Study of a High-Temperature and High-Density Water-Based Drilling Fluid System Based on Non-sulfonated Plant Polymers

Abstract

The environment-friendly water-based drilling fluid system developed for the petroleum development industry cannot successfully withstand temperatures up to 180 °C, and most high temperature-resistant additives with sulfonic acid groups that have been successfully applied to water-based drilling fluid are not good for environmental protection. In order to solve the above technical problems, a non-sulfonated filtrate reducer and viscosity reducer with resistance to high temperature were prepared by using humic acid, lignin and a multifunctional monomer as raw materials. In laboratory experiments, the molecular weights of the FLO-H filtrate reducer and the VR-H viscosity reducer were 5.45 × 105 g/mol and 8.51 × 103 g/mol, respectively, and all of them showed good high-temperature resistance. The API filtration loss of the bentonite-base slurry with 3.0 wt% FLO-H was only 6.2 mL, which indicated that FLO-H had a prominent reduction in filtration loss after aging at high temperature. When the dosage of VR-H was 1.0 wt%, the plastic viscosity of the water-based drilling fluid after aging at 200 °C decreased from 71 mPa·s to 55 mPa·s, which provided excellent dispersion and dilution. The high-temperature and high-density water-based drilling fluid containing the FLO-H filtrate reducer and the VR-H viscosity reducer had good suspension stability and low filtration performance at the high temperature of 200 °C, which can meet the requirements of high-temperature deep well drilling.

A Review in Polymers for Fluid Loss Control in Drilling Operations

“…synthesized the nonsulfonated filtrate reducer with resistance to high temperature using a three‐step procedure consisting of polycondensation reaction among humic acid, lignin and formaldehyde, free radical polymerization of acrylic acid (AA), acrylamide (AM), N ‐vinylpyrrolidone (NVP) and N ‐(3‐triethoxymethiloxanyl) propyl acrylamide (APTS) in aqueous solution and an amidation reaction by mono‐ethanolamine. [ 89 ] The obtained copolymers have a very high thermal stability, thus exhibiting good high‐temperature resistance. The copolymers were used to prepare high‐performance water‐based drilling fluids and the API filtration loss with 3.0 wt% nonsulfonated copolymer as filtrate reducer was only 6.2 mL, which indicated that it had an excellent performance in filtration loss after aging at high temperature.…”

Humic acid: research progress in its structural properties, sources, preparation and application

“…在pH为9~11的水基钻井液中, 溶解的氢氧化铝和腐植酸絮凝物能迅速沉淀出来, 有 效地堵塞和密封页岩裂缝. Xu等 [114] 以腐植酸、木质 素和多功能单体为原料, 制备了一种非磺化降滤失剂 FLO-H和耐高温降黏剂VR-H. 研究结果表明, 有FLO-H和VR-H的水基钻井液在200℃的高温下具有优异的 稳定性和滤失性, 满足高温深井钻井的要求.…”