论油气本源共同体——老油区发现新储量的探索思路

On the Community of Oil and Gas Sources: The Most Realistic Exploration Method to Discover New Reserves in an Old Oilfield

以克拉玛依油区为实例,提出了油气本源共同体新概念。指出深埋于新疆克拉玛依加依尔山下八大地质现象(巨大推覆体的加依尔山及其犁式断裂系统、玛湖新凹陷、山下古凹陷、中下地壳巨厚的低速高导层及其两侧的壳幔断裂、新疆隆起最高的莫霍面、深部上地幔软流圈形成隆起幅度达65 km的地幔柱),实际上就是生油—运移—散失—聚集—成藏—成带的隐工程。剖析这些深部构造后发现,裸露于加依尔山边百公里长多种类型丰富而罕见的油气苗和隐伏于地下沿克乌断裂带、玛湖断裂带聚集的油气富集带之油源,并非仅仅来自玛湖新凹陷,而更主要是来自深部三大烃灶(古凹陷内沉积物转化成烃、壳内低速高导层内由一氧化碳和氢合成幔源油气、地幔柱内由深部地幔流体聚合成烃碱流体),靠深、浅二套断裂系统上下沟通,形成既各自独立又相互联系、相互作用的不可分离的统一整体,即油气本源共同体。在我国华北、渤海湾、四川等油区都发育油气本源共同体,虽形态各异,但大同小异,提出应改变过去从上往下找油,顾上不顾下的传统做法,改为从下往上找油,上下兼顾的新思路。

Taking Karamay oilfield as an example,a new concept of oil and gas source community is proposed.Eight geological phenomena beneath the Gayer Mountain in Karamay(the huge nappe of Gayer Mountain,the plow-type fault system,the young sag of Mahu,the old sag of Shanxia,the thick low-velocity and high-conductivity layer in middle and lower crust,the crust-mantle fault besides the layer,the highest Moho surface in Xinjiang,up to 65 km high mantle plume from asthenosphere)constitute an integral hidden process of hydrocarbon generation-migration-loss-accumulation-entrapment.After analyzing these deep structures,the author realizes that the oil source which leads to hundreds kilometers long oil and gas seepage zones at the foot of Gayer mountain,oil and gas enrichment zones along Kewu fault zone and Mahu fault zone are not only from Mahu sag,but also mainly from three deep hydrocarbon kitchens:the hydrocarbons converted from sediments in the ancient sag,the mantle-derived hydrocarbons synthesized from carbon monoxide and hydrogen in low-velocity and high-conductivity layer in crusts,and the hydrocarbon-alkali fluids synthesized from deep mantle fluids in mantle plume.Three major source kitchens communicate with each other by two sets of fault systems of shallow fault system and deep fault system.These source kitchens are not only relatively independent,but also interact with each other.This inseparable unity is called oil and gas source community(OGSC).OGSC exists in many oil fields among China such as north China,Bohai bay and Sichuan oilfields.Different OGSCs have different shapes but generally similar.Traditional exploration method prospects from shallow strata to deep strata,focused on shallow strata.The exist of OGSC claims geologist to prospects from deep strata to shallow strata,a principle of "shallow-deep combination" should be complied.