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Method for enhancing offshore oilfield recovery

A recovery factor and oilfield technology, applied in the direction of production fluid, earthwork drilling, wellbore/well components, etc., can solve the problems of large permeability difference and serious heterogeneity in Bohai Oilfield, and achieve continuous high-speed development, Low recovery factor and the effect of reducing the amount of production sewage

Active Publication Date: 2010-01-13
CHINA NAT OFFSHORE OIL CORP +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0008] 6) Bohai Oilfield has large permeability gradients (0.1-10D), with an average of 2-4D, and serious heterogeneity;
[0011] At present, most offshore oil fields adopt water flooding oil recovery technology, but due to the aforementioned characteristics and the limitation of the service life of the oil production platform, the overall recovery rate of the oil field is only 17-25%, and the potential for improving the recovery rate is huge, and it is imminent

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0015] Example 1. Early stage polymer injection recovery in Bohai LD10-1 Oilfield

[0016] In Bohai LD10-1 oilfield, newly commissioned wells adopt early polymer injection and recovery: daily water injection volume is 200-900m 3 The polymer oil displacement agent used is ultra-high molecular weight partially hydrolyzed polyacrylamide, which is injected into the oil layer through the water injection well by means of injection pump booster. The concentration of the polymer oil displacement agent is 1200mg / L, and the daily injection volume is 600m 3 , continuous injection of polymer oil displacement agent for 5 years, a total of 1040 tons of polymer oil displacement agent dry powder was used. The results show that compared with the current conventional oil recovery technology, the recovery rate is increased by 2.95%, and the cumulative oil increase in 5 years is 1.56×10 5 m 3 , Each ton of polymer increases oil by 150 tons, and the maximum water content in the extracted oil is ...

Embodiment 2

[0017] Example 2: Polymer injection and oil production in a single well of Bohai SZ36-1 heavy oil field

[0018] In the SZ36-1 heavy oil field in the Bohai Sea, single-well polymer injection is used for oil recovery: the polymer oil displacement agent used is a hydrophobic association type polymer, which is injected by injection pump pressurization. The concentration of the polymer oil displacement agent is 1750mg / L, and the daily injection volume 500m 3 , The injection time is 576 days, and the dry polymer powder is 420 tons. The results show that: compared with the current conventional oil recovery technology, the recovery rate is increased by 2.4%, and the cumulative oil increase is 2.4×10 4 m 3 , Oil increased by 57 tons per ton of polymer, oil water content decreased from 95% before polymer injection to 48%, and actual water content decreased by 47%, achieving a very significant oil increase and water reduction effect.

Embodiment 3

[0019] Example 3. Polymer injection test of well group in Bohai SZ36-1 heavy oil field

[0020] In Bohai SZ36-1 heavy oil field, 4 wells were selected for oil recovery by polymer injection: the polymer oil displacement agent used is a hydrophobic association polymer, which is injected by injection pump pressurization, the polymer concentration is 1750mg / L, and the daily injection volume is 2400m 3 , The injection time is 3 years, and the dry polymer powder is 3143 tons. The results show that: compared with the current conventional oil recovery technology, the recovery rate is increased by 3%, and the cumulative oil increase is 1.89×10 5 m 3 , Each ton of polymer increases oil by 60 tons, and the water content of crude oil decreases by 10%.

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PUM

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Abstract

The invention discloses a method for improving petroleum mining rate in offshore petroleum well. The method of the invention injects polymer oil-displacing agent to the petroleum well when mining. With a consideration of the characteristics of offshore petroleum well mining such as short service life of the mining platform, low mining rate, etc., the invention creatively adds polymer oil-displacing agent to the well in the early stage of the oil field exploitation, which dramatically improves mining rate, keeps continuous and rapid exploitation and reduces water content of raw petroleum and has great economic, technologic and social benefits.

Description

technical field [0001] The invention relates to a method for increasing the recovery rate of an offshore oil field. Background technique [0002] Bohai Oilfield, the largest offshore oilfield in China, has more than 80% heavy oil reserves. Compared with land oilfields, Bohai Oilfield has a special environment: [0003] 1) The reservoir in Bohai Oilfield is unconsolidated sandstone, deposited in compound rhythm, and anti-rhythm is dominant; [0004] 2) Bohai crude oil is thick, and its formation viscosity is 40-700mpa.s, which is 1.5-10 times that of land oil fields; [0005] 3) The formation water in Bohai Oilfield has high salinity (>10000mg / L), especially Ca 2+ / Mg 2+ The content is greater than 600mg / L, which is 2-9 times that of land oil fields; [0006] 4) The thickness of oil layers in Bohai Oilfield is 3-6 times that of land oilfields; [0007] 5) There are many small layers in the Bohai Oilfield, and they are generally exploited in large sections, with at lea...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): E21B43/22
Inventor 周守为
Owner CHINA NAT OFFSHORE OIL CORP