乐山－龙女寺古隆起大中型气田成藏条件研究

RESEARCH ON RESERVOIR-FORMED CONDITIONS OF LARGE-MEDIUM GAS FIELDS OF LESHAN-LONGNUSI PALAEOHIGH

四川盆地乐山－龙女寺古隆起是受基底隆起控制的具有一定继承性的隆起，经历了多期同沉积隆起兼剥蚀隆起，最终定型于前二叠纪，因此称之为前二叠纪古隆起更为确切。在二叠纪之后的古构造演化中，下古生界古构造轴线向东南偏移，形成了现今老龙坝－威远－龙女寺的中央隆起。这个巨大的隆起控制着下右生界及震旦系的天然气聚集，具有广阔的勘探前景。其中以隆起带上的大型构造、碳酸盐岩古风化壳及华銮山构造带等为重点勘探目标。气藏类型较多。该隆起带已获震旦系灯影组气田、含气构造、含气区块各１个，奥陶系古风化壳气井１口，获得了较丰富的气储量。尽管该区存在着隆起带目的层埋藏较深、储层非均质性较强、构造较平缓等不利因素，但研究认为，只要选择好重点区块或目标，坚持勘探，加强科研，将获得更为丰富的天然气储量。

Leshan-Longnusi paplaeohigh controlled by basement uplift is an inheriteduplift,being undergone multistate syndepositional and denudation uplift and formed in Pre-permian period at last,so,it is precisely named Pre-permian paplaeohigh. In the courseof palaeostructural evolution after Permian,the axial line of Lower Palaeozoic palaeostructure has been diverged to southeast to form nowaday Laolongba-Weiyuan-Longnusi central uplift which controls the gas accumulation in Lower Palaeozoic and Sinian and has vastexploration prospects. The large structures,carbonate rock palaeo-weathering crust, Huoyingshan structure belt etc. on the central uplift are the main exploration goals. In it,thereare mang types of gas reservoirs and Sinian Dengying formation gas field, one gas-bearingstructure, one gas-bearing block and one well of Ordovician weathering crust have beenfound and rich reserves are obtained. Although there are some unfavourable factors such asdeep target zone, stronge heterogeneous reservoir and gentle structure etc. in the area, richgas reserves will be obtained under the conditions of well selecting key blocks and goals, insisting on exploration and strengthening the researche on science-technology.