Study On Preparation And Performance Of Inhibitors For Drilling Fluids

The problem of wellbore stability is a crucial link in the process of drilling, the wellbore instability likely induces some vicious incidents:such as leakage, stuck and borehole sloughing which refer to whether the well successfully and safely drilling. Especially to some mud shale formation, it is a rigorous challenge to maintain stability of the wellbore. Although oil-based drilling mud can effectively resolve the problem of drilling in mud shale formation, it coasting high, low rate of penetration and poor environment protection which restricting its application.Polyamine inhibitors drilling mud is a newest developed drilling mud, it’s a kind of water-based drilling mud which performance can compare favourably with oil-based drilling mud, and have the advantage of oil-based and water-based drilling mud. As a result that, polyamine inhibitors drilling mud has a big development potential and wide application prospect. The key of polyamine inhibitors drilling mud is to develop a kind of efficient inhibitor. Thought the survey of research and application of polyamine inhibitors drilling mud around domestic and overseas, based on the way and feature of hydration and swelling of mud shale, paper conducts molecular structure design of inhibitor, selects suitable monomer A and B and adjuvant C which can make copolymerization and have the absorbing group and polar group. Utilizing bulk polymerization, the paper makes use of orthogonal experiment method and single factor variable method to optimizing conditions of polymerization:the ratio A. B and C is 2.2:1:0.156; temperature is 150℃; polymerization time is 5h.On the basis of the above, the paper synthesizing HGI-3 inhibitor, making the overall performance evaluation of HGI-3 and analyzing it’s action mechanism. Utilizing infrared spectroscopy to characterizes polymer’s molecular structure and the result shows that HGI-3 inhibitor molecular structure contains strong adsorption group-NR and C=O and hydration group-OH; the intrinsic viscosity of HGI-3 is 0.05mL/g measured by ubbelohde viscometer. At last, paper carries out experiments, including cation exchange experiment in basic mud, grain size distribution and Zeta potential by which conducts mechanism analysis. The result shows that the molecular weight is right size to enter into clay pans and constraint it, so as to reduce the tendency to absorb water; Besides the unique molecular structure of HGI-3 can effectively form an adsorption on the clay’s surface which refrains clay hydration and swelling.Paper optimizes a set of high performance drilling fluid system based on HGI-3 inhibitor, and the formula is 3% KC1,3% SMP-2,4% solfonated bitumen,0.5% HGI-3,0.5% KPAM, 5% CaCO3,0.5% CMC, and makes performance evaluation of the system. The drilling fluid has a well salt and calcium resistance, temperature stability reach upto 180℃, recovery rate of shale is 92%, swelling prevention percentage is 12.66% and the fluid loss of HTHP is 18.4 mL. The above shows that the HGI-3 drilling fluid has good performance.