RU2200229C2 - Manner of operation of injection well - Google Patents

Abstract

FIELD: oil production industry, technological processes of maintenance of formation pressure and oil extraction, in particular. SUBSTANCE: manner includes cyclic pumping of oilcarrying brine with oil inclusions remained in it after cleaning. On completion of its operation with decrease of intake by 25-60% of initial value brine pumping is discontinued and well is put into operation mode with cleaning of channels in downhole part of productive pool and with advance of oil front to bottom of well. Then well is transferred to category of production wells with cleaning of down-hole part of pool and extraction of oil collected in porous channels of productive pool while brine with oil inclusions was injected. Later well is transferred to category of injection wells. EFFECT: increased operational efficiency of injection well, reduced usage of materials.

Description

 The invention relates to the field of the oil industry, in particular to technological processes for maintaining reservoir pressure and oil production.

 It is known that during the operation of oil fields to ensure sufficient completeness of oil selection from the reservoir into the reservoir, water is pumped through injection wells. To clean the bottom-hole zone of the formation and normal operation of injection wells, as well as to ensure the estimated injectivity, periodically it is necessary to carry out expensive repairs.

 Currently known methods for cleaning the bottom of the formation are based on the use of special equipment and tools designed for overhaul of wells (V.M. Muravyov "Operation of oil and gas wells", M., Nedra, pp. 405-435), known methods cleaning the bottom of the formation, i.e. recovery injectivity of injection wells, associated with high material costs. The main disadvantage of the known methods is the low quality, complexity of operations, the use of expensive equipment and the high cost of work.

 The closest in technical essence is the method of operating injection wells, providing for their periodic opening and operation in the self-discharge mode, which is accompanied by a partial cleaning of the bottom of the formation and the restoration of injectivity to a certain level due to the removal of mechanical impurities, asphaltenes, resins, accumulated in the pore channels, with water and other particles, a certain positive effect is achieved by restoring the injectivity of the injection well (V. M. Muravyev "Operation is not tyanyh and gas wells ", Moscow, Nedra, 1978, pp. 142-146). The main disadvantage of this method is its relatively low efficiency, since the well can be opened for a limited time, and for the accumulation of water coming from the well, you must have a tank or barn. Subsequently, this water must be prepared and disposed of in the reservoir pressure maintenance system, which requires additional operating costs.

 The aim of the proposed method is to increase the efficiency of the injection well and reduce material costs.

 This goal is achieved by the fact that in the described method of operating injection wells, which includes cyclic injection of oil-containing produced water with oil inclusions remaining in it after treatment, after operating it to reduce injectivity by 25-60% from the initial value, the pumping is stopped and the injection well is transferred into the producing category with its subsequent return after cleaning the bottom of the formation and extracting the accumulated oil into the injection category.

 It is known that when water is injected on the filtering surface of the formation, particles of mechanical impurities are deposited, the sizes of which are equal to or greater than the sizes of pores or cracks, as well as heavy oil components (paraffin, asphaltene, resins) remaining in the produced water after it is purified to a residual oil content - up to 100 mg / l It was experimentally established that particles suspended in water pass through a porous medium if their sizes are 4-6 times smaller than the pore size. The pore sizes of most productive horizons are 2-60 microns, and the particle sizes in water are 0.2-30.0 microns. Being deposited on the filtering surface, large particles trap smaller particles, increasing the sediment layer, compacting it and reducing the permeability of the bottom-hole zone and, accordingly, the injectivity of the injection well. At the same time, oil is constantly supplied to the formation with injected water, the content of which in the water is on average 50 mg / l. As the injection well is operated, small droplets of oil and its heavy components (paraffin, resins, asphaltenes) also linger in the pores of the productive part of the formation, the injectivity of which decreases to a considerable depth. Gradually, as the injection well is operated, its injectivity drops by 50 percent or more.

 In order to reduce material costs for the restoration of the injectivity of the injection well, the water injection is stopped and transferred to the production category. In the initial period after the cessation of water injection, the process of fluid movement in the reservoir in the opposite direction begins. At the same time, solid particles, oil films and deposits of paraffin, resins and asphaltenes will be removed from the pore channels of the reservoir. After the cessation of the spout, the well is switched to the pump operation mode for 3-5 months. In the initial period of operation, mainly water will be extracted with washed films and particles of hydrocarbons and mechanical impurities. At the first stage, the produced water flows through the existing pipeline into the reservoir at the pumping station and, after sludge and separation of oil and mechanical impurities, is pumped through the PPD system into productive formations. After the well is transferred to the pumping period, the process of intensive cleaning of the pore channels from oil films and solids continues, and as the oil front moves to the bottom of the well, it is transferred to the producing category. After cleaning the bottom of the formation, i.e. restoration of injectivity of the former injection well, it is again transferred to the category of injection. Thus, a new technological technique in the claimed method is the combination of the processes of cleaning the bottom-hole zone of the injection well with oil production. The operational efficiency of the injection well is improved by combining the processes of cleaning the bottom of the formation and raising to the surface an additional volume of oil accumulated in the pore channels during the injection of oil-containing formation water. In this case, it is necessary to note an additional positive factor - the possibility of using a submersible pump designed to rise to the surface of the oil, for pumping water after restoring the injectivity of the injection well.

Claims (1)

 A method of operating an injection well, including cyclic injection of produced water with the inclusions of oil remaining in it after treatment into the producing oil formation, characterized in that after operating the well until the injectivity of the producing formation decreases by 25-60% from the initial value, the water is stopped and the well is transferred to the operating mode with cleaning of the pore channels of the bottom-hole part of the reservoir and before the oil front moves to the bottom of the well, then the well is transferred to the producing category it with cleaning the bottom of the formation and extracting the oil accumulated in the pore channels of the reservoir during injection of formation water with oil inclusions, after which the well is returned to the injection category.