CN110552652A - carbon silica gel self-sealing core for well drilling - Google Patents

Abstract

A carbon silica gel self-sealing core for well drilling. A carbon silica gel self-sealing core comprises a core main body, wherein the core main body comprises a cap part and a sealing part at the upper end, a via hole is formed in the middle of the core main body, and the core main body mainly comprises 12-18% of carbon, 40-50% of silica gel, 14-20% of graphite nano and 20-25% of nitrile rubber in percentage by mass; the inner wall of the sealing part is in a curve shape with staggered heights, and sealing grooves are arranged on the convex parts of the inner wall of the sealing part, wherein the width of the sealing groove at the lowest end and the highest end is larger than that of the middle sealing groove, sealing rings are arranged in the sealing grooves, adjacent sealing rings are arranged at intervals, and the interval distance is more than 4 times of the sum of the widths of the adjacent sealing grooves; the outer wall of the sealing part is provided with a deformation compensation groove at the position corresponding to the sealing groove, and the inner wall of the deformation compensation groove is an arc curve. The invention can adapt to the temperature from minus dozens of degrees to minus dozens of degrees, is not limited by the temperature season, and greatly prolongs the service life.

Description

Carbon silica gel self-sealing core for well drilling

Technical Field

the invention belongs to the technical field of petroleum drilling, and particularly provides a carbon silica gel self-sealing core for drilling.

Background

During the process of drilling or repairing a well, the self-sealing core needs to be installed on a well head to prevent the occurrence of well blowout accidents in the process of repairing the well.

The self-sealing core is roughly divided into two processes from the material selection of the self-sealing core, the self-sealing core is generally made of common rubber before zero years, but the core made of the common rubber has lower wear resistance, strength, wear resistance and aging resistance, and the service life of the core is shorter; later, scientific and technological workers through the development of material science invented the polyurethane self-sealing rubber core, various performances of which are greatly improved, for example, the polyurethane self-sealing rubber core for well drilling disclosed by Chinese invention patent with publication number CN101481452A and publication number 2009.07.15 has the characteristics of strong acid resistance, high water temperature resistance, oil resistance, wear resistance and the like compared with a common rubber core. However, the polyurethane core is limited in climate temperature, and can be normally constructed from-zero to three or forty degrees in construction operation in summer, but cracks begin to appear in the core in construction operation from the temperature below zero in autumn and winter, and particularly in northern hemispheres in winter, such as northeast China, cracks frequently appear, and the cracks are more obvious in places with lower temperatures. The core can not be self-sealed due to cracks, oil injection and water injection are caused, the core needs to be frequently replaced, the environment is polluted when the core is mistakenly worked, the cost is high, and 3-5 self-sealing cores are needed for repairing a well.

From the structure, though through the effort of scientific and technological work, select polyurethane to make from the core of sealing by changing the material, the great improvement of its performance, nevertheless its intensity still can not reach the requirement in the use from a certain extent, consequently, the technical staff realizes through changing its structure, as shown in figure 1, the simple core of sealing of polyurethane that the china utility model patent of publication number CN202157778U, publication number 2012.03.07 disclosed and the simple core of sealing of polyurethane steel bar net that the china utility model patent of publication number CN201225117Y, publication number 2009.04.22 disclosed all strengthen its intensity through set up strengthening rib or/and reinforcing disc in the core body, but its processing is very inconvenient.

In addition, no matter be ordinary rubber core or polyurethane core for the reinforcing sealing performance, all realize the sliding seal of polished rod up-and-down motion through setting up multichannel sealing ring or sealed boss at core body inner wall, like the rotatory open flow rubber core of multistage seal that the chinese utility model patent of bulletin number is CN204782907U, bulletin day is 2015.11.18 and the core is proclaimed oneself to the blowout preventer that the chinese utility model patent of bulletin number is CN2030226677U, publication day is 2013.06.26, it all adopts multistage seal, great improvement sealed effect. But all the rubber is made, the boss or the sealing ring on the inner wall of the rubber core is adopted to clamp the polish rod for sealing, and the rubber core has relatively low strength, so that the abrasion is very large in the working process, and the abrasion is deviated after long-term use, so that the sealing cannot be realized, and accidents occur. In addition, in the former, the height of the boss needs to be increased to increase the clamping force and the sealing performance in order to enhance the sealing, but the strength is further reduced after the height is increased, so that the height of the boss is difficult to select in the process. In the latter case, the sealing oil receiving space formed by the smaller interval between the adjacent seal rings is also smaller and the lubricating performance is relatively poor. These problems are both in urgent need of improvement.

