Study On Antileakage Cement Slurry For Porosity-fracture Type Leak Formation

In an oilfield of QK construction and BS block have the problem of leakage risk of the pore and crack co-existence in well completion and cementing process.In order to solve the problems,paramount consideration the leak-proof plugging evaluation device for cement slurry,and designs a simulation test device for the co-existence of pores and cracks,then proposes an evaluation method based on the device.Researched two kinds of density leak-proof cement slurry,using this device to evaluate the leak-proof and plugging capacity of two kinds of density leak-proof cement slurry.Test the comprehensive application performance of cement slurry.And field trial application for a well.The work carried out by the thesis and the research results are as follows:(1)Based on the existing leakage prevention and plugging device for cement slurry,this paper designs a new leak-proof leakage performance evaluation device for cement slurry based on actual leakage conditions of the formation.In this experimental device,multiple fracture channel models and pore crack co-existence channel models.And the high-precision data measurement system is introduced to record the entire process of leak detection.The main performance parameters:diameter 0.5mm and 1.0mm,cracks 6.0mm×0.5mm and 6.0mm×1.0mm,accuracy of data collection 0.01g,cement slurry volume 485ml,working pressure 0?10.0MPa,highest temperature 150?.(2)Based on the experimental results of simulated leakage of pores,cracks,and pores cracks co-existence,the paper proposes an evaluation method for the leakage prevention and plugging capacity of cement slurry based on research devices.The evaluation methodology considers the evaluation index and the sequence factors.The comprehensive evaluation of the four indicators of quantity,pressure plugging capacity,cement slurry leakage weight,loss time and loss rate.(3)The paper analyzes the performance of leak-proof and plugging materials,choose modified fibers and rubber particles as leak-proof materials for experiments.Research a conventional density leak-proof cement slurry system and used the new evaluation device to evaluate leak-proof and plugging performance of leak-proof cement slurry under different leakage media and different temperature conditions.Test and analyze the conventional performance of leak-proof cement slurry.Experimental results shows that the amount of modified fiber 0?0.6%compounded with 1.8%of rubber particles,and the loss weight of cement slurry is less than 100g,the loading capacity of the plugging layer is greater than 7.0MPa.Thickening time of conventional density cement slurry is 134min?170min,thickening curve is stable and thickening time adjustable.One days cement stone compressive strength is 20.93MPa?22.46MPa and flexural strength is 5.18MPa?6.45MPa.(4)The paper used modified fiber and rubber particles to study light-weight leak-proof cement slurry,and used the new evaluation device to evaluate leak-proof and plugging capacity of light-weight leak-proof cement slurry under different leakage media and different temperature conditions.Test and analyze conventional performance of light-weight leak-proof cement slurry.Experimental results shows that the amount of modified fiber 0-0.6%compounded with 1.3%of rubber particles,the loss of cement slurry is less than 100g,the sealing layer pressure capacity are greater than 7.0MPa.Low-density slurry thickening time is 345min?379min,thickening curve is stable and thickening time adjustable.One days cement stone compressive strength is 9.21 MPa-12.52MPa and flexural strength is 2.39MPa?3.25MPa.The results of well cementing test in the BS3 tailings show that the leakage prevention and plugging effect of the low density and conventional density leak-proof cement slurry is good,and no well leakage occurs during the cementing construction.The 48h well logging results show that the cementing quality is good.