CN103073873A - Novel material pressure-out ball used in staged fracturing pitching slide sleeve opening - Google Patents

Abstract

The invention provides a new pressure-suppressing ball with polybenzimidazole and polyether ether ketone as the main materials for the multi-stage sliding sleeve segmental fracturing pitching open sliding sleeve. The main function of the pressure holding ball is to quickly and reliably realize pressure holding sealing, thereby opening the ball sliding sleeve and realizing fracturing. It has the following notable features: ①With its low density, its density is 1.5-1.6g/cm3, which can improve the ability of the pressure-holding ball to move forward quickly in a horizontal state, and it is easy to flow back; ②Using polystyrene The composite material with imidazole and polyetheretherketone as the main body has high impact strength, which ensures that the pressure holding ball has less wear and tear during the forward movement and can be reliably sealed; Under high pressure, there is no damage; ④ saves time and reduces construction risks.

Description

A new material pressure-suppressing ball for the opening of the staged fracturing pitching sleeve

technical field

The invention relates to a pressure-suppressing ball of a new material used for opening a ball-throwing sliding sleeve in the staged fracturing technology of a horizontal well, belonging to the field of petroleum exploration.

Background technique

The pressure holding ball is mainly used to open the ball sliding sleeve in the staged fracturing technology of horizontal wells in the field of petroleum exploration and development. The sliding sleeve is sealed to increase the pressure in the oil pipe until it is sealed with the valve seat and holds the pressure. When the pressure rises, the shear nail is cut to open the sliding sleeve, and the pressure holding ball goes down together with the sliding sleeve to close the lower part. After fracturing the oil layer, start fracturing the upper oil layer. Existing pressure-holding balls usually use steel balls or ordinary low-density balls. When using steel balls or ordinary low-density balls for fracturing in horizontal wells, there are the following defects: due to the high density of steel balls, they are not easy to move in horizontal wells; The ball usually adopts a hollow form. Because the wall of the steel pressure-holding ball is thin, it is easy to deform under high pressure. After deformation, the ball and the valve seat are not easy to seal and the seal is not reliable; It is easy to wear and break under impact, and it cannot achieve reliable sealing.

Contents of the invention

The purpose of the present invention is to solve the problems existing in the above-mentioned prior art, and to provide a pressure-suppressing ball of a new material used for opening the segmental fracturing pitching sleeve, which has the advantages of impact resistance, pressure resistance, low density and easy replacement in place. It can quickly reach the designated valve seat, form an effective seal with the valve seat, and open the sliding sleeve smoothly, providing effective technical support for the opening of the sliding sleeve for staged fracturing of horizontal wells. A low-density, impact-resistant, pressure-resistant, and easy-to-push new material pressure-suppressing ball that can achieve reliable sealing is provided for the pitching sleeve.

The present invention is a new material pressure-suppressing ball used for segmental fracturing pitching sliding sleeve opening, and the proportion of the new material for preparing the pressure-suppressing ball is as follows: polybenzimidazole (PBI) 35.2-37.8% (weight), poly Ether ether ketone (PEEK) 37.8-39.5% (weight), phenolic resin 13.4-15.2% (weight), carbon fiber 4.0-6.0% (weight), carbon nanotube 0.9-1.5% (weight), filler 0.4-1.0 % (weight), polyethylene 0-3.2% (weight). The filler (bonding agent) is a phenolic-epoxy cementing agent.

The invention discloses a preparation method of a pressure-suppressing ball of a new material used for segmental fracturing pitching sleeve opening, which adopts injection molding or extrusion molding; the injection molding method adopts a screw type injection molding machine or a plunger type injection molding For machining molding, the injection molding machine must meet the following conditions: ①The barrel must be able to heat up to 400-500°C; ②There is no dead corner of molten material in the barrel; ③The nozzle does not need to add a shut-off valve; ④The mold temperature should be kept at 160-500°C; 200°C or optionally heat-treat the obtained injection molded product at 200°C for 1 hour;

In the extrusion molding method described above, polybenzimidazole and polyetheretherketone, which are the main components of the new pressure-suppressing ball material, have good thermal stability and tend to form gels during processing, resulting in the formation of a gravel-like surface. Two layers of 38μm (400 mesh) stainless steel mesh sieves are used to effectively separate the formed gel during the flake-out process; at the same time, in order to reduce the surface roughness of the product, the die temperature of the mold used should be kept at (380±2) ℃.

Since the main material of this new material is polybenzimidazole and polyether ether ketone, both of which are engineering plastics, the following preparation and forming methods can be adopted according to their performance characteristics:

(1) Injection molding: It is processed by a screw type or plunger type injection molding machine. The conditions that the injection molding machine must meet are: ①The barrel can be heated to 400--500°C; ②There is no dead angle of molten material in the barrel. Due to the high viscosity of PBI and PEEK melt, it will not flow automatically, so the nozzle does not need to add a stop valve. In order to ensure PBI, PEEK has good injection molding properties and forms a high degree of crystallization during the molding process. During injection molding, the mold temperature should be kept at 160-200 °C. In this way, products with good performance can be obtained even if the polybenzimidazole and polyetheretherketone products are no longer subjected to heat treatment. If the mold temperature cannot meet the requirements, the product can be heat treated at 200°C for 1 hour.

(2) Extrusion molding: polybenzimidazole and polyether ether ketone have very good thermal stability, but gel will form during processing, resulting in the formation of a gritty surface. Mesh screens can effectively separate these gels, and two layers of 38 μm (400 mesh) stainless steel mesh screens should be used when extruding flakes. In order to reduce the surface roughness of the product, the die temperature should be maintained at (380±2)°C.

