Research On CMC Based Eco-friendly Drilling Fluids System

Carboxymethyl cellulose(CMC)has become one of the widely used eco-friendly drilling fluids additives due to its good performance on increasing viscosity and reducing filter loss for building mud cake.However,with development of oil and gas reservoirs under complex geological conditions,CMC as the only additive in drilling fluids cannot fulfill the requirements of drilling and mining engineering.Therefore,we prepared several drilling fluids systems using diverse CMC as main additive and others as further supplements(renewable rubber powder,positive adhesive and vegetable oil lubricant)according to drilling technology indexes in sulige oilfield and national standard for environment protection.In addition,we selected the optimum system by comparing their comprehensive performance in order to apply in sulige oilfield.From the research process on eco-friendly water base drilling fluids,combined with the characteristics of outcrop shale in sulige oilfield,we developed CMC based eco-friendly drilling fluids system.In this project,we firstly selected some types of CMC as drilling fluids additives from eleven candidate by investigating their properties in CMC treated muds,as well as experiment on the linear rate of bentonite swelling and the recovery of shale cuttings on hot rolling test.Several drilling fluids systems was then constructed and they consisted of selected CMC,renewable rubber powder,positive adhesive and vegetable oil lubricant.Furthermore,the behaviors of aforementioned systems were systematically studied,including inhibition activity,ability of building mud cake,and lubricity.The optimum formula is composed of 4.0% bentonite,1.0%CMC,1.0% renewable rubber powder,0.3% MMH and 0.3% modified vegetable oil lubricant.The results showed that the expansion rate and recovery of shale in sulige oilfield are 18.65% and 83.01%,respectively.Importantly,the addition of renewable rubber powder and CMC improved the ability of building mud cake and the filter loss is 5.4mL at room temperature and medium pressure,as well as the mud cake is thin and dense.After improving the compatibility with plant lubricants,the system has good lubrication performance,and its friction coefficient is 0.0699.Actually,the system also exhibited good pollution resistance,aggravation performance and thermal stability performance.In the presence of 20% sodium chloride and 20% potassium chloride,or at the temperature of 150?,the system also maintained good filtration control capacity and rheological properties.Emphatically,the apparent viscosity of system decreased slightly and the filter loss nearly unchanged.In a word,all the performance of the CMC based eco-friendly drilling fluids system on inhibition,building mud cake and lubricity can fulfill the requirements of drilling technology in sulige oilfield.In addition,it will overcome the deficiency of current eco-friendly drilling fluid,such as high cost and large amount.The research results are of great significance to environmental protection,reservoir protection,and oil product protection.Persimmon peel contains a large amount of plant phenols and polymeric sugars,which can play a certain role in increasing viscosity,decreasing filtration loss and improving fluidity in drilling fluids,and has been put into use in various oil fields.In this paper,the waste persimmon peel was modified to improve the inhibition of persimmon peel as a drilling fluid additive,reducing the filtration loss and increasing the viscosity energy.The modified persimmon peel and CMC have good compatibility,which can turn the agricultural waste persimmon peel into a valuable asset,give greater play to its economic value,and reduce the cost of oil field exploitation.