The evaluation of permeability in reservoir assessment is a complex problem. Thus, it is difficult to perform direct evaluation permeability with conventional well-logging methods. Considering that reservoir permeabil...The evaluation of permeability in reservoir assessment is a complex problem. Thus, it is difficult to perform direct evaluation permeability with conventional well-logging methods. Considering that reservoir permeability significantly affects mud invasion during drilling, we derive a mathematical model to assess the reservoir permeability based on mud invasion. A numerical model is first used to simulate the process of mud invasion and mud cake growth. Then, based on Darcy＇s law, an approximation is derived to associate the depth of mud invasion with reservoir permeability. A mathematical model is constructed to evaluate the reservoir permeability as a function of the mud invasion depth in time-lapse logging. Sensitivity analyses of the reservoir porosity, permeability, and water saturation are performed, and the results suggest that the proposed model and method are well suited for oil layers or oil-water layers of low porosity and low permeability. Numerical simulations using field logging and coring data suggest that the evaluated and assumed permeability data agree, validating the proposed model and method.展开更多
A temperature-sensitive mud cake remover(G315)was developed using ethyl lactate as the primary component.Based on this,a temperature-sensitive acidic completion fluid(CF-G315)was formulated.Core evaluation tests,mud c...A temperature-sensitive mud cake remover(G315)was developed using ethyl lactate as the primary component.Based on this,a temperature-sensitive acidic completion fluid(CF-G315)was formulated.Core evaluation tests,mud cake dissolution tests and corrosion tests were conducted to analyze the mud cake removal performance of G315,the removal efficiency of CF-G315,and its ability to modify the near-wellbore reservoirs,corrosion to casing and hydrolysis performance.Results indicate that ethyl lactate in G315 exhibits weak acidity at room temperature and decomposes into lactic acid under high temperatures.The lactic acid reacts with the calcium carbonate in the mud cake,generating bubbles that dislodge the mud cake and form soluble salts that are subsequently removed by fluid flow,thereby ensuring effective mud cake clearance.CF-G315 removes mud cake efficiently and enhances near-wellbore reservoir permeability.It demonstrates low corrosivity and environmental compatibility,contributing to equipment safety,simplified operational procedures and reduced operational risks.CF-G315 is promising for application in scenarios such as horizontal wells,open-hole completions and gravel pack completions.展开更多
基金financially supported by the Open Fund(No.PLC201103) of the State Key Laboratory of Oil and Gas Reservoir Geology and Exploration(Chengdu University of Technology)Open Fund(No.PRP/OPEN-1302) of the State Key Laboratory of Petroleum Resources and Prospecting(China University of Petroleum,Beijing)+2 种基金PetroChina Innovation Foundation(No.2015D-5006-0304)National Natural Science Foundation of China(No.41304078)Sinopec Foundation(No.P14136)
文摘The evaluation of permeability in reservoir assessment is a complex problem. Thus, it is difficult to perform direct evaluation permeability with conventional well-logging methods. Considering that reservoir permeability significantly affects mud invasion during drilling, we derive a mathematical model to assess the reservoir permeability based on mud invasion. A numerical model is first used to simulate the process of mud invasion and mud cake growth. Then, based on Darcy＇s law, an approximation is derived to associate the depth of mud invasion with reservoir permeability. A mathematical model is constructed to evaluate the reservoir permeability as a function of the mud invasion depth in time-lapse logging. Sensitivity analyses of the reservoir porosity, permeability, and water saturation are performed, and the results suggest that the proposed model and method are well suited for oil layers or oil-water layers of low porosity and low permeability. Numerical simulations using field logging and coring data suggest that the evaluated and assumed permeability data agree, validating the proposed model and method.
基金Supported by National Natural Science Foundation of China(52404010).
文摘A temperature-sensitive mud cake remover(G315)was developed using ethyl lactate as the primary component.Based on this,a temperature-sensitive acidic completion fluid(CF-G315)was formulated.Core evaluation tests,mud cake dissolution tests and corrosion tests were conducted to analyze the mud cake removal performance of G315,the removal efficiency of CF-G315,and its ability to modify the near-wellbore reservoirs,corrosion to casing and hydrolysis performance.Results indicate that ethyl lactate in G315 exhibits weak acidity at room temperature and decomposes into lactic acid under high temperatures.The lactic acid reacts with the calcium carbonate in the mud cake,generating bubbles that dislodge the mud cake and form soluble salts that are subsequently removed by fluid flow,thereby ensuring effective mud cake clearance.CF-G315 removes mud cake efficiently and enhances near-wellbore reservoir permeability.It demonstrates low corrosivity and environmental compatibility,contributing to equipment safety,simplified operational procedures and reduced operational risks.CF-G315 is promising for application in scenarios such as horizontal wells,open-hole completions and gravel pack completions.
