Study On Cross-linking Mechanism And Anti-sloughing Modification Of Plant Gum Drilling Fluids

With the accelerated pace of China’s economic construction and development, the country is gradually increasing demand for mineral resources, but the majority of our old mine has appeared the phenomenon of resource depletion, so there is no doubt that geological prospecting need to expand with the direction of deeper and more complex formations to meet the country’s demand for resources in the future. Therefore, drilling coring project will often got to complex formation of break loose, easy to collapse and others. The plant gum is a natural plant polymers, hydrophilic and has good solubility, after appropriate modification its glue will have properties of adhesion, viscosity, fluid loss, rheology, lubricity, anti- sloughing, carrying rocks and damping, and have a very good protection of the pore walls and the core. The plant gum drilling fluids preparation is simple, stability, enabling natural degradation, has a good environmental protection, epitomizes excellent performance of the solid-free fluid. The engineering practice results show that, with ordinary drilling mud under crushing loose, easy to collapse and other complex stratigraphic, will led to low drilling efficiency, drilling collapse, high construction costs and low coring prone situations, while with the plant gum drilling fluids often receive good results. In order to reduce the cost of the plant gum fluid, crosslinking agent is added to increase the viscosity in a plant gum drilling fluids is essential measures, therefore the crosslinking process of plant gum drilling fluids and crosslinking agent must be clear, and to use correctly grasp the crosslinking agent is essential.In article selected seeds plant gum: guar gum, fenugreek gum, sesbania gum and holi bean gum, root plant gum: konjac gum, as the research object. Using infrared spectroscopy analysis reveals that the main component of this five plants gum containe: the main component of guar gum, fenugreek gum, sesbania gum and holi bean gum is galactomannan, the main component of konjac gum is glucomannan. Combined NMR analysis reveals the molar ratio of galactose and mannose in galactomannan of guar gum, fenugreek gum, sesbania gum and holi bean gum. After screening cross-linking agent for plant gum, finalize organic boron as crosslinker of plant gum drilling fluids. In crosslinking experiments, after five selected plant gum mixed with the organic boron, the plant gum in galactomannan category can have cross-linking reaction with organic boron, and konjac gum in glucomannan category can’t. On the basis of comparative analysis of before and after the infrared spectra of the five plant gum crosslinked, confirmed the inferred views by crosslinking experiments and analyzes derived galactomannan and organic boron crosslinked, substantially galactomannans polysaccharides hydroxyl group and an organic boron galactose branched chain released borate ion complex reaction. And further analysis presumed crosslinking mechanisms guar gum fluid crosslinking systems with viscosity method: When the small amount of added organic boron, boron mixed with an organic vegetable gums, due to only a small amount of a solution of borate ions, these borate ion will first galactomannan sugar chains close to the ends of the chain of galactose complex reaction, so that galactomannans sugar molecule galactose branched ends by the organic boron linked to each other to form a longer chain polysaccharide, is the intermolecular cross-linking, as the organic boron slowly ionized more borate ion, the borate ion complexation reaction occurs with branched galactose on the other, so that galactomannans molecule shape is formed by the irregular line slug linear change curled and contraction, i.e., intramolecular crosslinking occurs. After proposed this speculative crosslinking mechanism, the analysis of the changes in the process of cross-linking with colloidal particle size analysis, and this change with the proposed crosslinking mechanism coincide, thus confirming this view.Through the research of anti- sloughing mechanism of silicate and anti- sloughing effect of sodium silicate with different modulus, analysis obtained sodium silicate modulus of 3.2, the particle size distribution of the most uniform distribution of the most concentrated and therefore presumed to the best effect of anti- sloughing. Using sodium silicate with different modulus plant gum drilling fluids soaked standard core, by observing the extent of the collapse of the core, the use of sodium silicate 3.2 module plant gum drilling fluids core of the highest integrity, indicating it’s best anti-sloughing effect. After determining the composition of the plant gum fluid system, analysis obtained by orthogonal that the fluid system optimization formulations for: 5 ‰ GH + 1 ‰ Organoboron + 2 ‰ S-PHP + 2% Na2 O ? nSiO2(in which the organoboron is an organic boron and water by 1: 2 ratio of the mixture, Na2 O ? nSi O2 sodium silicate solution for 3.2 mode). To optimize the overall performance of the formulation was evaluated experimentally derived, GH plant gum washes anti-sloughing on the overall performance of the system to meet the performance requirements of an integrated drilling required. By the amount of expansion experiment, shale recovery experiments and film effect analysis results, the anti-sloughing effect of GH plant gum drilling fluids’ anti-sloughing system is better and able to meet the performance requirements of anti-sloughing in complex formation.