and clarifies the distribution patterns of five classes of LGFs(large-area low permeability-tight sandstone LGF,conventional sandstone ultrahigh-pressure LGF,unconsolidated sandstone biogas LGF,carbonate LGF,and volcanic LGF),further deepening the theories of natural gas exploration in four major fields.1)A theory of proximal,highly-efficient gas accumulation is developed for exploration of low-permeability-tight sandstone LGF,which promotes the rapid growth of natural gas reserves from reservoirs in Sulige gas field,Ordos Basin and Xujiahe Formation,middle Sichuan Basin.2)A theory of crude oil cracking inlarge-scale paleoreservoirs is established for carbonate karst LGF,which leads to a breakthrough in exploration of Well Gaoshi-1 and promotes the exploitation of Sinian-Lower Paleozoic LGFs in Sichuan Basin.3)A theory for exploration of carbonate platform margin reef-bank gas reservoir is deepened,which effectively guides the main exploration assessment of Longgang gas field and the extension of gas exploration to its west and east,as well as risk-taking gas exploration in Sichuan Basin.4)A theory with hydrocarbon-generating fault trough as basic unit is proposed for exploration of volcanic gas reservoirs,which helps to achieve a series of breakthroughs in exploration of medium-small faulted volcanic gas reservoirs in deep Songliao Basin.更多还原