Study On High Temperature Solidification Characteristics Of Portland Cement And Leak Plugging Material Of Deep Hole Wall

In the exploration of deep mineral resources,the borehole temperature is high?up to 100-150??,the formation temperature is high,the fracture pressure is low,the borehole wall is prone to collapse,the fractures are developed,and the loss is serious.It is one of the key technical problems in the exploration of deep mineral resources that the protection wall of the borehole in high temperature.Cement and other inorganic cementitious materials,as important wall protection and plugging materials,play an important role in solving the technical problems of borehole wall protection and plugging in deep mineral resources exploration.However,in the high temperature environment,the high temperature hydration process and solidification characteristics of cement-based materials will change,resulting in great changes in slurry material properties.The reduction of the thickening time,the increase of the water loss and the decline of the compressive strength of cement stone will greatly restrict the effect of the wall protection.Therefore,in order to effectively solve the problem of borehole wall protection and plugging in the process of deep mineral resources exploration,it is of great scientific and engineering significance to study the high-temperature rheological/solidification characteristics of composite cement-based wall protection and plugging materials.Based on the performance defects of Portland cement at high temperature,the high temperature solidification characteristics of Portland cement were studied by means of theoretical analysis,ESEM and XRD microscopic analysis,and experimental research.Specifically,there are the following studies:?1?The performance of ordinary Portland cement?P.O32.5?and G grade oil well cement at different temperatures?25?,100?,150??was tested and compared,and the high temperature performance of G grade oil well cement was found to be better than that of P.O.32.5 cement.By using the method of XRD and ESEM analysis of the microscopic curing under different temperature to 72 H P.O32.5 cement and the microstructure of class G oil well cement were analyzed,found that the increase of temperature has the duality,can not only promote the tricalcium silicate?C₃S?,dicalcium silicate?C₂S?,tricalcium aluminate?C₃A?and iron four calcium aluminate?C₄AF?hydration reaction,make its in a relatively short period of time to generate more C-S-Hgel,calcium hydroxide?C-H?,high sulfur type hydration calcium sulphoaluminate?AFt?and single sulfur type sulfur hydrated calcium aluminate?AFm?,It also damages the molecular structure and binding force of various products by intensifying the precipitation of c-s-h gel,the crystallization of c-h,the network construction between Aft and AFm and other components.Based on this,this paper probes into the reason of Portland cement's low performance at high temperature,and analyzes the hydration process of Portland cement at high temperature.?2?Portland cement performance is insufficient for the heat problem,through a series of different silicon-based materials,water reducing agent,early strength agent,material selection of nanomaterials,and scientific and reasonable orthogonal test,developed a kind of the GS,Si O2 powder 4%,25%and 0.2%GB water reducing agent,1.5%SN+0.03%SC compound early strength agent,0.2%of nano Al2O3 and class G oil well cement compound with a new type of high temperature composite cement base material.?3?Through concrete experiment,to develop a new type of high temperature composite cement-based plugging material performance characterization and protecting,the test results show that the composite materials with initial fluidity controllable,can pump period long enough,initial/final setting time and reasonable interval,stone body strength enough for higher performance,can satisfy the requirement of the high temperature of deep drilling plugging and protecting.Results analysis and evaluation of the deep under the environment of high temperature coagulation properties of Portland cement,for high temperature deep drilling plugging material and protecting the improvement provided guidance and theoretical basis,the development of new high temperature composite cement base material solves the problem of high temperature deep drilling plugging and protecting,drilling of deep exploitation of mineral resources in high temperature and the same type of retaining wall plugging construction has important reference value.