Pollution Mechanism Of Carbonate/bicarbonate Root In Drilling Fluid

Carbonate / bicarbonate contamination issues in-depth research by removing calcium bentonite, pH of the effective control of the drilling fluid system for drilling fluid system is now often encountered in the drilling process byand the case of the calcium ion contamination in the system defined in the normal range, the drilling fluid system, the apparent viscosity, plastic viscosity the yield point Filtrate volume, etc. These properties of the drilling fluid system have been tested, so as toverification mechanism of carbonate / bicarbonate pollution, drilling fluid system, provides a powerful data analysis.To study pollution of carbonate hydrogen and carbonate, we studied the factors that affect the pH of drilling fluid. For fresh water systems, with the increase of the addition of NaCl, CaSO4 and iron are powder, the initial pH decreased, but the pH was not influenced by the addition of barite; Organic salt could increase the pH of fresh water and saturated salt water systems, and played as a buffer in saturated salt water systems. The additions of surfactant, HPAM, CMC and XC increased the pH value of both fresh water and saturated salt water systems. A strong buffering effect was observed for SMP-â…¡ in fresh water and saturated salt water systems, because pH enolic hydroxyl and sodium pH enolate react as a buffer pair. The solubities of CaCO3 and CaSiO3 are influenced by pH. In the drilling fluids with low pH, the solubities of CaCO3 and CaSiO3 increase and the calcium removing effects of traditional calcium remover such as Na2CO3 and Na2SiO3 are unsatisfactory. In this paper, new kinds of calcium removes were studied for low pH drilling fluids. Experiments results show that, CaC2O4 has low solubility and is not influenced by pH obviously. Na2C2O4 can be used as calcium remover for fresh water drilling fluids, K2C2O4 can be used as calcium remover for fresh water and brine drilling fluids.Through a series of analysis contrast test, with a better understanding of carbonate/ bicarbonate fouling mechanism. The results show that: the contamination of the drilling fluid system is to affect the system through the pH as well as a change in the concentration of the system calcium ions and other cations, thereby to influence the performance of the drilling fluid, so that further deterioration of the performance of the drilling fluid...