A kind of anti-temperature and anti-salt viscosity reducer for drilling fluid and its preparation and application

Abstract

The invention discloses a temperature-resistant and salt-resistant viscosity reducer for a drilling fluid as well as a preparation method and an application thereof. The preparation method comprises the steps as follows: maleic anhydride and water are added to a reactor, stirred to be fully dissolved, heated and stirred at a constant speed, 2-acrylamide-2-methyl propane sulfonic acid, methacryloyloxyethyl trimethyl ammonium chloride and an initiator are added at the same time, the pH of a product is adjusted to 7-9 after the reaction, and a pale blue copolymer aqueous solution is obtained; the copolymer aqueous solution is compounded with ethylenediaminetetraacetic acid, and the temperature-resistant and salt-resistant viscosity reducer for the drilling fluid is obtained. The viscosity reducer prepared with the method has good viscosity reduction effect in heavy salt mud, and the anti-temperature capacity reaches 220 DEG C.

Description

technical field [0001] The invention relates to the technical field of viscosity reducers using organic molecules as raw materials. More specifically, it relates to a temperature-resistant and salt-resistant viscosity reducer for drilling fluid and its preparation and application. Background technique [0002] During the drilling process of deep and ultra-deep wells, due to the influence of geothermal gradient and formation pressure gradient, the drilling fluid is under the condition of high temperature above 200°C for a long time, and there are high-temperature dispersion of clay, high-temperature degradation of organic polymer compounds, and high-temperature crosslinking of treatment agents. And other effects, resulting in poor rheology of drilling fluid. For example, a large number of deep wells and ultra-deep wells being drilled or to be drilled in the Northeast Sichuan Gas Field all have a bottom hole temperature exceeding 150°C; The temperature exceeds 200°C; the Ying...

AI Technical Summary

Problems solved by technology

[0003] In order to control the thickening of drilling fluid, people began to use inorganic phosphate as early as the end of the 1930s. This kind of viscosity reducer has a good effect of reducing viscosity at low temperature, but it begins to decompose above 65°C and loses its effect of reducing viscosity.

In the 1940s, tannin was widely used as a drilling fluid viscosity reducer, but it was only suitable for shallow wells

[0004] Although FCLS has higher thermal stability than inorganic phosphate, tannin, etc., it also loses its effect at high temperature, and even causes the drilling fluid to thicken

At the same time, the chromium ions in FCLS seriously pollute the human body and the environment, and the relevant units at home and abroad have restricted its application.

After the 1990s, people began to develop various new viscosity reducers, such as the modified nitrilotrimethylene phosphonic acid (NTF-u) obtained by the methyl phosphonation reaction with organic amines and ammonium salts, and acrylic acid and isopropenylphosphine AA-IPPA copolymers prepared from acid (IPPA), these organic phosphine viscosity reducers have strong temperature resistance, but there are still problems such as short maintenance period and narrow application range; The organic silicon viscosity reducer developed by silicon compound has better temperature resistance, but the product cost is higher and the dosage is larger; while maleic anhydride (MA), sodium allyl sulfonate (AS) and 2-acrylamide - Polymer viscosity reducer developed from reactive monomers such as 2-methylpropanesulfonic acid (AMPS). During the synthesis process, due to the use of a single molecular weight regulator, the relative molecular weight distribution of the viscosity reducer is relatively wide, and the product viscosity is reduced. The performance is affected, and the temperature resistance is generally below 200°C

Images