Drilling Fluid Technology Research On Mirabilite Mine Core Drilling In Guyuan Of Ningxia

The presence of salt-gypsum bed is a potential to solute, well bore collapse, plastic flowageof rock salt and hydration, swell, well bore shrinkage of soft mudstone in drilling, which oftenbrings a series of difficulties and becomes an importance technology problem of drillingengineering which couldn't be solved completely in the world, so it is very important to choosethe technology and measures of drilling fluid in the complex salt-gypsum section rightly.This paper evaluates the undersaturated salt water drilling fluid system, the saturated saltwater drilling fluid system, the oil-based drilling fluid system, the organic salt drilling fluidintegrate synthetically. Aimed at the special geology conditions of a great deal of mudstone,halopelite and the lack of fresh water in the mirabilite mine area in Guyuan of Ningxia, choosingand optimizing the functionality additive, the undersaturated salt water salt tolerating claydrilling fluid system, the saturated salt water salt tolerating clay drilling fluid system and theundersaturated salt water sodium clay was established.According to the criterias about drilling fluid test and the laboratory test results, therheological propertyies, lost circulation, inhibition, calcium ion, magnesium ion, rock debris,sodium chloride, mirabilite resistence were also evaluated in this paper. It was indicated fromtests that the drilling fluid system had excellent rheological propertyies, wall building ability,inhibition and anti pollution ability.Borehole instability form and reason, borehole instability mechanism, borehole stabilitytechnology measures were analyzed in the paper. The borehole stability mechanism of KCl,sulfonate asphalt, silicate of the established drilling fluid system were studied.