Optimization Research On Formation Damage Control Drilling Fluids Technology Of Jurassic Toutunhe Group In Fudong Slope

Fudong is the key block deployed by Xinjiang Oilfield in recent years.According to the reservoir characteristics of the Toutunhe Formation reservoir in this block,the reservoir has middle-low porosity,medium-low permeability.The high shale content is prone to hydrated clay swell and hole problems.At the same time,formation damage control is difficult.At present,the effect of several drilling fluid systems used in the block are not ideal.Through reservoir sensitivity prediction and different sensitivity evaluation experiments,it is known that the reservoir in this block has strong water sensitivity,medium-intensity alkali sensitivity,salt sensitivity and velocity sensitivity,and poor acid sensitivity.The main damage factors of the block and corresponding technical countermeasures are proposed.According to the characteristics of the reservoir and the situation of the site operation,the optimization ideas of reservoir protection drilling fluid were proposed,mainly for inhibition and plugging performance.Through the comprehensive performance evaluation and analysis of four drilling fluid systems in this block,the polymeric salt drilling fluid system was selected for optimization.A combination of amine inhibitor and“ideal packing”bridging agent was used to develop a polymeric salt water-based drilling fluid system with low damage to the reservoir.The evaluation results are better than other water-based drilling fluids,which can effectively control the filtrate loss and significantly improve the inhibition and plugging of the system.And the permeability recovery value of core dynamic formation damage is 83%,second only to 86% of the oil-based drilling fluid system,can effectively protect the reservoir,so it is recommended to promote in the Fudong block.