Study Of Step-down Technology In Ultra-low Permeability Reservoirs

The peripheral oil fields of daqing belongs to special low permeability reservoir， it’s airpermeability is mainly between0.75millidarcies and1.35millidarcies and porosity is11-14%.Huge pressure drop funnel at stratum near well，high start-up pressure of the waterinjection well，water injection in the injection pressure rise fast，in the early stages of theproduction wells production declining fast，the stable yield is low and irrigation taking noeffect，which are all caused by Fuyu oil pay zone’s low permeability，low porosity，lowdegree of crude oil flow，small radius of pore throat and high bound water saturation.At present， there are two step-down increase note technologies used in ultra-lowpermeability reservoirs.One is acidification，the other is surfactant injection.But There existsserious problem in the current acidification measures that the reaction speed is too fast tosolve the problem. And although surfactant step-down increase note technology in theory canimprove water phase permeability， but in dealing with low permeability reservoir， theadsorption and emulsification caused by blockage of very serious influence， it’s so hard tosolve in fuyu oil pay zone of the hypotensive increasing note problem.This paper analyzes the research in fuyu oil pay zone of rising fast， water injectionfracturing injection wells to finish the cause of the water injection allocation， finds out themain influencing factors， and in the light of the problems and contradictions， and putsforward to take multiple acid slow-release deep solution plugging agent and weak adsorptionsurface active agent combination， improves near wellbore area of pressure drop and funnelpermeability reservoir protection， water-oil two phase flow conditions change， so as toimprove the water absorption ability， and establish an effective driving mechanism ofpurpose.In this paper，we fix the buck increase note elixir formula system and all the variousperformances was evaluated in laboratory.At last，we confirm the drug’s ingredient systemwhich practical consequence and economic benefit is both best.Through theoretical analysisand spot checking，we confirm the technology thinging that we need to use the sectionalinjection.As the result of theoretical analysis，both the drug’s ingredient and the constructtechnology of the step-down increase note technology fit ultra-low permeability reservoirsand the local demand.And the manageable result is fine.The exploration of the step-downincrease note technologies service delivery for developing of the oil field.