In recent years, a series of large low and medium abundance oil and gas fields are discovered through exploration activities onshore China, which are commonly characterized by low porosity-permeability reservoirs, low...In recent years, a series of large low and medium abundance oil and gas fields are discovered through exploration activities onshore China, which are commonly characterized by low porosity-permeability reservoirs, low oil/gas column height, multiple thin hydrocarbon layers, and distribution in overlapping and connection, and so on. The advantageous conditions for large-area accumulation of low-medium abundance hydrocarbon reservoirs include： （1） large （fan） delta sandbodies are developed in the hinterland of large flow-uncontrolled lake basins and they are alternated with source rocks extensively in a structure like ＂sandwiches＂; （2） effective hydrocarbon source kitchens are extensively distributed, offering maximum contact chances with various sandbodies and hydrocarbon source rocks; （3） oil and gas columns are low in height, hydrocarbon layers are mainly of normal-low pressure, and requirements for seal rock are low; （4） reservoirs have strong inheterogeneity and gas reservoirs are badly connected; （5） the hydrocarbon desorption and expulsion under uplifting and unloading environments cause widely distributed hydrocarbon source rocks of coal measures to form large-area reservoirs; （6） deep basin areas and synclinal areas possess reservoir-forming dynamics. The areas with great exploration potential include the Paleozoic and Mesozoic in the Ordos Basin, the Xujiahe Formation in Dachuanzhong in the Sichuan basin, deep basin areas in the Songliao basin etc. The core techniques of improving exploration efficiency consist of the sweetspot prediction technique that focuses on fine characterization of reservoirs, the hydrocarbon layer protecting and high-speed drilling technique, and the rework technique for enhancing productivity.展开更多
Based on reserve abundance,large gas fields in China can be divided into two types：type one of high abundance large gas fields,dominated by structural gas reservoirs; type two of low abundance large gas fields,domina...Based on reserve abundance,large gas fields in China can be divided into two types：type one of high abundance large gas fields,dominated by structural gas reservoirs; type two of low abundance large gas fields,dominated by stratigraphic and lithologic gas reservoirs.The formation of these two types of large gas fields is related to the highly efficient accumulation of natural gas.The accumulation of high abundance gas fields is dependent on the rapid maturation of the source kitchen and huge residual pressure difference between the gas source kitchen and reservoir,which is the strong driving force for natural gas migration to traps.Whereas the accumulation of low abundance gas fields is more complicated,involving both volume flow charge during the burial stage and diffusion flow charge during the uplift stage,which results in large area accumulation and preservation of natural gas in low porosity and low permeability reservoirs.This conclusion should assist gas exploration in different geological settings.展开更多
文摘In recent years, a series of large low and medium abundance oil and gas fields are discovered through exploration activities onshore China, which are commonly characterized by low porosity-permeability reservoirs, low oil/gas column height, multiple thin hydrocarbon layers, and distribution in overlapping and connection, and so on. The advantageous conditions for large-area accumulation of low-medium abundance hydrocarbon reservoirs include： （1） large （fan） delta sandbodies are developed in the hinterland of large flow-uncontrolled lake basins and they are alternated with source rocks extensively in a structure like ＂sandwiches＂; （2） effective hydrocarbon source kitchens are extensively distributed, offering maximum contact chances with various sandbodies and hydrocarbon source rocks; （3） oil and gas columns are low in height, hydrocarbon layers are mainly of normal-low pressure, and requirements for seal rock are low; （4） reservoirs have strong inheterogeneity and gas reservoirs are badly connected; （5） the hydrocarbon desorption and expulsion under uplifting and unloading environments cause widely distributed hydrocarbon source rocks of coal measures to form large-area reservoirs; （6） deep basin areas and synclinal areas possess reservoir-forming dynamics. The areas with great exploration potential include the Paleozoic and Mesozoic in the Ordos Basin, the Xujiahe Formation in Dachuanzhong in the Sichuan basin, deep basin areas in the Songliao basin etc. The core techniques of improving exploration efficiency consist of the sweetspot prediction technique that focuses on fine characterization of reservoirs, the hydrocarbon layer protecting and high-speed drilling technique, and the rework technique for enhancing productivity.
基金sponsored by the National Key Basic Research Program of China(2007CB2095)
文摘Based on reserve abundance,large gas fields in China can be divided into two types：type one of high abundance large gas fields,dominated by structural gas reservoirs; type two of low abundance large gas fields,dominated by stratigraphic and lithologic gas reservoirs.The formation of these two types of large gas fields is related to the highly efficient accumulation of natural gas.The accumulation of high abundance gas fields is dependent on the rapid maturation of the source kitchen and huge residual pressure difference between the gas source kitchen and reservoir,which is the strong driving force for natural gas migration to traps.Whereas the accumulation of low abundance gas fields is more complicated,involving both volume flow charge during the burial stage and diffusion flow charge during the uplift stage,which results in large area accumulation and preservation of natural gas in low porosity and low permeability reservoirs.This conclusion should assist gas exploration in different geological settings.
