Analysis On The Relationship Between Faults And Mesozoic And Paleozoic Oil And Gas Reservoirs In Ordos Basin

With the gradual deepening of oil and gas exploration and development in the Ordos Basin,it is recognized that the internal faults in the basin are not only developed,but also closely related to oil and gas reservoirs.However,due to problems such as the accuracy of seismic data,the understanding of fault characteristics is not sufficiently specific and in-depth,which further affects the study of its relationship with the formation and distribution of oil and gas reservoirs.This article uses seismic data of good quality since 2012 to identify and calibrate the main faults in the basin determined by remote sensing,gravity and magnetic field data,etc.on the profile,and characterize the structure of the fault;analyze the fault-rock combination structure Characteristics(the relationship between the fault and the rock on both sides)and the activity of some faults;on this basis,the relationship between the fault and the discovered oil and gas reservoirs in the Mesozoic and Paleozoic is analyzed.Obtained the following main understanding:(1)This time,18 faults in different directions of the basin were calibrated and structured.Most faults have the characteristics of nearly upright occurrence and no obvious fault distance.Among them,the width of the northeast fault,northwest fault,and north-south fault in the west of the basin is generally larger than that in the east;according to the trend of the fault and the structural contour on the plane The intersecting relationship divides it into a along-slope fault(the fault strikes obliquely with the rock structure contours on both sides)and a flat slope fault(the fault strike is nearly parallel to the rock structure contours on both sides),the Mesozoic and Most Paleozoic faults are along slopes;fault fault horizons have the following conditions: from basement to surface,from basement to Paleozoic,from basement to Mesozoic,from Mesozoic to surface and Disconnect the Mesozoic world.(2)The fault activity was analyzed by studying the thickness of strata on both sides of the fault.The thickness of most faults from the Tk reflection layer to the surface on both sides of the surface is quite different,and the main erosion period of the basin is Late CretaceousNeogene.It is believed that the fault has strong activity from the late Late Cretaceous to the Neogene.The thickness of the Chang 7-Chang 3 formation in the Jun area varies greatly on both sides of the F6 fault,which can reach 117 m,indicating that the fault is active during the deposition period of Chang 7-Chang 3 and is a co-sedimentary fault.(3)The Mesozoic Yanchang Formation Chang 8-Chang 10 Reservoir,Chang 4 + 5-Chang 1 Reservoir and Yan'an Reservoir discovered in the basin are distributed near the fault and the fault,indicating that the fault plays an important role in the transportation and migration of oil and gas generated by the main source rock length 7 to these reservoirs;the 19 Chang 7 mud shale industrial oil flow wells that have been discovered are all distributed near faults and faults,indicating that the faults are related to mud shale.The improvement of oil and gas reservoirs has an important impact.(4)More than 90% of the more than 1,000 high-yield natural gas wells(exploration wells and some development wells)with a production capacity of more than 50,000 cubic meters in the upper and lower Paleozoic of the basin are distributed within the fault or within a range of less than 10 km from the fault,indicating the fault It has a positive impact on natural gas enrichment.