A method of gravity drainage assisted steam flooding to enhance the recovery of deep ultra-heavy oil reservoirs

A technology for assisting steam and super-heavy oil, applied in the fields of fluid production, earth-moving drilling, wellbore/well components, etc., can solve the problem of heat loss, periodic oil production, decrease of oil-steam ratio, and production degree of super-heavy oil huff and puff. lower problem

Active Publication Date: 2011-12-14
PETROCHINA CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0009] (1) Deep heavy oil reservoirs are deeply buried and have large heat loss. Steam flooding and SAGD generally require high bottom well dryness, making it difficult to develop deep heavy oil;
[0010] (2) After the deep heavy oil enters high rounds of huff and puff, the periodic oil production and oil-gas ratio will decrease, and the economic benefits will become worse. If effective development methods are not adopted, the oil reservoir will be abandoned;
[0011] (3) The production degree of the super heavy oil huff and puff stage is low, and the recovery degree of the general huff and puff stage is less than 30%;
[0013] (5) The oil reservoir is deeply buried, the heat loss is serious during the steam injection process, and the dryness of the steam at the bottom of the well is low, so an effective steam cavity cannot be formed
[0014] From the perspective of ultra-heavy oil development technology in the world, for deep heavy oil reservoirs (reservoir buried depth greater than 1300m), due to the large heat loss in the wellbore during the heat injection process, there is no other effective development method except the huff and puff development technology.

Method used

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  • A method of gravity drainage assisted steam flooding to enhance the recovery of deep ultra-heavy oil reservoirs
  • A method of gravity drainage assisted steam flooding to enhance the recovery of deep ultra-heavy oil reservoirs
  • A method of gravity drainage assisted steam flooding to enhance the recovery of deep ultra-heavy oil reservoirs

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Effect test

Embodiment 1

[0160] The reservoir depth of this well group is -1390~-1410m, the average oil layer effective thickness is 56.9m, internal barriers are not developed, the average porosity is 24.5%, the average permeability is 1463md, and the crude oil viscosity at 50°C is 194000mPa·s, which is a thick layer Massive ultra-heavy oil reservoirs.

[0161] First, evaluate the development effect in this block, clarify the distribution characteristics and development potential of the remaining oil, and adopt the remaining oil splitting method of k·h·φ. The results of splitting show that the oil saturation in vertical wells is above 65%, and the average oil saturation in oil layers is above 47%.

[0162] On this basis, rough screening is carried out according to the geological parameters of the oilfield. The reservoir meets the following conditions: the buried depth of the reservoir is 1000-2000m, the thickness of the oil layer is 20-180m, the remaining oil saturation is >40%, the porosity is >18%,...

Embodiment 2

[0166]The reservoir of this well group has a burial depth of -1370~-1690m, an average oil layer effective thickness of 72m, an average porosity of 23.2%, an average permeability of 1760md, and a surface crude oil viscosity of 78960mPa·s at 50°C. It is a thick massive super heavy oil reservoir .

[0167] The remaining oil distribution research was carried out in this block, and the results of production splitting showed that the remaining oil saturation between wells was above 0.58 before diversion.

[0168] Rough screening is carried out according to the geological characteristics and development status of the oilfield. The reservoir meets the following conditions: the buried depth of the reservoir is 1000-2000m, the thickness of the oil layer is 20-180m, the remaining oil saturation is >30%, the porosity is >18%, the permeability is >200md, and the viscosity of degassed crude oil under formation conditions is >50000mPa· s.

[0169] Reservoir engineering is designed to have ...

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Abstract

The invention relates to a method for improving the oil deposit recovery ratio of deep massive extremely-viscous oil in an extraction mode of gravity drainage assisted steam flooding. In the method, superposition horizontal wells are arranged among wells by combining results of researches on the fine contrast of small geological strata of massive oil deposit, the distribution rule of interlayer, the distribution rule of remaining oil and the like and a fine research on numerical simulation; an upper superposition horizontal well is used for injecting steam, a peripheral vertical shaft is used for production, and a lower superposition horizontal well is used for discharging liquid (crude oil between condensate water and the horizontal wells); and thus, a production-injection ratio of high-speed steam injection of deep oil deposit is improved, the dryness of steam on the well bottom is improved, the pressure of an oil layer is reduced, a steam cavity is easy to expand, the swept volume is improved, a development effect is improved, and the aim of improving the recovery ratio finally is fulfilled.

Description

technical field [0001] The invention belongs to the field of oil reservoir development, and relates to the development of massive or thick-layered super heavy oil reservoirs, in particular to a gravity drainage assisted steam flooding technology. Recovery of heavy oil reservoirs. Background technique [0002] The viscosity of crude oil is a measure of the frictional resistance when one part of crude oil flows relative to another part, and is an important parameter for oil and gas field development. For heavy oil reservoirs, China's current heavy oil classification method is based on the viscosity of degassed crude oil under the condition of reservoir temperature: ordinary heavy oil viscosity 50-10000mPa s; extra heavy oil viscosity 10000-50000mPa s; super heavy oil viscosity The viscosity of crude oil is greater than 50000mPa·s. Super-heavy oil has high viscosity and poor fluidity, making it the most difficult to recover. The development of heavy oil reservoirs is mainly ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): E21B43/24E21B43/30
Inventor 任芳祥周鹰龚姚进孙洪军王平户昶昊李培武
Owner PETROCHINA CO LTD
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