Study On Preparation And Properties Of P(ST-g-ACA)/BT Composites As Filtrate Reducer

Drilling fluid is a commonly used additive in oil and gas drilling and exploration.It can transport rock fragments,support the well wall and balance the surface pressure under the conditions of high temperature and high pressure in deep and ultra-deep well operations.Filtrate reducer is the core additive of drilling fluid,and its resistance to temperature,salt and calcium directly affects the performance of drilling fluid.Therefore,it is extremely important to carry out research on the mechanism and influencing factors of the temperature and salt resistance of filtrate reducers.In this paper,a composite filter-loss reducer,P(ST-g-ACA)/BT,was prepared with corn starch,acrylamide,2-acrylamido-2-methylpropanesulfonic acid,organo-bentonite and diallyl dimethyl ammonium chloride by monomer intercalation.The synthesis conditions were optimized,and the temperature and salt and calcium resistance properties of the product were evaluated.The structure of the product was characterized,and the mechanism of temperature and salt resistance of the product was explored.By analyzing the fluid loss reduction and rheological analysis of the product,the optimal reaction conditions were as follows: reaction time 3 h,reaction temperature 60?,initiator dosage 0.37%,bentonite dosage 8.73%,and AMPS dosage 27.58%.At the same time,using the Box-Behnken central combination test,the order of influence of each factor was: initiator dosage>AMPS dosage>bentonite dosage.The structural characterization of the product showed that the prepared composite fluid loss agent P(ST-g-ACA)/BT meets the expected design.The molecular structure contains corresponding functional groups,and the product has a “egg coil ” structure with good thermal stability.The performance of the product was evaluated for temperature resistance,salt resistance and calcium resistance.The results show that in different based drilling fluids,when P(ST-g-ACA)/BT is added at 2%,the product can anti-temperature over 180?,anti-saturated over 20.0%,anti-calcium over 1.0%.Under the composite salt water-based drilling fluid,the fluid loss is only 6.5 m L,when the dynamic plastic ratio(YP/PV)is 0.24 Pa/m Pa·s.Finally,through the mechanism analysis of P(ST-g-ACA)/BT,after adding P(ST-g-ACA)/BT,the filter cake thickness obtained by the fluid loss experiment of drilling fluid is thinner,and the filter cake is dense in SEM analysis,indicating that P(ST-g-ACA)/BT can effectively improve the fluid loss of the drilling fluid.The drilling fluid after adding P(ST-g-ACA)/BT can optimise the particle size distribution of clay particles under the conditions of high temperature and compound salt,and achieve the effect of reducing the permeability of the borehole wall.The above analysis shows that in the test based of the prepared composite filtrate reducer,the formed filter cake is of better quality and the particle size distribution of the system is small,thereby effectively improving the fluid loss control of the system.