Geological Features Of SQ Buried Hill Underground Gas Storage In Huabei Oilfield

The construction of gas storage started relatively late in China,the geological conditions of oil and gas reservoir is complicated for rebuilding,and generally buried deep,all of them seriously impede the construction and the use of gas storage.Therefore,carrying out studies for the geologic features aimed at rebuilding exhausted gas pools into gas storages is an important issue in the business development of gas storage in our country.This study described the general geology of the gas reservoir of SQ buride hill in Huabei Oilfield,the generalization of the gas reservoir,formation characteristics,structural characteristics,status of reservoirs and gas reservoirs and other content of the depleted reservoirs has been depth analysised.Based on the studies,theory and method of the gas storage geological evaluation techniques,and using logging data and seismic data,expanding fine interpretation and reservoir prediction,analysising the seal conditions of the depleted gas reservoir,determining the type and characteristics of gas reservoir.Following major conclusions are obtained by researching:(1)Cap rock of SQ buried-hill gas reservoir is a set of sequentially deposited stratum and parallelly covers on the Ordovician.It is the dense terrane mixed up with mudstone and coal seam,and is good cap rock.On the stratum which covers on the buried hill,there is a series of layerbased on the mud rocks,mingled with coal and rock strata,which forms the complex cap rock,and furtherly strengthening its closure.(2)The computational solution of SQ buried-hill control the fault's elements and reservoir andcap rock's parameter shows that fault in the buried hill is all equipped with good sealing ability of stratum.Smudge analysis method of materials on the fault surface is used to examine the closure of fault at the edge of SQ buried hill.(3)Large crevice and hole in SQ is not developed and shows relatively strong reservoir heterogeneity.Six reaction belts,including air-slake leaching,breakage,corrosion along layer,horizontal corrosion,vertical leaching and high pore,are interwoven and composed the reservoir body of SQ buried hill.(4)Reservoir space of SQ buried-hill Ordovician is a type of micro-fracture porosity,and reservoir is also the type of micro-fracture porosity with low porosity and low permeability.In the exploitation process of SQ carbonate gas reservoir over many years,damage caused by water invasion in the flooded region and gas/water transition zone is relatively severe,which affects the displacement and expansion result of gas injection in the process of reconstruction of gas storage.(5)In the design of construction of underground gas storage,it is necessary to consider the influence of relative interlayer on the building of storage.By the time of well drilling,it should pierce the relative interlayer as far as possible,to inject and produce gas of massive oil-gas reservoir in an integral and even way.(6)After several factors like geographic position and geological conditions are comprehensively analyzed,the closure of layer of SQ buried-hill gas reservoir are seemed to be fine,and reservoir physical property can meet the injection and production requirements in the late period,and consequently satisfies the demand for building underground gas storage.