Disclosure of Invention

The invention solves the technical problems and provides the carbon silica gel self-sealing core for well drilling, which can adapt to temperature from minus dozens of degrees to plus dozens of degrees on the basis of keeping good wear resistance, acid resistance, oil resistance and ageing resistance, is not limited by temperature seasons and has greatly prolonged service life.

the technical scheme adopted by the invention for solving the technical problem is as follows:

A carbon silica gel self-sealing core comprises a core main body, wherein the core main body comprises a cap part and a sealing part at the upper end, a via hole is formed in the middle of the core main body, and the core main body mainly comprises 12-18% of carbon, 40-50% of silica gel, 14-20% of graphite nano and 20-25% of nitrile rubber in percentage by mass; the inner wall of the sealing part is in a curve shape with staggered heights, and sealing grooves are arranged on the convex parts of the inner wall of the sealing part, wherein the width of the sealing groove at the lowest end and the highest end is larger than that of the middle sealing groove, sealing rings are arranged in the sealing grooves, adjacent sealing rings are arranged at intervals, and the interval distance is more than 4 times of the sum of the widths of the adjacent sealing grooves; the outer wall of the sealing part is provided with a deformation compensation groove at the position corresponding to the sealing groove, and the inner wall of the deformation compensation groove is an arc curve.

the core main body also comprises 1-2% of defoaming agent by mass percent, and the defoaming agent can be selected from organic siloxane or polyether or a silicon and ether grafting product.

The core main body also comprises 1-2% of anti-aging agent and 2-4% of antioxidant by mass percent.

the curve is a sine curve or a cosine curve, and the sine chord height H is 0.1-0.2 times of the wall thickness of the sealing part.

And a plurality of second sealing grooves are arranged at intervals at the bottom and the top of the cap part.

The core main body is mainly composed of 15% of carbon, 45% of silica gel, 17% of graphite nano and 23% of nitrile rubber in percentage by mass.

foretell graphite nanometer is nanotube structure, and it is the graphite cylinder shape that length is several time microns, and its individual layer is hexahedral planar structure, radially is the nanometer size, and the slenderness ratio is 1: 10.

The process for preparing the carbon silica gel self-sealing core according to any one of claims 1 to 7, which comprises the following steps:

1) Weighing carbon in 12-18 wt%, silica gel in 40-50 wt%, graphite in 14-20 wt% and nitrile rubber in 20-25 wt%, stirring and mixing, adding defoaming agent in 1-2 wt%, and mixing in a rubber mixing machine to form gel;

2) Assembling a metal mold sprayed with a polytetrafluoroethylene coating, opening an injection hole of a grinding tool, and arranging the grinding tool on a flat vulcanizing machine;

3) injecting the gel prepared in the step 1) into a grinding tool through a grinding tool injection hole, wherein the injection pressure is 3-5 atmospheric pressures, the grinding tool is used for injection molding, and a vulcanizing machine is opened at the same time, the vulcanizing time is 2-3 hours, and the vulcanizing temperature is 150-;

4) And (4) opening the grinding tool after vulcanization, taking out the self-sealing core, repairing corners, and performing surface treatment to obtain a finished product of the self-sealing core.

the invention has the beneficial effects that:

1. The core is formed by adopting the carbon silica gel and other materials with new components, has wider application range to temperature and climate seasons on the basis of ensuring good wear resistance, oil resistance, acid resistance and ageing resistance, can be suitable for being applied to minus dozens of ℃, is particularly suitable for winter in northern hemisphere areas, can use 1-2 wells for each core in the use process in northeast winter, greatly prolongs the service life, reduces the cost, improves the working efficiency and reduces the environmental pollution compared with the prior art;

2. By selecting a new material for molding, only a new component mixing mold is needed to be molded in the processing process, and any reinforcing part is not needed to be added, so that the molding efficiency is greatly improved, and the strength integral strength is better;

3. The sealing structure and the space size of the inner wall of the sealing part of the core body are limited, so that the sealing performance and the lubricating performance are greatly improved, and the service life of the seal is also greatly prolonged;

4. the anti-aging and anti-oxidation performance can be further improved by adding the anti-aging agent and the anti-oxidation agent into the new component, and the service life can also be further prolonged;

5. The defoaming agent is added into the new component, so that the bubble amount in the core in the forming process can be further removed, the compactness and the strength of the core are improved, and the service life of the core can be further prolonged;

6. The outer side wall of the sealing part of the core main body is provided with the plurality of arc-shaped deformation compensation grooves, so that the extrusion deformation of the core in the installation and use process is compensated, the plastic cracking of the core can be controlled, and the service life of the core can be prolonged;

