Study On Activity Regulation Technology Of Water-Based Drilling Fluids

For a long time,the stability of the shale shaft has been a worldwide problem in oil and gas wells.Oil-based drilling fluid can better solve the problem of wellbore stability,but the system cost is high,and by environmental regulations,it is difficult to large-scale application.Therefore,the water-based drilling fluid system with strong inhibition,filtrate slowing to pass and no complicated reaction with the formation minerals is the current hot spot.And the study of activity regulation technology is one of the difficulties.Based on the theory of slime shaft stabilization technology and the research status of the evaluation of borehole wall stability and anti-collapse inhibition,the main idea of the activity regulator of organic and inorganic reagents is clarified,and by means of rolling dispersion experiment,linear expansion Experiment,pressure transfer experiment and other methods to evaluate the overall performance of activity regulator.Analyzing the effects of sodium chloride,potassium chloride,calcium chloride,magnesium chloride,potassium formate,potassium lactate,sodium lactate and glycerol on the activity of the solution and plotting the relationship between the percentage of solute and the activity of the solution.The results show that the water activity of the solution decreases with the increase of reagent mass fraction.Different ions inhibit the shale hydration ability of different ions,and at low concentration,potassium ions and formate inhibition of clay hydration performance is better.The results of slurry scattering scattering and hydration expansion experiment showed that the activity of the solution decreased with the increase of the ion content,and the ability to inhibit the hydration of the shale increased first and then stabilized.With the orthogonal test method,the formation of calcium chloride-potassium formate activity regulator(15% calcium chloride + 10% potassium formate),can effectively reduce the solution activity.The compatibility of the activity regulator with the polysulfide drilling fluid,the polyol drilling fluid and the unsaturated seawater drilling fluid was analyzed and compared.The results showed that the activity regulator was mixed with the polysulfide drilling fluid,Alcohol drilling fluid compatibility is poor,and unsaturated seawater drilling fluid compatibility is good;The inhibitory evaluation results show that the activity regulator can obviously improve the hydration capacity of the unsaturated seawater drilling fluid to suppress the hydration and dispersibility of the seawater,and the hydration expansion is increased by 50%;The small cationic inhibitor and the activity regulator in the unsaturated seawater drilling fluid system can obviously enhance the inhibition of the system and play the synergistic effect.Activity regulator can effectively improve the brine drilling fluid system to prevent the anti-collapse effect,with potential field application value.