Study On The Characteristics Of Salt Shale Reservoir In Qianjiang Formation In Qianjiang Sag

Due to the decline of conventional oil and gas production in the world,unconventional oil and gas resources are becoming more and more important.As conventional oil and gas resources,one of the important resources of shale oil,has a wide oil-bearing area,abundant resources,the production characteristics of long service life and sTab.production,has now become a new bright spot of global oil and gas exploration and development,with further exploration and development of broad prospects.Shale oil refers to the accumulation of petroleum accumulation in the rich organic mud shale and its siltstone,sandstone and carbonate interlayer.Qianjiang Sag of Jianghan basin are widely distributed between the thickness of the larger continental salt lake salt mud shale,its organic matter content is rich,has a certain maturity,the thickness of the single rhythm is larger and has a certain depth,in line with the shale oil accumulation of petroleum geological conditions,to study its inter salt reservoir may take the lead to achieve the breakthrough of continental shale oil exploration in our country,open up a new field of unconventional oil and gas exploration in China.However due to the former Qianjiang sag of Jianghan basin exploration and research are based on conventional thoughts as the instruction,studies of inter salt shale oil reservoir is still relatively weak,lack of strong operational facies classification scheme,inter salt shale oil reservoir space,reservoir structure is not yet clear,and the salt formation between rhythm is numerous,the good and bad are intermingled,so have not been established inter salt shale oil reservoir effective salt system evaluation method.This thesis Qianjiang Sag of Jianghan Basin the 10th rhythm of Eq3⁴ and the 5th rhythm of middle Eq4⁰ inter salt shale as the research object,based on the geological data in the study area of a large number of collection and sorting,and make full use of drilling,logging,well logging and slice analysis,scanning electron microscopy?SEM?,organic geochemistry and so on a variety of analysis methods,in-depth and systematically studied the shale rhythm between the two sets of inter salt shale lithological facies,puts forward more meets the needs of the current exploration facies classification scheme;The reservoir conditions?pore classification,porosity,permeability and pore throat size?were studied.The reservoir type of the shale rhythm between the two sets of inter salt shale is divided;Studied oil?organic matter abundance,organic matter type,maturity,and pyrolysis free hydrocarbon?,analysis the status of inter salt shale oil,and eventually explore shale oil reservoir factors influencing the control salt and preliminary evaluation method.Main achievements and understanding.To elaborate inter salt shale facies of the 10th rhythm of Eq3⁴ and the 5th rhythm of middle Eq4⁰ in the study area,on the basis of core macroscopic structure,organic matter content and rock mineral composition,in order to"four components of three yuan"as the principle of classification,the inter salt shale formations of the 10th rhythm of Eq3⁴ in the study area is divided into four kinds of lithofacies:carbon-rich lamellar argillaceous dolomite facies,carbon-rich lamellar dolomitic mudstone facies,carbon-rich lamellar calcite mudstone facies,carbon-rich calcium-glauber filling lamellar dolomitic mudstone facies;the inter salt shale formations of the 5th rhythm of middle Eq4⁰ in the study area is divided into seven kinds of lithofacies:carbon massive dolomitic mudstone facies,carbon lamellar argillaceous dolomite facies,carbon flaggy calcite mudstone facies,carbon anhydrite filling massive calcite mudstone facies,carbon massive argillaceous dolomite facies,carbon anhydrite filling massive argillaceous dolomite facies and carbon-poor anhydrite filling massive dolomitic mudstone facies.The plane distribution of different facies is determined by combining logging interpretation results.Among them,there is the most favorable inter salt shale facies carbon-rich lamellar argillaceous dolomite facies.By studying the reservoir space of shale reservoir,five types of shale reservoir space are identified:intercrystalline pore,intergranular pores,dissolved pore,holes and different causes of cracks.Analysis its origin,size,distribution and effectiveness,the inter salt shale pore types of the 10th rhythm of Eq3⁴ is mainly intergranular pore and dissolution pore,and a large number of cracks development,formed the pore-crack system,the porosity of 3.52%³2.06%,average 21.8%,permeability is0.01mD³.53mD,with an average of 0.98 mD;The inter salt shale pore types of the 5th rhythm of middle Eq4⁰ is the intracrystalline solution pores,intergranular hole,hole and followed by carbonate rocks bedding joint,crack is less,and anhydrite,filling a maximum porosity is 12.4%,the minimum value is 0.7%,the average is 7.69%,high permeability of 3.07 mD,lowest 0.0525 mD,an average of about 0.38 mD.It's a synthetic analysis,and the inter salt shale reservoir of the 10th rhythm of Eq3⁴ is the middle hole low permeability carbon-rich pore-fracture type reservoir,is better than low porosity and low permeability carbon porosity type reservoir of the 5th rhythm of middle Eq4⁰,The lower limit of the mobile hole throat is 40nm.Through the analysis of oil-bearing indexes including the organic matter abundance,organic matter type,maturity,and pyrolysis free hydrocarbon of the inter salt shale in the 10th rhythm of Eq3⁴ and the 5th rhythm of middle Eq4⁰ of Qianjian Sag,the carbon content of the inter salt shale of the 10th rhythm of Eq3⁴ was found to be between 0.35%and 6.38%,with an average content of 3.35%,and organic matter type I and type II kerogen.Vitrinite reflectance Ro distribution range of 0.4%⁰.8%,the maturity of unripe-low-mature oil amount of latent value distribution of S₁+S₂ range between 1.9 mg/g⁴3.39 mg/g,an average of 22.61 mg/g,show the inter salt shale reservoir in the 10th rhythm of Eq3⁴ with high oil content and the biggest oil potential,is rich oil reservoir;Organic carbon?TOC?values the inter salt shale in the 5th rhythm of middle Eq4⁰ range between 0.2%¹.57%,the average content of 0.72%,organic matter type mainly for type II kerogen,the 5th rhythm of middle Eq4⁰ depth is larger,Ro of the 5th rhythm of middle Eq4⁰ maximum is 1,maturity,amount of oil potential of value distribution of S₁+S₂ range between 0.37 mg/g¹0.87 mg/g,the average is 4.58mg/g,shown medium level of the oil content of shale reservoirs,a the 10th rhythm of Eq3⁴ shale reservoirs between salt oil content is low,for medium reservoir.Through explore the occurrence state of the inter salt shale oil,think the Qianjiang Formation of Qianjiang Sag shale oil occurrence state has a free,dissolve or adsorption of three kinds of state and is given priority to with free,adsorption state times,contains a small amount of dissolved shale oil.The free hydrocarbon mainly exists in the inorganic mineral grain layer,matrix pore and fracture system.It is found that the mineral composition,compaction,metasomatism,recrystallization and dissolution of rocks affect the physical properties of the inter salt shale reservoir.According to shale oil accumulation conditions,shale oil reservoirs at home and abroad for reference,the evaluation standard,lithologic facies,lubricity,reservoir conditions,and the thickness of the comprehensive comparative evaluation of the 10th rhythm of Eq3⁴ and the 5th rhythm of middle Eq4⁰ in inter salt shale reservoir.