Water-loss control agent for oil-well cement and preparation method thereof

Abstract

The invention discloses a water-loss control agent for oil-well cement and a preparation method thereof. The water-loss control agent is composed of the following components in parts by mole: 45 parts of 2-acrylamido-2-methacrylic acid, 45 parts of acrylamide, 10 parts of N-vinyl pyrrolidone (NVP) and 5 parts of sodium p-styrenesulfonate. The water-loss control agent for oil-well cement effectively solves the problem of decomposition under the conditions of high temperature and high pressure, and can effectively control the API water loss within 30ml. The experiment proves that the API water loss in saline cement paste is within 50ml.

Description

technical field [0001] The invention belongs to the field of additives for oil well cement, and relates to a fluid loss reducing agent for oil well cement and a preparation method thereof. Background technique [0002] Under the condition of oil exploitation and easy-to-recovery reserves decreasing, the exploration and development of oilfields has developed into oceans, complex formations, medium-deep wells, deep wells and ultra-deep wells. Oil reservoirs in western China oilfields and South China Sea are basically located in formations of about 6000m, and the bottomhole temperature increases rapidly with the increase of well depth, which brings many problems to cementing construction. Under the conditions of high temperature, high pressure and high salinity, the original There are many cement slurry additives that cannot meet the requirements, and the smooth cementing and cementing quality cannot be guaranteed. It is mainly reflected in the following aspects: 1. Under the ...

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Problems solved by technology

The oil reservoirs in western China oilfields and South China Sea are basically located in formations of about 6000m, and the bottomhole temperature increases rapidly with the increase of well depth, which brings many problems to cementing construction. Under the conditions of high temperature, high pressure and high salinity, the original Some cement slurry additives cannot meet the requirements, and cannot guarantee smooth cementing and cementing quality

It is mainly reflected in the following aspects: 1. Under high temperature and high pressure, the fluid loss reducing agent decomposes and seriously loses the original water loss control ability, which seriously affects the cementing quality; 2. Under high temperature and high pressure, the stability of the slurry changes. Poor, increasing cementing risk; 3. Poor salt resistance, greater water loss in brine cement slurry, thickening of slurry, prone to cementing accidents

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