Purpose and content of this study

1 research purpose of this paper

This paper focuses on the research and development of high temperature and salt resistant admixture system which is very scarce in deep and ultra deep wells. Based on the principle of molecular design, the polymer with high temperature resistance and salt resistance is used as a high temperature salt retarder and toughening agent to solve the poor salt resistance of the existing retarders and latex toughening agents, the retarding ability of the retarder at high temperature and the over dilution of the retarders. A new type of carboxylic oligomer is used as retarder and toughening agent to solve the defects of excessive sensitivity and dispersion of the existing retarder to temperature and salt, and to solve the defects of water resistance, foam and strength drop of the latex toughening agent.

2. research content of this paper

(1). Through the investigation of a large number of literature, the harm and action mechanism of early setting, late setting and brittleness of cement paste, the main components and hydration process and mechanism of oil well cement, the main types and functions of oil well cement admixtures are understood; the main types, advantages and disadvantages and development trend of oil well cement retarders and tougheners at local and abroad are determined, and the oil well admixtures currently in use are widely used It is common that the performance of oil well cement slurry becomes worse under high temperature and high salinity, and even the oil well cement slurry system is unstable, which will cause a series of adverse consequences to the cementing operation of deep and ultra deep wells. The mechanism of retarding and toughening effect of retarder and toughener respectively, the requirements of compatibility with other additives, the requirements of high temperature and salt resistance on monomer functional groups, and the influence of polymerization conditions on the properties of retarder and toughener were clarified.

(2). In this paper, amps was selected as the main monomer, and MAA, Ma, FA and other functional groups with retarding effect were selected. V50 was used as the initiator to synthesize high temperature and salt resistant retarder by free radical aqueous solution polymerization. Its structure was verified and its molecular weight was tested.

(3). in this paper, St and AMPS were selected as the main monomers, and MAA and IA were selected as monomers with stable carboxylic acid groups. The soft monomer BA, which could provide toughness for polymers, was synthesized by emulsifier free emulsion polymerization using V50 as initiator, and its structure was verified.

(4). According to the oil and gas Industry Standard SY/T 5504.1-2005, the retarder performance, temperature resistance, salt resistance, thickening and compressive strength are comprehensively evaluated. At the same time, the compatibility of retarder with other oil well cement admixtures was also investigated.

(5). According to the oil and natural gas industry standard GB/T 19139-2003, the toughening performance, temperature resistance, salt resistance, water loss reduction, thickening, compressive strength, flexural strength and gas channeling resistance of latex toughening agent were comprehensively evaluated. At the same time, the compatibility of latex toughening agent with other oil well cement admixtures was also investigated.