DF1-1-D4h Well Borehole Integrity Risk Assessment

In recent years,lots of disasters happened in oil and gas development industry,which draws people's attention to the well integrity study.Though the well integrity is just a newly published concept,the importance behind this word can not be ignored.In this paper,the author analyzed the study work of well integrity both from domestic and foreign experts.Based on this analysis,Aiming at the realities of DFI-lD4h,such as the annulus pressure was abnormal in 2007,the casing pressure gradually increased after the operation of annulus plugging in 2014.According to the "wellbore integrity management solution for in service stage,and the general practice of wellbore integrity at home and abroad.Analysis of wellbore integrity risk assessment for DF1-1D4h,Corrosion of oil casing.Check the structural strength of oil and casing pipe,re accounting the MAASP,and through quantitative risk assessment method.It is concluded that DF1-1D4h is red well.The calculated leakage risk of the well is l7.35,(PI)I well.Should be taken the risk control measures in time.Combining sensitive case analysis,the suggested measures are as follows:The possibility of leakage is significant(4.338),the reliability of key well barrier units needs to be improved,to reduce the possibility of leakage.Refer to the test method of API RP14B,the subsurface safety valve,hydraulic main valves and hydraulic wing valves shall be functional tested annually.The hydraulic main valve and wing valve shall be closed for no more than 5 seconds.It is suggested that tubing hanger and production casing hanger seal be checked regularly,tightness test the tubing hanger and casing hanger seal every year,In order to improve the reliability of key well barrier units.The first stage barrier formed by the Oil sleeve annular space and the plugging liquid in oil pipe has been invalid,It is suggested that reliable reservoir repair method be used to seal reservoir oil and gas.Re-establish a reliable and long-acting first well barrier.Corrosion analysis of oil casing pipe in well,it is found that the upper production casing is made of 1Cr material,Regular monitoring of A and B annular space and finding that collusion due to corrosion perforation of the production casing requires immediate control measures.In order to maintain the continuous monitoring of the A and B annular spaces in the DFI-lD4h,the following systems need to be established in the oilfield:Improve the belt pressure management process of the annulus from the aspects of monitoring,emergency and personnel responsibility;Establish an annular space early warning process,monitoring the annular space pressure maintained in the range of MAASP.According to calculation,the MAASP of A and B annular spaces were 14.24MPa and 9.52 MPa.When the annular space pressure approaches 80%of the MAASP,it is recommended that the pressure be released immediately.