RU2242591C1 - Method for operation of water-floating oil deposit and device for realization of said method - Google Patents

Abstract

FIELD: oil extractive industry.

SUBSTANCE: method includes perforation of casing column in oil-saturated and water-saturated ranges of bed, lowering on tubing pipes of deep pump in such a way, that it was placed above productive layer and was connected to tail pipes column, lower end of which is lowered to pit face, and pumping away bed liquid. According to invention, speed of oil movement in hollow of casing column is increased oppositely to perforation in oil-saturated range of bed. This is realized due to decreased width of oil passing channel. For this at end of tail pipes column a device is placed - head piece in form of streamlined spindle-shaped body with thickened portion having length selected on basis of length of oil-saturated range.

EFFECT: higher oil yield.

2 cl, 3 dwg

Description

The invention relates to the oil industry and can be used in the exploitation of water-floating oil deposits, in which the reservoir is divided into water-saturated and oil-saturated intervals.

A known method for the development of oil deposits on.with. 1719621 SU, Е 21 В 43/20, 03/15/92 [1], which involves constant monitoring of the position of the oil-water contact, isolation of water inflows and subsequent perforation of wells above the created screen. However, for oil fields that are in the late stages of development, a constant movement of the oil-water contact (WOC) is characteristic upward, which, due to the presence of the vertical component of the reservoir permeability, causes the water cone to pull up to the upper perforation holes and block the oil supply channels from the oil-saturated part of the reservoir. This reduces the effectiveness of the method, which is also associated with significant costs for labor-consuming insulation and repeated shooting work.

There is also known a method of further development of water-floating oil deposits, according to which both oil-saturated and water-saturated intervals of the formation are perforated, a packer is installed in the casing at the level of oil-water contact, and during production, a portion of the produced fluid is pumped from the oil-saturated interval of the formation into the water-saturated interval of the formation. The process of pumping the indicated part of the liquid is carried out due to the reverse stroke of the plunger, patent 2175377 RU, Е 21 В 43/00, 10.27.2001 [2].

The disadvantage of this method is the reduced oil recovery due to the fact that part of the produced oil is returned to the reservoir. In addition, the method is feasible only with pumping units having working bodies for reciprocating motion, for example, with sucker rod pumps (SHG).

There is a known method of operating a flooded oil reservoir, also suitable for developing a floating oil reservoir, according to which the casing is perforated in the oil and water saturated intervals of the formation, a downhole pump is installed with a tail pipe string and a check valve at the end, and the formation fluid is produced by it pumping, patent RU 2065026, Е 21 В 43/00, 08/10/96 [3] - prototype. The specified method allows you to select products simultaneously from oil-saturated and water-saturated intervals without the formation of a water cone.

The disadvantage of this method is the reduced efficiency of oil recovery due to the fact that the bottomhole pressure is the same for both oil-saturated and water-saturated intervals. Therefore, both water and oil are selected with the same intensity. With a large water cut, the proportion of oil in the liquid being raised is small.

A device for operating a floating oil field, comprising a tubing string with a deep pump and a tubing attached to the bottom of the pump, as well as a packer, two plungers and two valves [2]. The device delivers part of the produced fluid into the water-saturated interval of the reservoir due to the reverse stroke of the pump plunger.

The disadvantage of this device is the complexity, which reduces its reliability. In addition, the specified device is operable only when it is used in conjunction with the SHGN having a reciprocating plunger.

It is also known a device for operating an oil reservoir containing a tubing string with a deep pump and a tail pipe string with a check valve attached to the specified pump, lowered into a casing perforated in both oil saturated and water saturated intervals of the formation [3] prototype .

The disadvantage of this device is that it creates the same bottomhole pressure for both oil-saturated and water-saturated intervals of the reservoir. This leads to the fact that both oil and water are extracted from the reservoir with the same intensity. With high water cut, this reduces the proportion of oil in the pumped liquid.

The objective of the invention is to increase the efficiency of the method of operating a water-floating oil reservoir and a device for implementing this method due to a more intensive extraction of the oil phase from the formation, i.e. enhanced oil recovery.

The problem is solved in that in the method of operating a water-floating oil reservoir, including perforating the casing in oil-saturated and water-saturated intervals of the formation, lowering the deep pump on the tubing so that it is located above the reservoir and connected to the column of tail pipes, the lower end which is lowered to the bottom, and pumping out the formation fluid, increase the speed of the oil in the cavity of the casing opposite the perforation in the oil-saturated interval of the reservoir due to angling oil passage channel, which at the end of the tail pipe column reinforce the tip of the streamlined body fusiform thickening selected based on the extent of oil-saturated long interval.

In the walls of the lower part of the column of tail pipes, holes are made for the produced oil.

The problem is also solved by the fact that in the device for the exploitation of a floating oil field containing a tubing string with a deep pump and a tail pipe string attached to the specified pump, lowered into the casing, perforated in both oil-saturated and water-saturated intervals of the reservoir, at the end a tail pipe string reinforced tip in the form of a winding spindle-shaped body with a thickening length selected on the basis of the length of the oil-saturated interval, and such a length of the tail pipe column that the indicated thickening would be located in the oil-saturated interval of the reservoir.

In the walls of the lower part of the tail pipe string, openings for produced oil are made.

Increasing the speed of oil movement due to the narrowing of the oil passage channel, in accordance with the well-known Bernoulli law, further reduces the pressure of the moving oil at the point of narrowing. This effect is widely used in a number of technical devices, such as carburetor, jet pump, etc.

