A Method for Supplementing Energy by Water Injection in Fractured Tight Oil Reservoirs

Abstract

The invention discloses a method for replenishing energy by water injection in a fractured tight oil reservoir. 1. Determine whether the reservoir has fractures; The perforation section at the root is injected with water, and the perforation section at the toe is used for oil production. After the toe section is flooded, the packing point moves down to the toe section one by one until all the perforation sections are completely flooded. After the daily fluid production and oil production of the oil well increase and the comprehensive water cut is stabilized, multi-stage injection and multi-stage production will be carried out, and the odd-numbered fractures will be injected with water, while the even-numbered fractures will be produced at the same time, until all the perforated sections are completely watered out; 3. If it is a reservoir with fractures, Asynchronous injection and production in the same well is adopted. After the water injection section of the same well is completed, the well is shut down for a period of time. After the pressure rises to a reasonable pressure maintenance level, the well is opened to produce oil in the oil production section until all the perforation sections are flooded. Finish. Effective displacement, effectively replenishing formation energy, and improving development results.

Description

technical field [0001] The invention belongs to the field of oilfield development, and relates to a method for supplementing energy by water injection in a fractured tight oil reservoir. Background technique [0002] With the increasingly prominent contradiction between oil supply and demand in the world and the gradual shortage of high-quality oil resources, the development of ultra-low permeability reservoir resources (surface air permeability is less than 1.0mD) has become a new topic for the development of my country's oil industry. Reservoir production practice has shown that horizontal wells are an effective way to develop such reservoirs. Foreign ultra-low permeability oil reservoirs have high formation pressure coefficient (formation pressure coefficient greater than 1.2) and low viscosity of formation crude oil. Basically, long horizontal section horizontal wells are used for depletion production. Although the single well production has been greatly improved, there a...

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Problems solved by technology

However, with the prolongation of production time, the single-well production of some fracturing wells gradually declines, decreasing by 20% to 30% in half a year and 30% to 50% in one year, and the reservoir pressure maintenance level is less than 80%.

There are three main reasons for the large decline: First, the ultra-low permeability reservoirs in the Ordos Basin developed fractures, and some reservoirs developed multiple groups of natural fractures, and the extension direction of the natural fractures was inconsistent with the artificial fracture direction of the production well, and the injected water seeped along the natural fractures , leading to rapid water breakthrough and large decline in horizontal wells; second, some reservoirs are developed by water injection with a row spacing of about 150 meters. The production well pattern only deploys water injection wells at the root and toe of the horizontal well. Due to the long horizontal section of the horizontal well (600-1200 meters), the artificial fractures in the middle of the horizontal section can only rely on elastic solution gas flooding for oil production. Low pressure coefficient, low original dissolved gas-oil ratio, insufficient natural energy

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