Development And Performance Study Of Flow-type Regulators For Oil-based Drilling Fluids

In order to improve the suspending capability and prop-carrying capacity of oil-base drilling fluids,the flow pattern regulator is often used to adjust the rheological properties of oil-base drilling fluids,that is,to improve the suspending capability and prop-carrying capacity.At present,the flow pattern regulator of oil-base drilling fluid employs organic soil and polymer.By selecting the appropriate modifier and modification method,we modified bentonite to prepare organic soil.Through the analysis of base oil performance,polymer flow regulator is thus selected.Amide dimethylamine and chloralkane as raw materials,the paper synthesized a kind of amide quaternary ammonium salt(primary modifier).Then in the orthogonal experiment,we determined the optimum synthesis conditions of the modifier:reaction temperature were 60?,reaction time was 5 h,the mole ratio of amide dimethylamine and chloralkane was 1:2.0.Choosing amide quaternary ammonium salt as the primary modifier,sodium dodecyl sulfate as the secondary modifier,we prepared a secondary modified organic soil(SMOS for short)with second modification.Next the orthogonal experiment was adopted to determine optimum reaction conditions of the primary modifier and the secondary modifier as follows.The primary modifier:adding amount of the primary modifier was 20%,reaction time was 4h,reaction temperature was 70?,pH of the system was 8;the secondary modifier:adding amount of secondary modifier was 5%,reaction time was 1h,reaction temperature is 80?,pH of the system is 9.Through the IR spectrum,X-ray diffraction and thermogravimetric analysis,we evaluated the basic properties of the secondary modified organic soil.When SMOS functioned as the only flow pattern regulator,3%of which would satisfy the rheological property of oil-base drilling fluids.Polymer flow regulator could get a perfect viscous shear effect with a little adding amount,and obtained a small plastic viscosity which helped to enhance the rate of penetration.By comparing key performances of oil soluble polymer flow regulator,like oil solubility and high temperature resistance,this paper selected a polymer flow regulator(PFR for short)and evaluated its basic performance with rheometer and atomic force microscope.In addition,a series of oil-base drilling fluid treatment agents were selected,such as the emulsifier,auxiliary emulsifier and wetting agent.When organic soil and polymer flow regulator served as the flow regulator,the suspending capability of oil base drilling fluids could be further improved.In contrast,when we used the remixed flow pattern regulators as the flow regulator,just a less amount could enhance the rheological property and suspending property of oil-base drilling fluids.Using the secondary modified organic soil and the polymer flow regulator separately as flow pattern regulators of the oil-base drilling fluid,we studied the influence of two flow pattern regulators on the rheological properties of oil-base drilling fluid system.The results suggested that when the secondary modified organic soil and polymer flow regulator function separately as the flow pattern regulators of oil-base drilling fluid,its adding amount reaching 3%and 1%respectively could meet the rheologic requirements of drilling fluid system.Then we remixed the secondary modified organic soil and the polymer flow regulator.When adding a small amount of the remixed flow pattern regulator into the oil-base drilling fluid system,it would meet the rheologic requirements of drilling fluid system,such as 1%secondary modified organic soil and 1%polymer flow regulator,2%secondary modified organic soil and 0.5%polymer flow regulator.In oil-base drilling fluid system,both flow pattern regulators could bear high temperature 150? and kept the stable rheological properties below the density of system 1.50 g/cm3;When adding 1%wetting agent in the oil-base drilling fluid system with remixed flow pattern regulator,the drilling fluid system's resistance to inferior soil leaching was 10%.The experimental results indicated the viscosity shear mechanism of secondary modified organic soil type and polymer flow regulator in oil-base drilling fluid system:secondary modified organic soil excerts the viscous shear function which mainly relies on hydrogen-bond interaction and intermiscibility between drilling fluid system and the primary and secondary modifiers,while polymer flow regulator obtains its viscous shear effect mainly with its own physical entanglements.