Research On Drilling And Completion Fluid Optimization Technology In Bozhong 34-9 Oilfield

In the process of drilling and completion of Bozhong 34-9 oilfield,it is inevitable to cause damage to the reservoir.In order to effectively protect the reservoir,this paper has carried out a sensitivity evaluation of the reservoir core of Bozhong 34-9 oilfield and discussed the mechanism of reservoir damage;Based on the analysis of the complex situation of drilling in Bozhong 34-9 oilfield,in order to meet the requirements of drilling safety and reservoir protection in Bozhong 34-9 oilfield,optimization of the drilling and completion fluid system in Bozhong 34-9 oilfield.The core sensitivity of the Bozhong 34-9 oilfield reservoir was evaluated through core flow experiments.The results show that:(1)The Bozhong 34-9 oilfield reservoir is moderately weak and sensitive,with a critical flow rate of 1.00 m L/min;(2)The reservoir in Bozhong 34-9 oil field is moderately weak and water-sensitive,and the critical salinity is 4694 mg / L ～ 9388 mg / L;(3)The reservoir in Bozhong 34-9 oilfield is not acid sensitive;(4)Bohai The reservoirs in Zhong34-9 oilfield are moderately weak and alkali-sensitive,with a critical p H of 10.(5)The reservoirs in Bozhong 34-9 oilfield are moderately strong and stress-sensitive,with a critical stress of 3.5 MPa.The formulation of PEC drilling fluid in the 12-1/4 "well section of Bozhong 34-9 Oilfield was optimized.The optimized PEC drilling fluid formulation reduced the type and amount of plugging agent,and the optimized PEC drilling fluid had better suppression.Performance,temperature resistance and anti-pollution performance,at the same time,its rheological properties,filtration performance and plugging performance are basically equivalent to the PEC drilling fluid before optimization.Optimized the formulation of PEM drilling fluid in the 8-1/2 "section of directional wells in Bozhong 34-9 Oilfield,the optimized PEM drilling fluid has a lower filtration loss;the types of plugging agents in the optimized PEM drilling fluid formulation and their additions The amount of PEM drilling fluid is reduced,and the optimized PEM drilling fluid has good inhibition,temperature resistance and anti-pollution properties.At the same time,its rheological performance,filtration loss performance,lubricity and plugging performance are basically equivalent to those of PEM drilling fluid before optimization.The protection ability of the later PEM drilling fluid reservoir is better than that of the PEM drilling fluid before optimization.Optimized the formulation of EZFLOW drilling fluid for horizontal wells in Bozhong 34-9 Oilfield.The optimized EZFLOW drilling fluid has better suppression and anti-pollution performance,and its rheological performance,filtration loss performance,lubricity and plugging performance are better than PRD.The drilling fluid system,and the optimized EZFLOW drilling fluid is better than the PRD drilling fluid system in its ability to directly drain back to the reservoir under the condition of no glue breaking treatment.The invisible acid completion fluid system suitable for the Bozhong 34-9 oilfield was optimized.The invisible acid completion fluid was injected into the optimized PEM drilling fluid-contaminated cores,and the core permeability recovery values were all greater than 85%.The optimized EZFLOW drilling was started.After the core contaminated with liquid was treated with a stealth acid completion fluid,the core permeability recovery value was 94.31%.The preferred stealth acid completion fluid system has better reservoir protection capabilities.