CN115012890A - Steam pressure flooding oil extraction method for shallow and thin layer super heavy oil - Google Patents

Abstract

The invention relates to the technical field of heavy oil reservoir development, in particular to a shallow and thin super heavy oil steam pressure flooding oil extraction method. The method comprises the following steps: step 1, deploying a horizontal well; step 2, injecting a large amount of steam into the horizontal well rapidly to form multi-directional uniform cracks around the horizontal well; step 3, soaking the well; and 4, opening the well for production, reducing the oil quantity to 1t/d, and returning to the step 2. According to the method, a large amount of steam is injected quickly, multi-direction uniform volume cracks are formed around the horizontal well, the steam sweep range is expanded, the heating radius is expanded, the recovery ratio is improved, and the effect is obvious. The method disclosed by the invention is simple in steps, has better operability and practicability, and is beneficial to popularization and application.

Description

A kind of super-heavy oil vapor pressure flooding oil recovery method in shallow and thin layers

technical field

The invention relates to the technical field of heavy oil reservoir development, in particular to a method for producing oil by vapor pressure flooding of super-heavy oil in shallow and thin layers.

Background technique

At present, the proven heavy oil in place in Shengli Oilfield is 6.4× ¹⁰⁸ t, of which the proven heavy oil in place in the eastern oil area is 5.89× ¹⁰⁸ t, and 4.69× ¹⁰⁸ t has been produced so far. The proven geological reserves are 1.37×10 ⁸ t, and 5335×10 ⁴ t have been produced so far. At present, more than 80% of the active and unproduced reserves are ultra-heavy oil-extra-ultra-heavy oil reservoirs, which are an important position for stable production in the later stage.

For the exploitation of super-heavy oil reservoirs in shallow and thin layers, Chinese patent application CN109424340A discloses a method for exploiting super-heavy oil in shallow and thin layers by nitrogen injection. , and use thermal insulation casing to complete the well; (2) prepare nitrogen gas; (3) pressurize: use a nitrogen booster to pressurize the nitrogen, so that the nitrogen pressure at the outlet of the nitrogen booster is greater than that of the heavy oil reservoir. The formation pressure is lower than the fracturing pressure of the heavy oil reservoir; (4) Heating: Pass the pressurized nitrogen gas into the nitrogen heater, so that the temperature of the nitrogen gas is higher than the temperature required for the viscosity reduction of the heavy oil; (5) Nitrogen injection to reduce the viscosity : Real-time control of nitrogen injection speed, injection temperature and injection pressure is carried out through the ground control system, and the required nitrogen is slowly injected into the heavy oil reservoir to reduce viscosity; (6) Separation: the obtained heavy oil containing viscosity reduction The mixture of nitrogen, hydrocarbon gas and water is pumped to the surface through vertical wells, and after cooling, it is sent to the three-phase separation equipment for separation. Although this method has significant advantages such as environmental protection, high efficiency, and full utilization of energy, the steps are relatively complicated.

At present, Chunfeng Oilfield mainly adopts HDNS, VDNS, HNS, HDS, VNS and other methods for development, and has achieved good development results. For example, Chinese invention patent CN107664031B discloses a method for improving oil recovery by determining the pattern of horizontal well steam flooding. The method includes the following steps: step 1, selecting the physical property parameters of the horizontal well steam flooding oil layer; step 2, optimizing the deployment of the horizontal well; step 3, adopting the HDCS or HDNS mode of steam stimulation before the flooding; step 4, determining the horizontal well steam flooding Well pattern form; Step 5, determine the timing of steam flooding; Step 6, determine other parameters of steam flooding, and carry out steam flooding development. However, due to the high viscosity of crude oil, small production radius, and enrichment of remaining oil between wells, with the increase of huff and puff rounds, the formation energy is low, the decline rate is large, and the recovery degree is low.

SUMMARY OF THE INVENTION

In order to improve the recovery degree of the ultra-heavy oil reservoir, the present invention provides a method for oil recovery by vapor pressure flooding of the ultra-heavy oil. The method of the invention can effectively increase the production range of the super-heavy oil reservoir, increase the productivity of a single well, and improve the crude oil recovery rate.

To achieve the above object, the present invention adopts the following technical solutions:

The invention provides a method for oil recovery by vapor pressure flooding of super heavy oil, which comprises the following steps:

Step 1, deploy a horizontal well;

Step 2, injecting a large amount of steam rapidly into the horizontal well to form uniform fractures in multiple directions around the horizontal well;

Step 3, stew the well;

In step 4, the well is opened for production, the oil volume is reduced to 1t/d, and the process returns to step 2.

Further, in step 1, a horizontal well is deployed in the middle or lower part of the oil layer of the oil reservoir.

Further, in step 2, the steam injection dryness of the gas injection well needs to be greater than 0.5.

Further, the steam injection rate of the steam injection well is 1000-1500t/d, and the periodic injection volume is 15000-20000t.

Further, in step 3, the soaking time is 3-5 days.

Further, in step 4, the liquid sampling rate is greater than 100 t/d.

Compared with the prior art, the present invention has the following advantages:

The method of the invention forms multi-directional and uniform volume fractures around the horizontal well by rapidly injecting a large amount of steam, expands the steam sweeping range, expands the heating radius, improves the recovery rate, and has remarkable effect.

