Analysis On The Mechanism Of Low Production And Low Efficiency Of Shale Oil And Research On Potential Tapping Countermeasures

Domestic shale oil development has been paid more and more attention,but shale oil reservoirs have the characteristics of low permeability,strong heterogeneity and complex seepage medium,resulting in low production and low efficiency,which greatly restricts the expansion of shale oil development scale.The study of low production and low efficiency seepage mechanism and main control factors is one of the core problems.According to the typical shale reservoir in Ordos,the development dynamic analysis is carried out,the seepage mechanism of low-yield and low-efficiency wells was analyzed,the typical models of three types of wells are established,and three kinds of adjustment and potential tapping countermeasures are designed.Key findings and conclusions:(1)The application verifies the dynamic analysis and mechanism evaluation methods of low-yield and low-efficiency wells.Using Saphir and professional low permeability well test analysis software to carry out secondary well-testing interpretation of single wells,put forward the concept of inner and outer zones of oil and water wells,the geological characteristic parameters of typical low permeability reservoirs are quantified,and the heterogeneity and seepage capacity of oil and water wells are clarified.Inverse calculation of interwell permeability by productivity and analysis of hydraulic connectivity between injection and production wells;using the reservoir engineering diagnostic curve analysis method,the energy supply and the corresponding relationship between injection and production are analyzed.The channeling flow channel analysis method is used to quantify the heterogeneity between wells,and the reservoir heterogeneity characteristics and channeling flow channel geometric parameters are clarified.(2)The seepage mechanism and main control factors of three types of low-yield and low-efficiency wells are clarified.The main control factor of low-yield wells is reservoir physical property,which has the problems of ineffective water injection,poor near-well transformation effect and insufficient energy supplement.The main controlling factor of low efficiency well is channeling channel,and there is channeling problem of injected water.The main controlling factors of low-yield and low-efficiency wells are reservoir physical properties and channeling channels.There are problems of ineffective water injection,insufficient energy supplement and channeling of injected water.(3)Three types of potential tapping countermeasures for low-yield and lowefficiency wells are preliminarily designed.The geological model and reservoir numerical model of typical shale oil well areas are established.For low-yield wells,it is recommended to carry out pressure drive water injection or fracturing stimulation technology.For low-efficiency wells,it is recommended to carry out unstable water injection stimulation and water control technology countermeasures.For low-yield and low-efficiency wells,it is recommended to carry out joint fracturing and unstable water injection adjustment countermeasures.The stimulation adjustment countermeasures of fracturing to improve reservoir physical properties are given priority,and then the adjustment countermeasures of strengthening water control are carried out.