【摘要】 本文通过对四川盆地元古宇—下古生界勘探最成功的两个地区——威远震旦系气田和资阳震旦系含气区天然气成藏要素和成藏过程的详细比较,得出:①资阳含气区和威远气田的原始烃源相同,均是下寒武统生成的油裂解的天然气,不同的是资阳为残留的气顶气,威远是水溶气脱溶气。②资阳含气区和威远气田震旦系碳酸盐岩基质孔隙度相近,资阳地区溶蚀洞穴发育,但裂缝不发育,储层渗透性较差,非均质性强;威远地区储层洞穴不发育,但裂缝发育,形成统一的裂缝-孔洞系统。③威远地区具有统一的圈闭,闭合度高(800m),闭合面积大(895km2)。资阳含气区不具有统一的圈闭,多为局部的小高点。④喜马拉雅期隆升作用使资阳统一含气区分散化和气藏变小,形成多压力系统的含气区;威远地区快速大幅度隆升,溶于水中的天然气脱溶,形成具同一压力系统的整装气田。⑤资阳含气区的成藏过程为:(资阳—威远)古油藏→原油裂解→气顶天然气→隆升调整→现今(残留)含气区,其天然气藏是隆升调整成藏,是在原古气藏的基础上改造残留而成;威远地区的成藏过程则是:(资阳—威远)古油藏→原油裂解→天然气大量溶于水中→隆升使得带有大量天然气的水向威远运移和天然气脱溶→现今(新生)气藏,属天然气的脱溶成藏。资阳含气区受古构造的控制明显;威远气田则主要受今构造的制约。因此,在四川盆地震旦系和下古生界的油气勘探中,既要研究其古构造的特征和演化,也要研究今构造的特征和分布规律,才能发现不同类型的天然气藏。更多还原

【Abstract】 Weiyuan Sinian gas field and Ziyang Sinian gas-borne area are the only two natural gas pools from the Sinian system to lower Palaeozoic Erathem in Sichuan basin,west China.Depending on the elements and process of Sinian natural gas pools in Weiyuan gas field and Ziyang gas-borne area,the present paper has concluded at the following results.(1) The source rocks of the Sinian natural gas pools in Weiyuan gas field and Ziyang gas-borne area are the same,and both were the lower Cambrian system.The natural gases from the two areas are oil thermal cracked gas,but the gases in Weiyuan were also from the gas dissolved in formation water.(2) The porosities of the Sinian reservoir rock matrix(dolostone) in the two areas are similar.The cavities formed by karstification were developed very much in Ziyang gas-borne area,but undeveloped in Weiyuan gas field;the fractures were developed very much in Weiyuan gas field,but undeveloped in Ziyang gas-borne area.(3) The trap in Weiyuan is an entire anticline with high closure height(800 m) and big closure area(895 km2),but are small high topographical points without entire closure height and area in Ziyang.(4) Himalayas movement has made the Ziyang palaeotrap isolated and the Ziyang palaeo natural gas pool become smaller,but made the Weiyuan area uplifted,dissolved gas escaped from water in Weiyuan,and formed an entire Weiyuan natural gas pool with the same pressure system.(5) The formation process of Ziyang Sinian gas-borne area is:(Ziyang—Weiyuan) palaeo-oil pool→oil thermal cracked→oil-cracked gas pool→gas pool modified by uplift→present gas borne area.The formation process of Weiyuan Sinian gas field is:(Ziyang—Weiyuan) palaeo-oil pool→oil thermal cracked→the gas largely dissolved in water→the water with dissolved gas migrated to Weiyuan area by uplift and escaped from water in Weiyuan→present gas field.The formation of Ziyang Sinian gas-borne area was mainly controlled by the palaeo-structures;however the formation of Weiyuan Sinian gas field was chiefly formed by the modern(Himalayas) structures.Therefore,both the palaeo-structures and the modern structures should be studied during the hydrocarbon study and exploration on the Sinian system to lower Palaeozoic Erathem in Sichuan basin.更多还原