Method for raising recovery efficiency of super-deep low permeability heavy oil reservoir

Abstract

The invention provides a method for raising the recovery efficiency of super-deep low permeability heavy oil reservoir. The method comprises steps of pumping a pad fluid, pumping pressure higher than stratum fracture pressure to extrude a sand carrying fluid and sand into the stratum, and stopping a pump and closing a well after a displacement fluid is injected; opening the well, and continuingly injecting an oil soluble viscosity reducer after the well is closed for one to two days; injecting liquid carbon dioxide after the oil soluble viscosity reducer is injected, and soaking the well for the first time; continuously injecting a high temperature anti-expansion agent and steam after the well is soaked; and soaking the well for the second time, staring to produce after the well is soaked. By adopting the method for raising the recovery efficiency of the super-deep low permeability heavy oil reservoir, the fluid injection pressure and the viscosity of crude oil of the super-deep low permeability heavy oil reservoir can be greatly reduced, and high flow transfusion channels are formed in the stratum through fracturing the stratum, the flow capability of the heavy oil in the stratum can be raised, and the steam injection efficiency and the effect of thermal recovery and exploitation can be greatly raised.

Description

technical field [0001] The invention relates to the technical field of oil recovery in oil fields, in particular to a method for increasing the recovery rate of ultra-deep formation low-permeability heavy oil by using an oil-soluble viscosity reducer and liquid carbon dioxide to assist fracturing thermal recovery. Background technique [0002] With the massive consumption of conventional oil and gas resources and the rising demand for oil, heavy oil has become the main force in the development of unconventional resources due to its wide distribution and large reserves. Especially in recent years, with the development of unconventional oil and gas resources With increasing development, the development of heavy oil has also shifted from medium and shallow layers to ultra-deep low-permeability heavy oil reservoirs. [0003] Because ultra-deep low-permeability heavy oil has the characteristics of deep burial, high formation pressure, and low permeability, conventional heavy oil ...

AI Technical Summary

Problems solved by technology

Among them, steam-assisted gravity flooding (SAGD) requires that the reservoir depth is less than 1000m, and the reservoir thickness is greater than 20m, so SAGD technology cannot be applied to ultra-deep low-permeability heavy oil reservoirs; while a single viscosity reducer or CO2-assisted huff and puff viscosity reduction technology Because it is difficult to overcome the contradictions of high injection pressure, low steam dryness and small sweep range caused by low permeability and deep burial, it is also difficult to play a role in the development of ultra-deep low-permeability heavy oil reservoirs; although horizontal well steam injection development is not The above problems exist, but horizontal wells have certain requirements on reservoir thickness, and the drilling investment cost of horizontal wells is high, and the investment return period is long

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