In the practice of exploiting oil deposits, narrowing the oil passage channel is easiest to accomplish by installing a streamlined spindle-shaped body with a thickening so that the thickening is located opposite the oil-saturated interval of the reservoir. This leads to the fact that in this area the speed of the extracted oil increases and, consequently, downhole pressure decreases further. This increases the depression on the reservoir in the oil-saturated interval and makes it larger than the depression in the water-saturated interval. Accordingly, this increases the removal of oil from the oil saturated interval and increases oil recovery.

According to the results of patent studies, the application of this effect in the field of exploitation of floating oil deposits was not found. Therefore, the claimed method and device have signs of novelty and inventive step.

The essence of the proposed method and device is illustrated in figure 1. Figure 1: 1 - casing string;

2 - tubing string;

3 - deep pump;

4 - a column of tail pipes;

5 - tip in the form of a streamlined spindle-shaped body;

6 - thickening;

7 - perforation of casing pipes;

8 - oil saturated interval;

9 - water saturated interval;

10 - surface of the oil-water contact;

11 - holes in the lower part of the tail pipe string;

R $\genfrac{}{}{0ex}{}{\text{n}}{\text{zab}}$ - bottomhole pressure in the oil saturated interval of the reservoir;

R $\genfrac{}{}{0ex}{}{\text{in}}{\text{zab}}$ - bottomhole pressure in the water saturated interval of the reservoir.

Figure 2, 3 shows a section of the device.

The method is carried out by the operation of the device. The casing string 1 has a perforation 7 located both in the oil-saturated and in the water-saturated intervals 8 and 9, which are separated by the surface of the oil-water contact 10. The downhole pump 3 is lowered into the casing 1 on the tubing string 2. Any depth pump can be used a known device, for example, SHGN, electric centrifugal pump (ESP), and others. A column of tail pipes 4 is attached to the lower part of the deep pump 3. For the possibility of pumping produced fluid through the cavity of the column of tail pipes, for example, holes 11 are made in the lower part of the column 4. A tip in the form of a streamlined spindle-shaped body 5 is attached to the lower end of the column 4 with a thickening 6. As a tail pipe, any pipe can be used that provides the necessary fastening strength and whose weight does not exceed the permissible load on the design of a submersible pump installation, For example the pipe tubing, hollow rod from the SRP, pipes made of light alloy, etc. The lengths of the tubing string 2 and the tail pipe string 4 are selected so that the bulge 6 is opposite the perforation of the oil saturated interval 8.

When you turn on the deep pump 3 and with the beginning of pumping liquid pressure in the perforation 7 decreases. This creates a depression on the formation and provides an inflow of formation fluid from both water-saturated and oil-saturated intervals into the bottom of the casing.

The produced reservoir fluid, both water and oil, moves to receive the downhole pump 3 through the annular cavity between the casing string 1 and the tail pipe string 4 (for ESP) or through the holes 11 and the cavity of the tail pipe 4 (mainly for SHGN). In this case, the formation fluid moving from the area below the installation site of the spindle-shaped body 5 flows around the specified body. Since the cross-sectional area of the channel of the fluid passage between the thickening 6 of the body 5 and the wall of the casing 1 is significantly smaller than in other areas in the cavity of the casing 1, the fluid velocity in the specified channel increases sharply compared to the speed in the region of the water-saturated interval. In accordance with Bernoulli's law, this leads to the fact that the fluid pressure P $\genfrac{}{}{0ex}{}{\text{n}}{\text{zab}}$ in the region of the oil-saturated interval, additionally drops and becomes less than the pressure P $\genfrac{}{}{0ex}{}{\text{in}}{\text{zab}}$ in the area of water saturated interval. This causes additional depression on the oil saturated interval of the reservoir and increases the flow of oil into the well with a constant amount of produced water.

Thus, the proposed method and device for its implementation can increase the intensity of extraction from the reservoir of the oil phase and thereby increase the proportion of oil in the produced reservoir fluid, i.e. increase oil recovery.

Sources of information

1. A method of developing an oil reservoir. Description to the copyright certificate 1719621 SU, Е 21 В 43/20. Publ. 03/15/92.

2. A method of oil production in the late stages of development and a device for its implementation. Pat. 2175377 RU, Е 21 В 43/00, Publ. 10.27.01.

3. The method of producing waterlogged oil. Pat. 2065026 RU, Е 21 В 43/00, Publ. 08/10/96.

Claims (4)

1. A method of operating a water-floating oil reservoir, including perforating the casing in oil-saturated and water-saturated intervals of the formation, lowering the deep pump on the tubing so that it is located above the reservoir and connected to the tail pipe string, the lower end of which is lowered to the bottom, and pumping out the formation fluid, characterized in that they increase the speed of the oil in the cavity of the casing opposite the perforation in the oil-saturated interval of the reservoir due to the narrowing of the channel pr stroke oil, which on column end tip tail pipe reinforce a streamlined fusiform body thickening selected based on the extent of oil-saturated long interval. 2. The method according to claim 1, characterized in that in the walls of the lower part of the column of tail pipes holes are made for the produced oil. 3. A device for operating a floating oil field, comprising a tubing string with a downhole pump and a tail pipe string attached to the specified pump, lowered into the casing, perforated in both oil saturated and water saturated intervals of the formation, characterized in that at the end of the tail pipe string, a tip in the form of a streamlined spindle-shaped body with a thickening length selected based on the length of the oil-saturated interval and a tail pipe string length such that be housed in said thickening oil saturated reservoir interval. 4. The device according to claim 3, characterized in that in the walls of the lower part of the column of tail pipes holes are made for the produced oil.

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