Synthesis Of High-Temperature Fluid Loss Additive And Research Of Drilling Fluid System

With the scarcity of petroleum resources, countries began to develop deep stratigraphic drilling to get more oil. Drilling issue is a technical limitation in oil exploration and development in China.Research on high-temperature drilling fluid system matching with deep strata, especially the research on fluid loss additive which is the core additive, has important significance for improving the quality of deep drilling. The complex of fluid loss additive AMPS/AM/AA/NaHm and fluid loss additive AM/AMPS/MA/NVP has a high market value.The issue of drilling cost has been concerned by drilling workers. The high-temperature fluid loss additive AMPS/AM/AA/NaHm was synthesized by cheap humic acid in this paper. The product has a better performance in fluid loss than that of humic acid terpolymer on the market. The effects of the amount of initiator, polymerization temperature, reactant ratios and pH on the synthesis of the fluid loss additive AMPS/AM/AA/NaHm were studied. The optimum conditions of synthesis were determined through orthogonally designed experiments as follows:m (AMPS):m (AM):m (AA):m (NaHm)=3:2:1:4, the initiator dosage0.7%and pH value of the reaction solution7. The characterizations and performances of product were tested, such as infrared spectroscopy, thermal gravimetric analysis, rheological properties and fluid loss properties. Results show that the fluid loss additive contains rigid groups like benzene and adsorption groups such as amide groups. The decomposition temperature of product is234℃, The product has a strong thermal stability. The amount of fluid loss additive AMPS/AM/AA/NaHm in freshwater drilling fluid, brine drilling fluid and saturated brine drilling fluid are1.5%to2.0%,1.5%to2.0%and2.0%respectively.The high-temperature fluid loss additive AMPS/AM/AA/NaHm has a strong thermal stability, but salt resistance is ordinary, The high-temperature and salt-resistance fluid loss additive AM/AMP S/MA/NVP was synthesized in aqueous solution. The fluid loss additive AM/AMP S/MA/NVP has a better performance in fluid loss and salt-resistance. The effects of the amount of initiator, polymerization temperature, reactant ratios and pH on the synthesis of the fluid loss additive AM/AMP S/MA/NVP were studied. The optimum conditions of synthesis were as follows:polymerization temperature60℃m(AM):m(AMPS):m(MA):m(NVP)=3:4:1:2, the initiator dosage0.3%and pH value of the reaction solution6. The decomposition temperature of fluid loss additive is240℃, The fluid loss additive has a better thermal-stability. The amount of fluid loss additive AM/AMPS/MA/NVP in freshwater drilling fluid, brine drilling fluid and saturated brine drilling fluid are1.5%,1.5%to2.0%and2.0%respectively.The price of loss additive A(AMPS/AM/AA/NaHm) is low, The fluid loss additive B(AMPS/AM/AA/NaHm) has a better performance in fluid loss and salt-resistance. The complex of two fluid loss additive was considered in this paper. The amount of fluid loss additive A and fluid loss additive B are0.7%and1.3%respectively while complexing.The drilling fluid system, its density1.2g/cm3, is composed of two fluid loss additives, shale inhibitors, high-temperature viscosity depressant, high-temperature lubricant and so on. Formula is as follows:4%sodium bentonite+0.4%soda+0.7%fluid loss additive A+1.3%fluid loss additive B+0.4%copolymer KP+1.0%OCL-RH+1.0%OCL-GNT+1.0%RSA+barite (increased to1.2g/cm3). The FLAPI of the drilling fluid system with200℃aging for16hours was less than5ml, and FLHTHP was22ml. The drilling fluid system achieved the desired results.