Experimental Study On The Influence Factors Of Temperature Resistance Of Aphron Drilling Fluid

Aphron drilling fluid has been successfully applied to the drilling of exhausted oil and gas fields in recent years because of its very high low shear viscosity and special sealing mechanism.The introduction of geothermal resources into the exploration and development of geothermal resources can effectively solve the leakage problem of drilling into low pressure formation and fracture development formation,and at the same time,it can also protect geothermal reservoir.At present,the research on the performance of aphron drilling fluid mainly focuses on below 90 ?,and improving the temperature resistance of aphron drilling fluid is the premise of its popularization and application in the field of medium and high temperature geothermal drilling.In this paper,sodium lauryl sulfate(SDS)was used as foaming agent and xanthan gum(XC)as foaming agent,and the effects of bentonite on Rheological properties and filtration of aphron drilling fluid at 90?,110? and 130? were studied.After the optimal formulation,Carboxymethyl cellulose(CMC),polyanionic cellulose(PAC)and soluble starch and xanthan gum were added to study the properties of the composite system at high temperature,evaluate its synergistic effect and select the best reagent.The main work and conclusions are as follows:(1)Proper addition of bentonite can improve the hemorheology and filtration of aphron drilling fluid;At each experimental temperature,the increase of bentonite content can increase the low shear viscosity of aphron drilling fluid and reduce the water loss,but at high temperature,the excessive addition of bentonite will lead to the dispersion of clay at high temperature,which will greatly affect the properties of aphron drilling fluid.(2)The viscosity of aphron drilling fluid with polymer was tested and fitted by Origin.The fitting degree of Herschel-Bulkely model was the highest,which was the most consistent with the Rheological properties of the aphron drilling fluid.It can be seen that proper heating is beneficial to the tackifying effect of the treatment agent and can improve the shear dilution and thixotropism of the aphron drilling fluid,but the molecular decomposition and polymer degradation will be caused by the continuous heating.Resulting in poor performance;Polymer can improve the rheological properties of aphron drilling fluid and increase the low shear viscosity of aphron drilling fluid in the experimental range.The higher the amount of polymer is,the higher the aging temperature is,and the more obvious the tackifying effect is.The improvement effect of three polymers on the Rheological properties of aphron drilling fluid is as follows: CMC > PAC > soluble starch.(3)High temperature will affect the filtration characteristics of aphron drilling fluid,the higher the temperature,the greater the water loss;At 110? and 130?,the water loss of aphron drilling fluid in the control group was 1.54 and 2.36 times higher than that at room temperature,respectively.Polymer can reduce the water loss of aphron drilling fluid.In the experimental range,the water loss decreases with the increase of polymer dosage,and the filtration loss effect of polymer in high temperature environment is more obvious than that at room temperature.The improvement effect of three polymers on filtration of aphron drilling fluid from good to poor is CMC > PAC > soluble starch.