The Influence Of Asphalt Penetration On Drilling Fluid Performance

Iran YD oilfield is important for Sinopec in overseas.In the process of drilling,it is often encountered in the case of drilling in the asphalt layer;this can lead to change the performance of the drilling fluid,block the hole,and lock the drill bit.So the drilling efficiency is very low.Test the rheology and density of drilling fluid by using high temperature and high pressure rheology instrument and high temperature and high pressure density apparatus,then coMParison of the test result after add 5%asphalt.Researched the mechanism of asphalt intrusion.And the performance of drilling fluid can be recovered by adding emulsifier.in this paper,research is carried out by the following aspects.In this part,the test of asphalt viscosity how to change under high temperature and high pressure,the asphalt viscosity fell sharply with the temperature rise.In 47.6 ?,the asphalt began to soften.The asphalt is in the form of droplet in the drilling fluid with high temperature.Then the rheological changes of the drilling fluid under high temperature and pressure were tested;the apparent viscosity of drilling fluid decreases with increasing temperature and increases with increasing pressure.CoMPare with two curve slope,it is found that the temperature is the main factor affecting the rheological property of drilling fluid,and the effect of pressure on rheology is small.On the basis of rheological data,we can fit four rheological equations,The results show that the optimal results of four commonly used drilling fluid rheological models is H-B model,The rheological equation is ? =? ?+ K?n.Therefore,we can use H-B model to calculate the rheological parameter of drilling fluid.During the experiment,it was found that the density of drilling fluid also changed with the temperature and pressure.Therefore,the density characteristics of drilling fluid under high temperature and high pressure are studied.Under the same pressure,the experimental results show that at same pressure the density of drilling fluid is linear with temperature,and at same temperature,the model of drilling fluid density and pressure is quadratic polynomial,The best density model of drilling fluid is ?=?0exp(a1T2+a2T+a3P+a4P+a5).At the same temperature,the relationship of drilling fluid density and pressure is quadratic polynomials.The character of p-P-T in drilling fluid has been researched.The density model with temperature and pressure is the exponential model.The performance of drilling fluids can be recovered by adding emulsifier OP-10 and SDBS,while the proportion of OP-10 and SDBS is 8:2,a compound formulation for processing reagents can obtain a better effect,the recovery effect of drilling fluid is optimal.