| Sulige gas field is a typical "four low" gas reservoir with low permeability,low pressure,low abundance and medium and low yield.It is low in bearing capacity and easy to leak in the process of cementing.Low density cement slurry technology is one of the most effective solutions to the problems of low pressure and leaky formations and long cementing in the cementing area.But the commonly used low density cement slurry has the disadvantages of unstable system density,poor compatibility with drilling fluid,complex composition of admixtures and large amount of additive,which can not meet the requirements of cementing quality,and the cementing cost is high.At the same time,in the process of drilling,a large number of waste drilling fluid is usually produced,once the improper treatment will bring huge environmental pollution,and in recent years our country's environmental awareness is increasing,the problem of waste drilling fluid treatment needs to be solved.MTC technology is an effective solution to this problem.but the strength of MTC solidified body is low under low temperature and low density,and its brittleness is large and easy to crack,which greatly restricts its popularization and application.In this paper,the paper aims at many technical problems,such as easy hole leakage,high cost of conventional low density cement slurry,strict environmental protection requirements and large brittleness of conventional MTC solidified body during the injection of low pressure leaking gas field in Sulige gas field.The slag and slag suitable for the drilling fluid system are selected and selected in combination with the specific working conditions of the Sulige gas field.Auxiliary treatment agent.S105 grade slag produced in Jiahua cement plant is used as a cementitious material,with pumice powder as active modification material,basalt fiber as physical modification material.CMC as suspension agent,JQY:JSY:JTY=3:2:1 as compound activator.S as diluent and WRJ-B as decontamination agent,and a set of suitable for Sulige gas field at the end.The low cost curing fluid system with better cost,better mechanical properties and disposal of waste drilling fluid has been successfully applied in the field.The compressive strength of the solidified body 1d,3d and 7d increased by 167%,74%and 29.9%respectively at the curing temperature of 50 ?,and the ultimate strain of the modified solidified body was increased by 50.5%,and the young's modulus decreased by 43.8%.It solved the problem of low early strength under low temperature and low density and the large brittleness of the solidified body.The cost saving is 343 thousand and 200 yuan,which has huge economic benefits.Through the analysis of XRD,SEM,TG and CT,the addition of pumice powder can fill the pores in the slag hardened body on the one hand,make the larger void in the body change to the harmless capillary pore,increase the solid content in the unit volume,make the matrix more compact and improve the mechanical properties;on the other hand,SiO2 in pumice powder.Al2O3 and Ca(OH)2,one of the products,reacted with volcanic ash to generate more fiber or rod like I C-S-H gel and C-A-H gel in the three-dimensional network structure,which consumed Ca(OH)2 in the slag hydrated slurry,and increased the gel quantity and improved the mechanical properties of the solidified body.Basalt fiber improves the mechanical properties of the solidified body through "bridging”,"crack deflection","fiber pull-out" and "filling".It has little effect on the hydration of slag,and only acts as a physical admixture to enhance and toughen the slag solidified body. |
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