7. The upper edge and the lower edge of the cover part of the core are provided with a plurality of sealing grooves, and the sealing rings are arranged in the grooves, so that the radial sealing of the cover part at the cover edge can be improved;

8. because of the existence of the mixed material graphite nanometer, the composite material has the advantages of regular structure, large specific surface area, high strength, excellent intrinsic characteristics of graphite (heat resistance, corrosion resistance, thermal shock resistance, self-lubrication, biocompatibility and good thermal conductivity), and is a reinforcing filler of a rubber material with high performance and function;

9. Multistage sealed, especially with the relative middle seal ring width that the sealing ring setting at both ends is wideer, can further strengthen wherein the life of sealing ring like this, because the sealing ring at both ends receives the pressure of other parts of external world more directly, bigger, increases its width and can increase its life to reduce the change number of times of sealing ring.

Drawings

the following detailed description is made by way of example only with reference to the accompanying drawings

FIG. 1 is a schematic diagram of a prior art configuration;

fig. 2 is a schematic structural diagram of the present invention.

Detailed Description

In the embodiment, referring to the attached figure 2, the carbon silica gel self-sealing core comprises a core main body, wherein the core main body comprises a cap part 1 and a sealing part 3 at the upper end, a through hole 2 is formed in the middle of the core main body, and the core main body mainly comprises 12-18% of carbon, 40-50% of silica gel, 14-20% of graphite nano and 20-25% of nitrile rubber by mass percent; the inner wall of the sealing part is in a curve shape with staggered heights, the curve can reduce stress concentration on one hand and enable lubricating oil to flow better on the other hand, and the lubricating effect is enhanced, the convex parts of the inner wall of the sealing part are respectively provided with a sealing groove 4, wherein the width of the sealing groove at the lowest end and the highest end is larger than that of the middle sealing groove, preferably, the difference between the adjacent two is one third to one half, sealing rings are arranged in the sealing grooves, the adjacent sealing rings are arranged at intervals, and the interval distance is more than 4 times of the sum of the widths of the adjacent sealing grooves; the outer wall of the sealing part is provided with a deformation compensation groove 5 at the position corresponding to the sealing groove, the inner wall of the deformation compensation groove is an arc curve, the optimal number of the deformation compensation grooves is the same as the number of the sealing rings, and the positions of the deformation compensation grooves correspond to the positions of the sealing rings in the horizontal direction. The bottom end of the core main body inclines outwards, the arc at the inclined outer wall is arranged, and the inclined bottom end becomes thin, so that the elasticity is increased, and the sealing of the bottom end is optimized.

Preferably, the core main body also comprises a defoaming agent with the mass percent of 1-2%, wherein the defoaming agent can be selected from organic siloxane or polyether or a silicon and ether grafting product, and the defoaming agent has low price and good defoaming effect.

preferably, the core main body also comprises 1-2% of anti-aging agent and 2-4% of antioxidant by mass percent.

preferably, the curve shape is a sine curve or a cosine curve, and the sine chord height H is 0.1-0.2 times of the wall thickness of the sealing part. The proper chord height is selected to enable the sealing performance of the sealing part to be better and the service life to be longer.

Preferably, a plurality of second sealing grooves 6 are arranged at intervals at the bottom and the top of the cap part.

Preferably, the core main body is mainly composed of 15% of carbon, 45% of silica gel, 17% of graphite nano and 23% of nitrile rubber by mass percentage.

Preferably, the graphite nanometer is of a nanotube structure, the graphite nanometer is of a graphite cylinder shape with the length of several hours of micrometers, the single layer of the graphite nanometer is of a hexahedral plane structure, the radial direction is of a nanometer size, and the length-diameter ratio is 1: the nano-tube has regular structure, large specific surface area, high strength and excellent intrinsic characteristics of graphite (heat resistance, corrosion resistance, thermal shock resistance, self-lubrication, biocompatibility, thermal conductivity and good electrical conductivity), and is a reinforcing filler of a rubber material with high performance and function. However, the tendency of carbon nanotubes to entangle and the chemically inert cavities, which cause a decrease in the dispersibility and adhesion of the rubber, must be improved by physical or chemical means, such as the reduction of the aspect ratio of the carbon nanotubes by adding zinc oxide to the mixed material, in which sulfur is added to disentangle the carbon nanotubes.

the preparation process of the carbon silica gel self-sealing core comprises the following steps:

1) Weighing carbon in 12-18 wt%, silica gel in 40-50 wt%, graphite in 14-20 wt% and nitrile rubber in 20-25 wt%, stirring and mixing, adding defoaming agent in 1-2 wt%, and mixing in a rubber mixing machine to form gel;

