Study The Film-forming Mechanism And Pressure-bearing Ability Of Ultra-low Invasion Agent

Ultra-low invasion agent is a major additives of the study of the hot ultra-low penetration drilling fluid at Domestic and Abroad, it can be added to the water-based, oil-based or synthetic-based drilling fluids, and formation of the corresponding ultra-low penetration drilling fluid system. Ultra-low penetration drilling fluid has many advantages, for example, to prevent the pressure sticking, drilling fluid leakage, reservoir damage caused by drilling fluid invasion, enhance formation pressure capability, simple configuration, easy maintenance, etc. Thus, to effectively solve the problems faced by the end of oil and gas exploration and development, such as, pressure sticking, drilling fluid leakage, wall collapse, and formation damage and other issues, when drill into the pressure failure formation, fracture formation, broken or weak cementation of formation, low permeability reservoirs, as well as multi-pressure shale layer formation, etc.In this paper, we used infrared spectroscopy, energy dispersive, scanning electron microscopy and polarized light microscopy to study the characterized of Ultra-low invasion agent /Ultra-low permeable membrane, and obtained the corresponding spectra and micro-display, further analysis derived ultra-low invasion agent composition structure and film-forming mechanism. The results show that ultra-low invasion agent have a wide range of HLB values, and contains a large number of hydrophilic and lipophilic groups, added to the drilling fluid and reaches a certain concentration, ultra-low invasion agent will gathered to form spherical, rod or sheet micelle. These micelles with the solid phase particles in the drilling fluid together to form ultra-low permeable membrane under pressure, depend on intermolecular adsorption and membrane can be deformation, and can block different permeability formation.The latter part of the exploitation of Daqing Oilfield , the main oil region of La, Sa, Xing, Pu, etc, will faced large pressure between difference complex blocks, prone to lost circulation, and wall collapse incidents. We respectively studied the impact of ultra-low permeable membrane elements, including pressure, temperature, core permeability and ultra-low invasion agent concentration in the drilling fluid, by high temperature and pressure moving water loss instrument. The results show that the greater pressure, the higher temperature, the greater core permeability, plus the amount of ultra-low invasion agent in the drilling fluid, the formation of ultra-low permeable rupture more easily. Ultra-low invasion agent in the drilling fluid concentrations reached more than 1.5%, be able to form an effective ultra-low perme- able membrane, with the increase of ultra-low invasion agent, the carrying capacity of membrane will be gradually enhanced. At the same time, this paper also studied the impact of ultra-low invasion agent on micro-foam drilling fluid system. The results show that micro-form drilling fluid has a greater pressure capacity. As a result, provide on-site guidance to the application of ultra-low invasion agent, to maximize the economic benefits of oil field.