Compared with prior art, the beneficial effect of the present invention is:

1) The density of the pressure-suppressing ball of the new material of the present invention is low: the density is between 1.5-1.6/cm ³ , under the impact of the liquid flow of the same flow rate, the advantage of its low density and light weight can improve the pressure-suffocating ball in a horizontal state. After the fracturing is completed, it is easy to flow back due to its low density, which saves time and reduces construction risks.

2) The pressure holding ball of the new material of the present invention has high rigidity, good toughness, high pressure resistance, and high impact strength: it is not easily deformed under high pressure, and the test shows that the pressure holding ball of the present invention has no damage under the high pressure of 70MPa; it can Withstand the impact under high pressure to ensure that the pressure holding ball has little wear and is not easy to break during the forward movement process, and can realize safe and reliable sealing.

3) The pressure holding ball of the new material of the present invention has excellent friction resistance and wear resistance: when it travels a long distance under the action of the liquid flow, it will not be worn due to continuous impact and collision, thus realizing the connection with the pressure holding seat Effective seal.

4) The new material used in the present invention has better processing performance: it can be extruded and pressure-injected, and the molding efficiency is high, and it is easy to cut and shape.

Detailed ways

The present invention is described in further detail below:

Example

The composition ratio of the new material used in the pressure holding ball of the present invention is that the remaining components are polyethylene. They are shown in Table 1 respectively.

Table 1

The working principle of the pressure-suppressing ball of the present invention is as follows: during the construction process, a low-density pressure-suppressing ball of new material is put into the ball feeder, and pumped to the fracturing ball sliding sleeve, and sealed with the valve seat to increase the pressure in the oil pipe until The seal with the valve seat plays the role of pressure suppression. When the pressure rises, the shear pin is cut to open the sliding sleeve, and the pressure holding ball and the sliding sleeve go down together, closing the lower part to open the oil layer, and fracturing begins. After the fracturing is completed, the pressure holding ball is flowed back with the fracturing fluid to complete the fracturing operation.

Experimental test results:

Compared with the existing hollow steel ball, the test effect comparison

Comparing the test results of the two pressure-holding balls, the new material pressure-holding ball of the present invention has low density, can quickly reach the working position under the action of hydraulic pressure, and is easy to flow back; at the same time, it has high compression resistance, and the maximum working pressure is 70MPa , no wear, no deformation, and reliable sealing.

Since the development of the low-density pressure-suffocating ball of the present invention, sample processing and ground tests have been completed, and all technical parameters are consistent with the design. With the increasing exploitation of unconventional oil and gas resources, more and more directional wells and horizontal wells are used for fracturing and stimulation in shale gas and low-permeability production layers. The key technology of multi-stage fracturing, whether the ball sliding sleeve is opened or not, and whether the pressure-holding ball can be put in place are all directly related to the smooth progress of multi-stage fracturing of horizontal wells. The low-density ball of the present invention solves the difficult problems in staged fracturing reconstruction of directional wells and horizontal wells with its unique advantages, reduces risks, saves costs, and has great prospects for popularization and application.

The above-mentioned technical solution is only an embodiment of the present invention. For those skilled in the art, on the basis of the application methods and principles disclosed in the present invention, it is easy to make various types of improvements or deformations, and is not limited to The methods described in the above specific embodiments of the present invention, therefore, the above-described methods are only preferred and not limiting.

Claims (4)

1. A new material pressure-suppressing ball for segmental fracturing pitching sliding sleeve to open, it is characterized in that, the proportioning of the new material of preparing this pressure-suffocating ball is as follows: polybenzimidazole 35.2-37.8% (weight), Polyether ether ketone 37.8-39.5% (weight), phenolic resin 13.4-15.2% (weight), carbon fiber 4.0-6.0% (weight), carbon nanotube 0.9-1.5% (weight), filler 0.4-1.0% ( weight), polyethylene 0-3.2% (weight). 2. The new material pressure-holding ball for the opening of the staged fracturing pitching sleeve according to claim 1, characterized in that, the new material of the pressure-holding ball is prepared, and the filler therein is a phenolic-epoxy cement . 3. one of claim 1-2 is used for the preparation method of the new material holding back pressure ball that segmental fracturing pitching sleeve is opened, is characterized in that, adopts the method for injection molding or extrusion molding; Described injection molding method adopts Screw type injection molding machine or plunger type injection molding machine processing molding, the injection molding machine must meet the following conditions: ① barrel must be able to heat up to 400 ~ 500 ℃; ② there is no dead corner of molten material in the barrel; ③ nozzle does not need to add a shut-off valve ; ④ The mold temperature should be kept at 160-200°C or optionally heat-treat the obtained injection molded product at 200°C for 1 hour; In the extrusion molding method described above, polybenzimidazole and polyetheretherketone, which are the main components of the new pressure-suppressing ball material, have good thermal stability and tend to form gels during processing, resulting in the formation of a gravel-like surface. Two layers of 38μm (400 mesh) stainless steel mesh sieves are used to effectively separate the formed gel during the flake-out process; at the same time, in order to reduce the surface roughness of the product, the die temperature of the mold used should be kept at (380±2) ℃. 4. The application of the new material pressure-holding ball used for opening the staged fracturing ball sliding sleeve according to one of claims 1-2 in the staged fracturing technology of horizontal wells.