| Volcanic reservoirs are important new areas of oil and gas exploration in recent years,But the facror of volcanic reservoirs are extremely complex,which seriously hindered volcanic oil and gas exploration.This paper studied the Carboniferous volcanic rocks in the Shixi Oilfield,Junggar Basin.Based on the data of drilling,logging,oil testing,core observation,imaging logging and production data,under the guidance of petrology,petroleum geology,structural geology theory,Carboniferous volcanic reservoir in the ShiXi oilfield's lithologic facies,rock facies,tectonic action,weathering and so on in ShiXi oilfield.And discusses its impact on the reservoir,and finally get clear the reservoir favorable area.The main conclusions are as follows:(1)Identification of volcanic lithology based on conventional logging data to establish GR-CNL?GR-DEN crossplot.The main reservoir rocks in the study area are aggregated rocks,striped lava,brecciated lava and dense tuff.The reservoir space is dominated by primary pores,dissolved holes and fractures,the pore structure is thin pore,the carboniferous reservoir is a typical pore fractured reservoir.According to lithology and phase sequence characteristics,The lithology(lithofacies)of single well and connecting-well proflie is analyzed,the vertical and horizontal distribution characteristics of reservoir lithology(lithofacies)are clarified.(2)Lithological physical property analysis and production,the reservoirs of aggregated rocks are the best in the study area(Porosity 9.0%?18.0%,permeability 0.1?2.51×10-3?m2),followed by lava.Aggregate rocks developed dissolved pores and intergranular pore,good weathering ability,Crack development density.Volcanic lava developed secondary pore,which has better permeability,good weathering ability,large crack density.The comprehensive analysis shows that lithology is one of the factors affecting the reservoir.(3)Carboniferous volcanic reservoirs develop fracture,the type of fracture is mainly Structural joints and weathering joints,which have high angle and straight split,and medium development scale,larger width,small density,large spacing.There were four periods during the development of fractures.Fractures development is mainly affected by tectonism and weathering,which close to the top of the Carboniferous 200m range and the fault.So on the high point of structure,fractures are more frequent.The plane is mainly distributed in the line of SHI001-SH1034-SH1109-SH1011 area.Combining production test data shows that fractures can effectively improve reservoir property.(4)Carboniferous volcanic reservoirs suffered strong weathering and denudation,located on the ancient high ground part of the residual hill,which was subjected to weathering leaching strong,fractures are also the most developed,which is conducive to the formation of effective reservoirs.Strong weathering zone porosity between 8 to 30%.It is better to study the seepage characteristics of reservoirs below 200m from the top of Carboniferous is better than others,weathering is an important factor affecting reservoirs.(5)Combined with lithology(lithofacies),tectonic action,weathering and other conditions,the reservoir evaluation system of the study area was established,the dominant area of volcanic reservoirs is divided,determine the favorable reservoir range.The results show that the reservoir I is only developed in the B section,mainly distributed in the area of SH1125-SH1120-SH1117-SH1203-SH1041?Grade ? and ? reservoirs are distributed in three sections?... |
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