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A preprocessing method to improve the development effect of sagd

A technology with development effect and pretreatment, which is applied in the fields of production fluids, earthwork drilling, wellbore/well components, etc. It can solve the problems of expanding the expansion range of the steam zone, easy steam channeling, and increasing the volume of steam transversely sweeping, etc. Fluidity and thermal conductivity, strong thermal diffusion and conduction, and the effect of increasing seepage capacity

Active Publication Date: 2019-05-07
PETROCHINA CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Horizontal well steam flooding also has the characteristics of small application range, high requirements on reservoirs, easy steam channeling, and poor production effect.
Horizontal well steam huff and puff can be widely used in heavy oil reservoirs with different conditions, but there are problems such as small huff and puff production range, low recovery rate, and inability to supplement formation energy, etc.
Utilizing the properties of gas with small thermal conductivity and non-condensable gas, a heat insulation layer is formed to reduce the heat transfer rate of steam to the overlying rock layer, reduce heat loss, and improve thermal efficiency; at the same time, the non-condensable gas distributed in the upper part of the steam chamber can maintain The system pressure not only pushes the crude oil downward, but also slows down the steam’s upward overburden velocity, strengthens the lateral expansion capability of the steam chamber, and increases the steam’s lateral swept volume; The non-condensable gas affects the steam injection ability. During the operation, it is found that when the non-condensable gas is injected at the same time, the steam injection rate is reduced by about 30% due to the obvious increase in the steam chamber pressure.
Secondly, the injected gas only has the effect of heat insulation and viscosity reduction, so it can only increase the oil recovery rate, but the effect on improving the oil displacement efficiency is not obvious
[0006] Conventional fracturing technology for horizontal wells has also been applied to the development of heavy oil reservoirs, but conventional fracturing only creates a horizontal fracture at the location of the horizontal well to expand the expansion range of the steam zone

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0034] The present embodiment provides the pretreatment method that improves SAGD development effect, and this method comprises the following steps:

[0035] Reservoir characteristics: An oil reservoir in Liaohe, the reservoir depth is 550m, the porosity is 30%, the oil saturation is 75%, the permeability is 2000md, the reservoir thickness is 55m, the reservoir temperature is 35℃, and the degassed viscosity of crude oil at the reservoir temperature is 230000mPa·s .

[0036] 1) Well layout method: Drill a horizontal well at the bottom of the reservoir with a length of 400m and a distance of 5m from the bottom of the reservoir. Drill 8 vertical wells on both sides of the horizontal well with a distance of 40m from the horizontal well. The perforations are deployed in the middle of the reservoir Location.

[0037] 2) CO 2 Pretreatment stage: the first round of injection of 2 million cubic meters of supercritical CO under standard conditions 2 For gas, the formation fracture pr...

Embodiment 2

[0043] The present embodiment provides the pretreatment method that improves SAGD development effect, and this method comprises the following steps:

[0044] Reservoir characteristics: An oil reservoir in Xinjiang, the depth of the reservoir is 400m, the thickness of the oil layer is 15m, the permeability of the oil layer is 1500md, and the temperature of the oil layer is 18°C; the degassed viscosity of crude oil at the reservoir temperature is 50000mPa·s, the oil saturation is 75%, and the dip angle of the oil layer is 8° , Injection-production parameters: bottom hole dryness 75%, maximum steam injection pressure 3.5MPa.

[0045] 1) The length of the horizontal well section is designed to be 360m. One horizontal well is deployed in the middle and upper part of the reservoir as a steam injection well, and another horizontal well is deployed parallel to the horizontal well 5m away as a production well. The steam injection well is 7m away from the bottom boundary of the reservoir...

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Abstract

The invention provides a pre-treating method for improving the SAGD development effect. The pre-treating method comprises the following steps that two horizontal wells are arranged at the bottom of an oil layer of an oil reservoir; supercritical CO2 is injected into the oil layer for the first round at the operation pressure lower than bursting pressure through the two horizontal wells, soaking is conducted, when the pressure is reduced to be 0.5-1 MPa, the supercritical CO2 is injected into the oil layer for the second round at the operation pressure higher than bursting pressure, and soaking is continuously conducted; stem cycle preheating is conducted through the two horizontal wells; and after preheating is completed, continuous steam injection production is conducted on the horizontal wells. The oil reservoir is pretreated through the supercritical CO2; by greatly reducing the viscosity of crude oil, the seam demand quantity in the SAGD operation process is reduced; the cycle preheating time is shortened, the displacement efficiency of steam zones is improved, and a heavy oil reservoir can be economically and effectively exploited.

Description

technical field [0001] The invention belongs to the technical field of oil field recovery, in particular to a pretreatment method for improving the development effect of SAGD, especially a novel supercritical CO 2 Improve the oil recovery method of SAGD development effect. Background technique [0002] Heavy oil reservoirs refer to reservoirs with a degassed crude oil viscosity greater than 50,000mPa·s at the reservoir temperature. At present, horizontal well technologies are widely used in the development of domestic heavy oil fields, including steam-assisted gravity drainage, horizontal well steam huff and puff, horizontal well technology such as steam drive. The steam-assisted gravity drainage technology requires that the thickness of the oil layer must be greater than 15m, the property of the reservoir is relatively uniform, and the interlayer is discontinuous. In order to promote the thermal communication and fluid flow between the two wells, it is required to deploy t...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): E21B43/16E21B43/24
CPCE21B43/164E21B43/2408
Inventor 郭二鹏蒋有伟李秀峦王宏远魏耀李松林张大年
Owner PETROCHINA CO LTD
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