The Control Function Of The Fault-sand Configuration On Hydrocarbon Migration And Accumulation

On the basis of research that fault and sand controlling hydrocarbon migration and accumulation, the control function of the fault-sand configuration on hydrocarbon migration and accumulation is studied. Considering the migration orientation, the control function of fault-sand configuration on hydrocarbon migration and accumulation is divided into lateral case and vertical case. Respectively, Nanpu sag as an example of the vertical case and Xingbei region as an example of the lateral case, the process and factors of fault-sand configuration migrating and accumulating hydrocarbon are analyzed.Under the condition of lateral migration, fault-sand configuration conducting hydrocarbon is divided into ladder-like migration and fault-sand conducting ridge migration along the fault strike. In Xingbei region, the ladder-like migration occurs in southwest slope zone and the central anticline belt. Fault-sand conducting ridge migration along the fault strike occurs in northwest slope area. Regional cap rock and better physical property and connectivity sand body are the conditions of ladder-like conducting. Fault-sand conducting ridge migration along the fault strike occurring needs four conditions. First, the strike of fault is agreed with the dip direction of formation. Second, the connectivity and physical property of sand body along the strike direction is good. Three, along the strike of fault has fluid migration potential gradient (or fault zone internal structure ridge development). Last, the thickness of cover layer above the sand body directly minus the fault displacement is greater than the threshold. Fault-sand configuration conducting ability is mainly controlling by sandstone thickness, sandstone dip angle and the shale content of sandstone. Its computation formula is:T= H·sinθ·(1-Rm).Under the condition of lateral migration, the main condition that fault-sand configuration accumulate hydrocarbon is barrier condition. Sand type dl is the most beneficial to hydrocarbon accumulation sand type. Through the laws research of hydrocarbon accumulation in Xingbei region found that:(1) Hydrocarbon in the footwall plate of reverse fault is more enrichment; (2) When the fault scale is larger, only a plate of fault gathers oil and gas. When the fault scale is small, oil and gas are gathered in two sets of fault. (3) Oil and gas reservoirs are raised on the vertical.Through the study of fault-sand configuration migrating hydrocarbon process under the vertical condition in Nanpu sag found that:Oil source faults and regional cap rock are the precondition of fault-sand configuration vertical migrating oil and gas. The higher sand-shale rate, the better physical properties of single sand and the favorable fault-sand configuration type are the conditions of oil and gas along the fracture occurring lateral distribution. Fault-sand configuration vertical conducting ability is mainly depended on the thickness of sand body, fault dip angle, the inclination of sand, fault-sand contact length and shale content. Its computation formula is:Under the condition of vertical migration, the condition of fault-sand configuration accumulation oil and gas is favorable traps existing on the both sides of fault. The laws of accumulation hydrocarbon are below. First, the thickness of regional cap rock determines the oil and gas distribution around the cover. Second, the high sand-shale rate determines specific horizon of lateral distribution. Last, fault-sand configuration type determines the specific types of traps and the specific place of hydrocarbon distribution...