Study On The Microscopic Characteristics And Controlling Factors Of Chang 6 Deepwater Tight Sandstone In Huaqing Area

With the gradual exhaustion of conventional high-permeability reservoirs,low-porosity and low-permeability reservoirs have become their substitute resources and the inevitable trend of petroleum exploration and development has attracted more and more attention from scholars and experts.The Chang 6 deep-water tight sandstone reservoir in Huaqing area of the Ordos Basin has complex diagenesis and strong reservoir heterogeneity,resulting in low single-well production in the study area and severely restricting the stable production cycle of the oilfield.On the basis of fully absorbing previous research results,this paper combines field outcrop profile,core observation,logging data,physical property analysis and other data,using high-pressure mercury intrusion,constant-rate mercury intrusion,low-temperature nitrogen adsorption,nano-CT and other experimental analysis methods to compare The microscopic pore throat characteristics and influencing factors of different types of gravity flow reservoirs in Chang 63 in Huaqing area are studied.This article provides a certain reference for the exploration and development of tight sandstone reservoirs in order to realize the orderly and efficient exploration of tight sandstone reservoirs.And get the following conclusions.(1)The Chang 63 deep-water tight sandstone reservoir in Huaqing area mainly developed three types of gravity flow: slump deposition,clastic flow deposition,and turbidity flow deposition.Turbidite flow deposition was mainly developed in the southwest of the study area,and clastic flow deposition was mainly It grows in the northeast of the study area.The sand body structure types in the study area include continuous stacking type,interval stacking type,lateral pinch-out type,and sand-mud interbedded type.(2)Reservoir lithology is mainly gray-brown,light gray feldspar lithic sandstone and lithic feldspar sandstone,followed by quartz sandstone,lithic sandstone and feldspar sandstone.The average porosity is 10.26%,and the average permeability is0.19×10-3?m2.It belongs to tight sandstone reservoirs with low porosity and ultra-low porosity,ultra-low permeability and ultra-low permeability.(3)The larger the standard deviation of the hole ratio,the smaller the porosity and permeability of the reservoir,and the more complex the pore-throat structure of the reservoir;the pore types are mainly parallel plate-like and fracture-like pores,and the radius is mainly concentrated between 100?m and 200?m.The average value is122.44?m,and the radius of the roar is mainly between 0.2?m and 1.2?m.For the ultra-low permeability reservoirs in the study area,the influence of the throat on the microscopic characteristics of the tight sandstone is greater than that of the pores.(4)The macroscopic factors that affect the microscopic characteristics of the Chang 63 reservoir in Huaqing area are the type of sand body structure,and the microscopic factors include sorting coefficient,roundness,quartz family,feldspar composition,cuttings composition,plastic composition,and miscellaneous base.,Compaction,cementation,and dissolution.The roundness,feldspar composition and dissolution play a constructive role in the development of reservoir pore throats.