| Faults have an important influence on the formation and distribution of oil and gas reservoirs.The formation of 89% oil and gas reservoirs in Zhanhua-Chezhen Sag is related to faults.The predecessors made a great deal of work on the study of the Paleogene-Neogene faults and hydrocarbon accumulation in Zhanhua-Chezhen sag,mainly focusing on the level of faults,the activity of faults,the combination of faults,the conductivity of faults And plugging,etc.,it is necessary to deepen our understanding of the tectonic features of Fault-Fromation combined structure and the study of the relationship between Fault-Fromation combined structure and hydrocarbon accumulation based on the concave-silom combined structure.In this paper,we selected the Chexi-1 concave-silom band,Chengzikou-5 concave-silom band,Gudao-1 concave-silom band and around Gudao concave-silom band as research areas.Taking the Paleogene-Neogene faults and hydrocarbon accumulation in the Zhanhua-Chezhen Sag as the main research object,we made a great deal of work on the study of the Fault-Fromation combined structure(fault surface structure,Plane Fault-Fromation combination,profile Fault-Fromation combination,fault disconnected horizon,the fault activity,fracture gap maintenance)and the relationship between the Fault-Fromation combined structure and hydrocarbon accumulation,achieved the following three aspects:(1)Fault-Fromation combined structure(1)Fault surface structureThe three-dimensional seismic data was used to map the fault plane of No.1 fault,No.2 fault,Gubei fault,Gunan fault,Caojiazhuang fault and Da 71 fault.The top of the faultplane is characterized by different heights.The fault plane is mainly monoclinic,and the valley and ridges are also developed.(2)Plane Faults-Rock FormationsBased on the relationship between fault strike and stratigraphic contours,the plane Fault-Fromation combination combination is divided into cut-slope fault(the fault strikes and the contours of the rock formation on both sides are parallel to each other)and along-slope fault(Fault strikes and oblique strikes of the contours of the rock formations on both sides),the Caojiazhuang fault is the cut-slope fault,the No.1 fault,the No.2 fault,the Gubei fault,the Gonan fault,and the Da 71 fault are along-slope fault.(3)Profile Fault-Fromation combinationProfile Fault-Fromation combination refers to the relationship between the section trend and the rock formations on both sides.The pattern of Profile Fault-Fromation combination in the study area is dominated by ridges,valleys,half-ridge and half-trough.(4)The fault disconnected horizonThe fault disconnected horizon includes two types of faults: fault-to-surface type and don't fault-to-surface type.The No.1 fault,the No.2 fault,the Gubei fault,the Gunan fault,and the Caojiazhuang fault are faulted to surface faults.The Da 71 fault is not broken to surface faults.(5)The fault activityThe faults in the study area were divided into three types: early activity,intermittent activity,and continuous activity by comparing the thickness of the two layers of the fault.The Caojiazhuang fault,the fault No.2 and the Gubei fault and the Gunan fault were continuous active faults,and the Da 71 fault was intermittent active faults.(6)The fracture gap maintenanceThe fracture gap maintenance refers to the difficulty of maintaining and closing fault gaps.The maintenance and closure of cracks in fractured formations are related to the development of plasticity,elasticity,and cracks in the formation.The 0-1000 meters of the study area is a plastic compaction section,the fracture gap is not easy to maintain,1000-2000 meters is an elastic-plastic compression section,the fracture gap is easy tomaintain,and the rupture section is less than 2000 meters.The fracture gap is easy to maintain.(2)Relationship between hydrocarbon accumulation have been discovered and the Fault-Fromation combined structure(1)Relationship between hydrocarbon accumulation have been discovered and the Fault surface structureHydrocarbon accumulation are usually located at the top of the fault plane,or at the cross-section ridges.For example,the Ng hydrocarbon accumulation in Gudao is located at the top part of the fault plane in Gubei and Gunan faults,and the Ng hydrocarbon accumulation near the fault in northern Chengbei is located in the ridge of the fault section.(2)Relationship between hydrocarbon accumulation have been discovered and plane Faults-Rock FormationsIn the along-slope fault,the oil and gas reservoirs are distributed along the high fault line,or the location of the fault head,sometimes bead-like.For example,the Gunan fault is a along-slope fault,and the T2 reservoir located in the eastern section of the fault is located along the high fault section;For the cut-slope fault,the reservoir is sometimes distributed at both ends of the fault line,sometimes in the middle.(3)Relationship between hydrocarbon accumulation have been discovered and profile Fault-Fromation combinationHydrocarbon source rock reservoirs are usually distributed in ridge Fault-Fromation combined structure,and there are few distributions of valley Fault-Fromation combined structure.Overburden reservoirs on source rocks are usually distributed in valley Fault-Fromation combined structure,and ridge Fault-Fromation combined structure are less distributed.Such as the area in the Gunan fault around the Gudao Island,the T2 seismic reflection layer of the Gunan fault is valley Fault-Fromation combined structure,both sides of the fault are ridge Fault-Fromation combined structure,forming a small area of T2 hydrocarbon reservoirs.(4)Relationship between hydrocarbon accumulation have been discovered and thefault disconnected horizonFor fractures to surface faults,the reservoir is usually located below the plastic segment.For other faults,the distribution of oil and gas reservoirs is located below the highest part of the fault.For example,in the area in the Gubei fault around the Gudao Island,there are a series of small faults in the area that have not broken down to the T1 seismic reflection layer,and no T1 hydrocarbon reservoir is found.(3)Control of hydrocarbon accumulation in the Fault-Fromation combined structureEarly active faults and continuously active faults can divide the Sha-3 and Sha-4 oil and gas reservoirs;Profile Fault-Fromation combination,fault disconnected horizon and fracture gap maintenance affect the vertical distribution of the Sha-1,Sha-2,dongying,guantao,minghuazhen oil and gas reservoirs;The Plane Fault-Fromation combination and fracture gap maintenance affect the location of Sha-1,Sha-2,dongying,guantao,minghuazhen oil and gas reservoirs on the plane. |
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