Medium-high temperature retarder for oil well cement and preparation method thereof

Abstract

The invention discloses a medium-high temperature delayed coagulant used for oil well cement and a preparation method thereof. The method comprises the following steps: mixing 10-25wt% of 2-acrylamido-2-methyl propane sulfonic acid, 20-35% of acrylic acid, 10-35% of itaconic acid, 5-10% of N,N-dimethylacrylamide and 15-35% of acrylamide, dissolving in a certain amount of water, adjusting pH value of a mixing solution to 4-6, adding an initiator for polymerization under inert gas protection; using the medium-high temperature delayed coagulant at temperature being 80-120 DEG C. The addition amount is not sensitive, and addition amount and thickening time have good linear relation, under same condition, the thickening time of a cement mortar is increased by increasing the addition amount of the delayed coagulant, no adverse influence is generated on the cement mortar intensity; the cement mortar and a fluid loss agent of an AMPS polymer enable compatibility, technical requirement of engineering construction can be satisfied; the preparation method is simple and feasible, the reaction temperature is lower than 80 DEG C, condition is mild and controllable, and raw materials have the advantages of wide source and low cost.

Description

technical field [0001] The invention relates to oil drilling, well completion or well cementing technology, in particular to an oil well cement retarder for well cementing and a preparation method thereof. Background technique [0002] In the cementing operation of oil and gas wells, the cement slurry is pumped down into the well along the casing through the pump, and the cement slurry is returned to the annular space between the casing and the wellbore after replacing the slurry. After solidification, the purpose of isolating fluid flow between layers, supporting protective casing and protecting production layers is achieved. In well cementing construction, the cement slurry should have good pumpability before reaching the required position, and the cement slurry will lose fluidity after reaching a certain value, resulting in poor fluidity and cannot be pumped. Therefore, in order to ensure the safety of construction operations , often adding retarder to the cement slurry,...

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Problems solved by technology

[0003] At present, the widely used oil well cement retarders mainly include: lignosulfonates, hydroxycarboxylates, sugars and their derivatives, boric acid and its salts, organic phosphoric acid and its salts, organic polymers, etc. , can be roughly divided into medium-temperature (about 70°C-90°C) retarders and high-temperature (about 100°C-160°C) retarders. It is found in the practice of cementing operations that: in the transition range of about 80°C-120°C , the use effect of medium-temperature and high-temperature retarders is very unsatisfactory, and both have limitations. The former has no obvious retarding effect in this temperature range, and the latter is prone to over-retarding phenomenon in this temperature range.

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