The Research And Application Of Solid Free Drilling Fluid

The solids-free drilling fluid is a water-soluble polymer, and the stability andadaptability of this aqueous solution is much better than the solid drilling fluids. Andthe system has a low flow resistance, low shear force and good rheology. It also has agood ability to carry cuttings drilling the process,and a good protection of theborehole.The common solids-free drilling fluid is a mixture,the biological polymers,cellulose derivatives, synthetic polymers and weak gel are used as tackifiers, and themodified starch, polyanionic cellulose（PAC）、sulfonated phenolic resin(SMP) areused as fluid loss additives, and the aggravating agents are used to adjust the density.The performance of the kind of polymers is very different during the process ofdrilling, just because of the adsorption of various substances is different when they arein stratum. The viscosity of most of the polymers decreases quickly in a high salinityand high temperature condition,so it is very important to research the performance ofthe polymers.This paper had made a study of some common polymer tackifier and a newmodified polysaccharide polymer(A1#).Based on the abilities of temperatureresistance and salt tolerance of the polymers.A1#and xanthan gum(XC) were chosenas tackifier,and based on both performance and market applicability, a new polymer(CAX) was made by a appropriate ratio,which has a good performance.And it is moreconducive to field applications.This paper hade also made a study of the fluid loss additives and a newpolymer(AMPS/AM/DMC) was synthesised by three monomers which was chosen asfluid loss additive. And the SMP and sulfonated lignite resin(SPNH) were also chosenas fluid loss additives, and both of them have good properties of temperature-resistantand salt tolerance, so they can control fluid loss well in high temperature and highsalinity conditionsBased on the research,a new solids-free drilling fluid has been made and which ischaracterized by high temperature resistance，high shear force resistance, good stability in high salinity, good rheological properties and low fluid loss. And it couldbe well used in the wells which are deep and high density.