| 摘要 |
The invention relates to clay stabilizing agents for use in an alkaline water-base fluid such as a drilling mud and the use of such clay stabilizing agents in the drilling of wells. The clay stabilizing agent comprises a polyfunctional polyamine reaction product prepared by the reaction of a polyamine base reactant with urea or a dialkylcarbonate or by reaction with urea and a dialkylcarbonate. The stabilizing agent is subject to subsequent acidification to reduce the pH thereof to a value of about 7 or less. The polyamine base reactant is selected from the group consisting of an aliphatic polyamine, a polyaliphatic polyamine, a heterocyclic polyamine, an alkylalkanol polyamine and mixtures thereof. Specifically, the base reactant comprises an aliphatic polyamine selected from the group consisting of ethylenediamine, diethylenetriamine, tetraethylenetetramine, and tetraethylenepentamine and mixtures thereof. Preferably the base reactant has at least three amino groups and a molecular weight within the range of 100-300 and more preferably 100-200. A low molecular weight alkyl acid phosphate, specifically, ethyl acid phosphate, propyl acid phosphate, butyl acid phosphate and mixtures thereof, can also be used. Preferably this supplement comprises ethyl acid phosphate. The alkyl acid phosphate may be added to the stabilizing agent in an aqueous solution subsequent to acidification of the product.
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