The Damage Mechanism Of Devonian Reservoir In Xin Jiang BaMai Blocks And Completion Fluid Optimization

With the development of high and medium permeable oil fields into the later period, low permeability and ultra-low permeability reservoir development was receiving attention. The reservoirs in drill completion process were vulnerable to external fluid violations, causing reservoir pollution which affected the discovery and correct evaluation of oil reservoir, therefore reservoir protection technology is significant to the investigation, research and exploration process of oil reservoir.This paper studied on abnormal high pressure,ultra-low permeability Devonian reservoir in Xin jiang BaMai blocks , then researched the damage mechanism and completion fluids.This paper firstly introduced mechanism of oil reservoir damage, method of indoor damage evaluation mechanism and reservoir protection technology of domestic and abroad conventional reservoirs. Then this paper analyzed and concluded the current research situation of low permeability drill completion fluid reservoir protection and offered direction of completion fluid optimization technology research in this paper.Secondly, On the basis of clarifying the reservoir damage mechanism and protecting technology research, this paper understood and mastered the specific parameters including rock structure, mineral content, porosity and permeability in BaMai reservior through specific evaluation and analysis on formation water and core stone in this reservoir. And the basic characteristics are: low hole, poor connectivity between holes, low permeability, high content water sensitivity and so on. This paper preliminarily forecasted the damage mechanism of BaMai reservior: stress sensitive, water sensitivity and water-blocking damage; and through further test on reservoir indoor sensitivity, this paper mastered the specific damage pattern and damage mechanism: weak speed allergy, extremely strong salt sensitivity, a medium to high water sensitivity, stress sensitivity and water-blocking damage.Finally, the former efforts offered the clear direction for completion fluid scheme optimization: targeted add and supplement of inorganic electrolyte, inhibitors and surfactant, on the basis of evaluating original polysulfide completion fluid formula. After that, this paper clearfied the the optimal formula through single agent optimization and orthogonal experiment and analysis, and then made performance test evaluation on the optimized completion fluid formula. The evaluation results showed the good performance of the optimized completion fluid with the permeability recovery value up to 95%, inhibit the turgid rate of 92.1%, 14ml HTHP fluid loss and good compatibility between system and storage.