Evaluation Of E_2-3z₃ Reservoir In Huomatu Anticlinal Zone In The Southern Margin Of Junggar Basin

Junggar basin is located in the north of the Xinjiang Uygur Autonomous Region, It is lacated in the south of Tianshan Mountain,the northwest of Zaire mountain and Hala’alat mountain and the northeast of Qinggil mountain and Kelameili mountain,The distance from east to the west is about 700 km long,The distance from north to the south is about 320 km wide,The area of basin is 13 X 104 km2.Huomatu anticlinal zone is located in the he middle of the southern margin in junggar basin,which is lacated in the west of Sikeshu sag, the north of Changji sag, in the south of Qigu fault-fold structural belt and the east of Fukang fault zone,The anticlinal zone is E-W. The distance from north to the south is about 26 km wide,The distance from east to the west is about 176 km long,The area of basin is 7545 km2. Main distribution from the west to the east are Anjihai anticline, Huoerguosi anticline, Manasi anticline, Tugulu anticline and Hutubi anticline. The thickest sedimentary strata is up to 15000 meters,and developed many sets of source-reservoir-seal assemblage,the resources’potential is tremendous.In the early 90s,petroleum geologists has carried out tertiary Miocene layer drilling work in the area, although there are different levels of oil and gas shows and low yield oil flow,failed to obtain a breakthrough. With the deep-going of exploration, in 1996 and 2007, respectively, petroleum geologists found Hutubi gas field and Mahe gas field in Hutubi and Manasi anticline,However,Anjihai anticline, Huoerguosi anticline, Tugulu anticline,which belong to Huomatu anticlinal zone,found prolific hydrocarbon flow,the subsequent evaluation of exploration were failed. Studies have shown that in addition to the structural factors controlling the distribution of oil and gas reservoir layer.the development characteristics and the distribution of reservoir is also one of the major factors. As the main oil and gas reservoir unit,the reservoir distribution rule and prediction of the Paleogene E 1.2z3 are particularly important.Under the guidance of sedimentology and reservoir geology theories, taking advantage of cast thin section, scanning electron microscopy, mereury injection, X-ray diffraction and other geochemistry data, combining drilling core and logging resources,this paper deeply researched the reservoir lithology features, physical property, pore textures features, the diagenesis, the controlling factors of physical property in the Huomatu anticlinal zone,in order to make clear the regularities of reservoir development and the prediction of favourable reservoir,providing certain theoretical support for the favourable zone of late oil and gas exploration.First of all, from the perspective of the reservoir petrology characteristics, mastering the clastic rock composition,interstitial fillings and strucrure,in order to analyse the difference of rock composition of different anticline in study area,Clarifying the regularities of distribution of porosity and permeability,Clarifying the features between lithology and physical property,lithology and oil content. Building porosity model through core analysis data and density logging curve,drawing porosity and permeability contour map of the study area. make clearing the types pore and throat and pore structure characteristics,Then analysing the characteristics of diagenesis and the distribution of diagenetic facies in the study area. Finally, confirming the reservoir classification standard through the analysis of the control factors of reservoir physical properties,and evaluating the favourable reservoir,summarizing regularities of reservoir development.Through the study, the understanding of Huomatu anticlinal zone mainly includes the following points:(1) The reservoir is mainly composed of lithic feldspathic sandstone,feldspathic lithic sandstone and lithic sandstone secondly, different rock composition in different anticline,but rock composition maturity is medium; and cement are calcite, siliceous minerals and anhydrite, of which content are between 3% and 8% on average in different anticline, Cement content is low. Sandstone sorting is generally medium to good, the structure of the sandstone maturity is higher. Reservoir as a whole is low cementing material content,medium compositional maturity and high textural maturity.(2) The pore types of E1-2Z3 reservoir are mainly intergranular pore, residual intergranular pore and contains a small amount of dissolution pores in study area; just Hutubi anticline contain most dissolution pore,which is mainly intergranular solution pores, intergranular pore. The types of throat are mainly necking throat,followed by the pore narrow throat, flake throat. The pore-structure are mainly type Ⅲ, medium pore and medium-thin throat.type Ⅱ, medium pore and medium throat,followed by the type I, macroporous and coarse throat,which is mainly developed in manasi anticline.(3) The diagenesis of E1-2z3 reservoir are mainly compaction, cementation and dissolution in Huomatu anticlinal zone. According to authigenic mineral assemblages, organic thermal maturity indicators and other characteristics,combined with observing flakes in the study area, the diagenesis is divided into the stage A1 of middle diagenesis phase and the stage A2 of diagenesis in which Hutubi anticline is the deeper depth..Reservoir mainly developed the phase of strong compaction and weak cementation dissolution and the phase of medium compaction and weak cementation dissolution,and each anticline diagenetic phase is different.(4) By controlling the sandstone clastic composition, particle size and so on the deposition controls the reservoir properties.In a word, the physical properties of underwater distributary channel sands is the best,and bay sands between distributary channels is worse physical properties because of low compositional maturity.Meanwhile,in the same source direction and the same depositional environment, there are the different sand body types and physical properties; besides,the different rock maturity, their physical properties are different.(5) The control of diagenesis on reservoir physical properties is manifested in different anticline and different burial depth,which the type and intensity of their sufferred diagenesis have the significant differences.Vertically,with the increaseof buried depth, compation strength also increases gradually.Overall,the study area has the greatest effect in the compression ability,and the average compacting hole volume reduction is 21.25%; Cementation reduces reservoir property,and cementation hole volume reduction of 2.96% on average; Dissolution improve reservoir,and the average corrosion increases the value of 2.21%.(6) The favourable facies of E1-2z3 reservoir are mainly underwater distributary channel, mouth bar,distal bar of meandering river and braid river delta front,the distribution of reservoirs is in accord with sedimentary facies. Based on analysis of the reservoir property development controlling factors in the study area, in combination with pore types, the reservoir in the study area can be divided into five categories. The medium-high porosity and medium-high permeability reservoir is developed in the area of well Mana 001 and well Mana 001. The medium porosity and medium permeability reservoir is developed in the area of well Huo 001,well Hu 001,well Hu 002. The medium-low porosity and medium-low permeability reservoir is developed in Huoerguosi anticline, Anjihai anticline, Tugulu anticline and the area of well Hu 2, well Dafengl in Hutubi anticline.Thelow porosity and low permeability reservoir is less developed in the study area, only developed well Tugu 1,well Tudong 1,well An 6 and well Huxi 1.