High-temperature Drilling Fluid Viscosity Reducer Developed

In the deep well, super deep well drilling process, borehole deeper and deeper boreholethe higher temperature, and high temperature can cause of drilling fluid thick, and add hightemperature resistant drilling fluid viscosity reducing agent is a powerful way to solve hightemperature mud thick, to drop down the viscosity reduction and cut of drilling fluid system.Present, has been synthesized with AMPS (2-acrylamido-2-methyl propane sulfonic acid)monomer of the polymer as a drilling fluid viscosity reducer, such as AMPS and naturalmaterials or a new polymer of vinyl monomers, and many other products, At laboratoryevaluation and field applications viscosity reduction effect is good, the temperature160-220℃, the strong performance of anti-sodium and anti-calcium, but these can not fully meet thedeep well and the ultra-deep well of higher temperatures and more demanding conditions offield application requirements.On the basis of analysis of the viscosity reduction mechanism, molecular design,functional groups and so on, designed and developed two viscosity reducer of AMPS–styrene(St)-acrylic acid and AMPS-styrene-itaconic acid. The two polymers main chain-C-C-structure and the side group of the benzene ring are rigid structure and have goodthermal stability; the hydration of the sulfonic acid groups and carboxyl side groups, theadsorption of the amide groups they adsorption clay surface form of diffuse double layer inthe water, negatively charged surface of clay particles and increase the thickness of thehydration layer, the reticular formation of clay particles break up, The same time, the stronglyacidic of sulfonic acid to improve the viscosity reducer of acid and alkali, the little saltsensitivity will help improve the salt tolerance of viscosity reducer, the thermal stability helpto improve temperature resistance capacity of viscosity reducer. Therefore, from a theoreticalperspective, the two terpolymers should have the ability to reduce drilling fluid viscosity andshear force at high temperature.The experiment researched synthesis by solution polymerization. The main contentinclude:BPO (Benzoyl peroxide) as initiator, the DMF (N, N-dimethylformamide) as solvent, anAMPS, styrene, acrylic acid as raw materials, another of AMPS, styrene，itaconic acid as rawmaterials, synthesis of the two kinds of high-temperature viscosity reducer, the effects ofinitiator dosage, monomer ratio, monomer concentration, reaction temperature on theviscosity reducer yield, viscosity effect, and to determine the best synthesis conditions.①Synthetic viscosity reducer St/AMPS/AA experimental conditions: nSt:nAMPS:nAA =1:1:2，BPO dosage of1.0%,35%of the monomer concentration, reaction temperature85℃, reaction time4h. The laboratory experiment showed that adding0.5%of the dose offreshwater based mud at room temperature decreased the viscosity rate of58.33%; viscosityreduction rate of76.81%after aging at260℃for16h.②Synthetic viscosity reducer St/AMPS/IA experimental conditions: nSt:nAMPS:nIA=1.2:1:1.2，BPO dosage of0.8%,30%of the monomer concentration, reaction temperature of85℃, reaction time4h. The laboratory experiment showed that adding0.5%of the dose offreshwater based mud at room temperature decreased the viscosity rate of54.70%; viscosityreduction rate of59.54%after aging at260℃for16h.The experimental results show that: monomer ratio, initiator, monomer concentration onproduct yield and viscosity reduction performance have a greater impact. Both as a resistanceto high temperature viscosity reducer in freshwater drilling fluid has good temperatureresistance and and viscosity reduction effect. The two high temperature in the freshwater-based slurry viscosity reduction effect than industrial products SF260, while the salttolerance of somewhat less.