Development And Evaluation Of Transition Metal Zirconium Ionic Complexes Thinners

The increasingly stringent environmental regulations and growing energy demands have influenced the industry to move toward water-based drilling fluids(WBM)in applications where oil-based drilling fluids(OBM)have previously been preferred,including high-temperature,high-pressure(HTHP)wells.Dispersed WBM's have historically been preferred since they are easy to maintain and economically competitive.As the requirements for efficient and successful drilling became more demanding,thinners that provided the necessary technical performance such as chrome lignosulfonates or chrome lignites came into wide use.However,these chrome-containing compounds have not been permissible globally in many areas for a number of years due to environmental regulations restricting chrome use.In this paper,the zirconium ion complexes were synthesized with organic carboxylic acid,polymeric organophosphate,polymeric carboxylate and sulfonic acid carboxylic acid copolymer using the chemical principle of transition metal ion complex and the thinner molecular structure of water-based drilling fluid viscosity reducing agent.And the complexes formed by the anion ligand were used to evaluate the thinner effects of the dispersant water-based drilling fluid.The results show that,organic ligands that form complexes with zirconium ions and have a thinner effect or which can increase the viscosity reduction effect are mainly citric acid and hydroxyethylidene diphosphonic acid(HEDP),in which the the complex of zirconium ion and citric acid exhibiting better performance.The ratio of zirconium ion to citrate anion ligand in the complex has a great influence on the viscosity reduction of the product,and its optimal molar ratio is 1.25: 1.0.The synthesized thinner product(zirconium-citric acid complex)can be resistant to temperatures up to 200 ? in water-based bentonite drilling fluid,with good thinner effect in the range of pH 8.0 ~ 12.0;with the equal technicial level with commercial anti-high temperature thinners at home and abroad.The field test results show that,the synthesized thinner product can not only reduce the viscosity of the drilling fluid but also improve the weak gel properties of the drilling fluid by silicon-based drilling fluid with the high low density solid content.The zirconium-citrate complex thinner product has solved the problems of dispersed water-based bentonite drilling fluids including poor rheological stability at high temperature,tending to thickening and gelation,improving the capability of cuttings.