Research On The Geological Characteristics And Productivity Control Factors Of Heshui Nanchang 6 Reservoir

After the successful exploitation of shale gas,the tight oil has become the largest exploration and development hot spot in the field of unconventional oil and gas.Because of its poor physical property and percolation capacity,the single well has no natural productivity,thus commercial oil and gas flow must be obtained through fracturing and other measures to increase production.Chang6 tight sand reservoir of south area of Heshui in the Ordos basin has some problems in mining,such as its good sign of oil and gas connectted with poor oil testing effect and it has large productivity differences.Firstly,in this article,the author researches and depicts the sedimentary facies and the stacking patterns of sand body by core observation and analysis of different area data.Secondly,the author analyzes the characteristics and classified different types of the reservoir through the techniques of the casting thin slice,argon ion polishing+field emission scanning electron microscope,NMR and high pressure mercury test.Finally,the author analyzes the control factors of production capacity by fracturing fluid damage experiment and development data.The main research findings are as follows:(1)The sedmentary environment of Chang6 reservoir is gravity flow in semi-deep to deep lake,sand body types are mainly sandy debris flow,turbidite and slump rock.Based on the four single sand body categories including box shape,campaniform,infundibuliform and finger,and combined with sand body thickness,loggong curve shaps and thickness of muddy intercalation,the author finally sets up vertical feature division standard of sand body.(2)The main lithology is fine grained feldspathic lithic sandstone and lithic feldspar sandstone,medium separation,sub prism of grinding roundness,low-medium maturity degree,fillings are mainly water mica and carbonate cementation,high local content of chlorite.The average porosity is 8.29%,and the average permeability is 0.10mD,and fracture developed in partial layer.(3)The pore types of Chang6 reservoir are simple,mainly inclouding dissolved pores,followed by intergranular residual holes.Mercury injection test indicates that the average pore radius of Chang6 reservoir is 124.36?m,the average throat radius is 0.25?m,the maximum connected pore radius is 0.25?m-1.03?m,the average median radius is 0.08?m.The shape of NMR T2 spectrum of Chang6 reservior presents double peaks,the average value of movable fluid saturation is 24.83%.There are three types of reservoirs in the study area,and the most developed type is ?.(4)The article studied the geological and engineering factors that control production capacity.It is considered that the vertical features of sand body,oil saturation and argillaceous content are closely related to productivity.The fracturing fluid system and the use of new technology is the key factors affecting the fracturing production capacity.Through this research,we clarify the reservoir characteristics and control factors of fracturing production capacity in the south area of Heshui Chang6 tight oil.It provides an important basis for the selection of high quality reservoir,design of later fracturing layer and scheme design.Moreover,it is of great reference significance for the development of other block area of tight oil.