| 摘要 |
<p>1497785 Wellbore fluids J M JACKSON 16 March 1976 [17 March 1975] 10375/76 Heading E1F [Also in Division C3] An additive composition for use as a viscosifier in a clay-free, non argillaceous wellbore fluid comprises hydroxyalkyl guar gum and magnesia or magnesium hydroxide. Preferably the wellbore fluid is a brine containing at least 1.0% by weight of a water soluble salt of potassium, sodium or calcium. The wellbore fluid may contain a fluid loss agent, e.g. alkali or alkaline earth lignosulphonate salts, starches, gum or oil; and an electrolyte inhibitor for preventing hydration, e.g. at least 600 ppm calcium ion, at least 200 ppm aluminium ion or chromium ion, at least 1500 ppm potassium chloride, at least 5000 ppm sodium chloride or mixtures thereof. The magnesia or magnesium hydroxide is present in an amount of at least 10% by weight, e.g. 28-50% by weight, based on the weight of hydroxyalkyl guar gum, the latter being present in an amount of from 0.5-10 ppb of water. Preferably the hydroxyalkyl guar gum is either hydroxyethyl or hydroxypropyl guar gum. The wellbore fluid may be a drilling fluid, a completion fluid, a workover fluid or a fracturing fluid.</p> |
