Cross-linking agent capable of forming crosslinking jelly with CJ2-9 densifier and preparation method thereof

Abstract

The invention relates to a cross-linking agent capable of forming a crosslinking jelly with a CJ2-9 densifier and a preparation method thereof. Currently, a water base fracturing fluid is more likely to be selected for crushing of a reservoir bed home and abroad; but the water base fracturing fluid system has a high pH value and potential damage to a stratum. The cross-linking agent of the invention comprises 140-152 parts of chromic oxide, 1500-2000 parts of sulphuric acid solution with a concentration of 20%, 660-800 parts of sulfosalicylic acid, 100-200 parts of ethidene diamine and 300-600 parts of organic acid. The preparation method comprises steps of: adding the sulphuric acid solution with a concentration of 20% into an enclosed container with a stirrer; starting the stirrer; adding chromic oxide slowly and stirring for 30 min; then heating to 50 DEG C and adding sulfosalicylic acid; maintaining the temperature and reacting for 1 h; heating to 70 DEG C; adding 100 parts of ethidene diamine, maintaining the temperature and reacting for 2 h; and adding organic acids successively and reacting for 1 h to form an orange homogeneous liquid of the acidic cross-linking agent. The invention avoids adsorption between the additive and the stratum to change rock wettability and ensure the realization of additive performances in stratum.

Description

technical field

[0001] The invention relates to a cross-linking agent for acidic fracturing fluid that synthesizes a CJ2-9 thickener to form a cross-linked jelly by chemical reaction and a preparation method thereof. technical background

[0002] Due to the reliability and economy of the technology, water-based fracturing fluids are mainly used in the fracturing of most reservoirs at home and abroad, and Changqing Oilfield is no exception. Conventional water-based fracturing fluids mainly use the alkali of the guar gum series. Sexual cross-linking system, it has the deficiencies in the following aspects:

[0003] ① The pH value of the system is high, and there is potential formation damage after encountering formation ions;

[0004] ② The matching is mainly cationic additives, which are prone to adsorption, causing changes in the wettability of formation rocks and degradation of additive performance;

[0005] ③The system residue content is high, generally above 300mg / l. ...