| 摘要 |
<p>A method of removing gelled water-soluble polysaccharide-based polymer residues from a well, the method comprising placing a breaker fluid in the well wherein the breaker fluid comprises a base fluid that is either
(a) a water-miscible or water-soluble organic liquid de-gelling agent selected from the group consisting of dimethylformamide (DMF); dimethylacetamide (DMAC); 1,3-dimethyl-3,4,5,6-tetrahydro-2(1H)-pyrimidinone (DMPU); 1 ,3-dimethyl-2-imidazolidinone (DMI); N-methylpyrrolidinone (NMP); butyrolactone; formamide; N-; N-methylformamide; dimethyl sulfoxide (DMSO); acetonitrile; propionitrile; sulfolane; N,N-dimethylpropionamide; tetramethylurea; hexamethylphosphoramide; ethylene glycol dimethyl ether; diethylene glycol dimethyl ether; 1,4 dioxane; tetrahydrofuran; N-methylmorpholine-N-oxide; trimethylamine N-oxide; and mixtures thereof; or
(b) a solution of at least one de-gelling agent in a liquid medium wherein the liquid medium is either aqueous or is a water-miscible or water-soluble organic liquid and the de-gelling agent is selected from the group consisting of:
(i) lithium chloride, lithium bromide; guanidinium chloride, and guanidinium bromide;
(ii) iodide salts of lithium, sodium, potassium, ammonium, magnesium, calcium and guanidinium;
(iii) nitrate salts of lithium, sodium, potassium, magnesium, calcium and guanidinium;
(iv) thiocyanate salts of lithium, sodium, potassium, ammonium, magnesium calcium and guanidinium;
(v) perchlorate salts of lithium, sodium, ammonium, magnesium, calcium and guanidinium;
(vi) salicylate salts of lithium, sodium, potassium, ammonium, magnesium, calcium and guanidinium;
(vii) trichloracetate and trifluoracetate salts of lithium, sodium, potassium, ammonium, magnesium, calcium and guanidinium;
(viii) urea, thiourea and methylacetamide, and
(ix) the water-miscible or water-soluble organic liquid de-gelling agents defined in (a), and the de-gelling agent(s) is present in the liquid medium in an amount of at least 10% by weight, preferably, at least 15% by weight, based on the total weight of the liquid medium and the de-gelling agent(s).</p> |