The method of the invention has simple steps, good operability and practicability, and is favorable for popularization and application.

Description of drawings

The accompanying drawings forming a part of the present invention are used to provide further understanding of the present invention, and the exemplary embodiments of the present invention and their descriptions are used to explain the present invention, and do not constitute an improper limitation of the present invention.

Fig. 1 is the flow chart of the super-heavy oil vapor pressure flooding oil recovery method in the embodiment 1 of the present invention;

FIG. 2 is a graph showing the recovery degree of shallow and thin layer heavy oil pressure flooding according to Example 2 of the present invention.

Detailed ways

It should be noted that the following detailed description is exemplary and intended to provide further explanation of the invention. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

It should be noted that the terminology used herein is for the purpose of describing specific embodiments only, and is not intended to limit the exemplary embodiments according to the present invention. As used herein, unless the context clearly dictates otherwise, the singular is intended to include the plural as well, furthermore, it is to be understood that when the terms "comprising" and/or "including" are used in this specification, it indicates that There are features, steps, operations, and/or combinations thereof.

In order to enable those skilled in the art to understand the technical solutions of the present invention more clearly, the technical solutions of the present invention will be described in detail below with reference to specific embodiments.

Example 1

As shown in Figure 1, the method for developing super-heavy oil vapor pressure flooding in shallow and thin layers includes the following steps:

In step 101, a horizontal well is deployed, which is located in the middle of the oil layer.

The flow goes to step 102 .

In step 102, the steam injection dryness of the steam injection well is greater than 0.5, the injection speed is fast, and the injection amount is large, so as to ensure that the injected steam forms multi-directional and uniform volume fractures around the horizontal well. The steam injection rate of the steam injection well is 1000t/d, and the periodic injection volume is 15000t.

The flow goes to step 103 .

In step 103, after the steam is injected, the well should be shut in, so that the steam can fully interact with the crude oil in the reservoir. Stew the well for 3 days.

In step 104, after the well is soaked, the well is opened for recovery, and the heat is used for rapid recovery, and the liquid recovery rate is greater than 100 t/d. When the daily oil production is lower than 1 t/d, return to step 102 to start a new round of production.

Example 2

The method for developing super-heavy oil vapor pressure flooding in shallow and thin layers includes the following steps:

Step 1, deploy a horizontal well, located in the middle and lower part of the oil layer.

In step 2, the steam injection dryness of the steam injection well is greater than 0.5, the injection speed is fast, and the injection amount is large, so as to ensure that the injected steam forms multi-directional and uniform volume fractures around the horizontal well. The steam injection rate of the steam injection well is 1500t/d, and the periodic injection volume is 15000t.

Step 3: After the steam is injected, the well should be shut in to allow the steam to fully interact with the crude oil in the reservoir. Stew the well for 5 days.

Step 4: After 5 days of soaking, the well is opened for recovery, using heat to recover quickly, and the liquid recovery rate is 150t/d. When the daily oil production is less than 1t/d, return to step 102, and re-inject steam to start a new round of production.

Using the reservoir numerical simulation method, the effect of the development method of the method described in Example 2 of the present invention is studied in the reservoir block. The reservoir parameters are as follows, the reservoir burial depth is 400-600m, the effective thickness is 6m, and the porosity is 35%. The permeability is 3700mD, the original oil saturation is 65%, and the crude oil viscosity is 96000mPa·s. The horizontal well is located in the middle and lower part of the oil layer, using HDNS to produce 15 cycles, the recovery degree is 10%, and then converted to steam injection pressure flooding, the steam injection rate is 1500t/d, the injection volume is 15000t, and the well is held for 5 days. When the fluid velocity is 150t/d, the daily oil production is less than 1t/d, and the oil recovery is expected to reach 12.5%, as shown in Figure 2. The method described in this embodiment realizes the effective production of the remaining oil between the super-heavy oil wells in the shallow and thin layers.

In summary, the method of the present invention makes the bottom hole pressure exceed the fracture pressure of the formation by injecting a large amount of steam rapidly, and forms multi-directional and uniform volume fractures around the horizontal well, which is beneficial for the steam to expand the steam sweeping range along the direction of the fracture, and improves the fluid seepage capacity. The remaining oil between wells is used to enhance oil recovery.

The above-mentioned embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited by the above-mentioned embodiments, and any other changes, modifications, substitutions, combinations, The simplification should be equivalent replacement manners, which are all included in the protection scope of the present invention.

Claims (6)

1. A steam pressure flooding oil extraction method for shallow and thin super heavy oil is characterized by comprising the following steps:

step 1: deploying a horizontal well;

step 2: injecting a large amount of steam into the horizontal well quickly to form multi-directional uniform cracks around the horizontal well;

and step 3: soaking the well;

and 4, step 4: and (5) opening the well for production, reducing the oil quantity to 1t/d, and returning to the step 2.

2. The method of claim 1, wherein in step 1, a horizontal well is deployed in the middle or lower portion of the reservoir.

3. The method of claim 1, wherein in step 2, the gas injection well has a steam dryness greater than 0.5.

4. The method as claimed in claim 1 or 3, wherein the steam injection speed of the steam injection well is 1000-.

5. The method of claim 1, wherein in step 3, the soaking time is 3-5 days.

6. The method of claim 1, wherein in step 4, the liquid production rate is greater than 100 t/d.

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