2) Assembling a metal mold sprayed with a polytetrafluoroethylene coating, opening an injection hole of a grinding tool, and arranging the grinding tool on a flat vulcanizing machine;

3) Injecting the gel prepared in the step 1) into a grinding tool through a grinding tool injection hole, wherein the injection pressure is 3-5 atmospheric pressures, the grinding tool is used for injection molding, and a vulcanizing machine is opened at the same time, the vulcanizing time is 2-3 hours, and the vulcanizing temperature is 150-;

4) And (4) opening the grinding tool after vulcanization, taking out the self-sealing core, repairing corners, and performing surface treatment to obtain a finished product of the self-sealing core.

compared with the carbon silica gel core of the invention, the performances of the common rubber core and the polyurethane core are shown in the following table 1:

TABLE 1

the carbon silica gel self-sealing core formed by the method is used for winter experiments in Daqing oil fields, Panjin oil fields and other oil fields, and the number of the ordinary rubber cores, the polyurethane cores and the carbon silica gel cores used for repairing a well at different temperatures is specifically shown in the following table 2

TABLE 2

as can be seen from Table 2, the ordinary rubber self-sealing core and the polyurethane self-sealing core can not be used below minus 30 degrees, and the repair of 1 well can be completed only by using a plurality of the self-sealing cores between minus 30 degrees and minus 30 degrees, while the carbon silica gel self-sealing core of the present application needs to be replaced in the repair process until the temperature is lower than minus 40 degrees, and the other temperatures do not need to be replaced, and the self-sealing core can be detached for the repair of other wells after the repair without replacement is completed. The temperature adaptability of this application is wider, especially under extremely low temperature, and it is very suitable for northern hemisphere's oil well to use.

according to long-term experiments, 3 wells can be repaired by using one core of the carbon silica gel core, and 1 well can be repaired by using 3-5 cores of common rubber cores and polyurethane cores.

The carbon silica gel self-sealing core of the invention is matched with a used rubber cylinder with the specification: Φ 114 × 73 × 70; Φ 114 x 70 x 120; Φ 95 × 70 × 120; the packing specification used in a matched way is as follows: Φ 55 x 28 x 12; Φ 74 × 28 × 12; Φ 50 × 28 × 12.

the protective scope of the present invention is not limited to the above-described embodiments, and it is apparent that various modifications and variations can be made to the present invention by those skilled in the art without departing from the scope and spirit of the present invention. It is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.

Claims (8)

1. The utility model provides a core is proclaimed oneself to carbon element silica gel for well drilling, its includes the core main part, and the core main part includes cap portion (1) and sealing (3) of upper end, and core main part middle part is via hole (2), its characterized in that: the core main body is mainly composed of 12-18% of carbon, 40-50% of silica gel, 14-20% of graphite nano and 20-25% of nitrile rubber by mass percent; the inner wall of the sealing part is in a curve shape with staggered heights, and sealing grooves (4) are arranged on the convex parts of the inner wall of the sealing part, wherein the width of the sealing groove at the lowest end and the highest end is larger than that of the middle sealing groove, sealing rings are arranged in the sealing grooves, adjacent sealing rings are arranged at intervals, and the interval distance is more than 4 times of the sum of the widths of the adjacent sealing grooves; the outer wall of the sealing part is provided with a deformation compensation groove (5) at the position corresponding to the sealing groove, and the inner wall of the deformation compensation groove is an arc curve.

2. The carbon silica gel self-sealing core as claimed in claim 1, wherein: the core main body also comprises 1-2% of defoaming agent by mass percent, and the defoaming agent can be selected from organic siloxane or polyether or a silicon and ether grafting product.

3. the carbon silica gel self-sealing core as claimed in claim 1, wherein: the core main body also comprises 1-2% of anti-aging agent and 2-4% of antioxidant by mass percent.

4. The carbon silica gel self-sealing core as claimed in claim 1, wherein: the curve shape is a sine curve or a cosine curve, and the sine chord height H is 0.1-0.2 times of the wall thickness of the sealing part.

5. The carbon silica gel self-sealing core as claimed in claim 1, wherein: and a plurality of second sealing grooves (6) are arranged at the bottom and the top of the cap part at intervals.

6. The carbon silica gel self-sealing core as claimed in claim 1, wherein: the core main body is mainly composed of 15% of carbon, 45% of silica gel, 17% of graphite nano-grade and 23% of nitrile rubber by mass percentage.

7. The carbon silica gel self-sealing core as claimed in claim 1, wherein: graphite nanometer be nanotube structure, its graphite cylinder shape that is several time microns for length, its individual layer is hexahedral planar structure, radially is the nanometer size, the draw ratio is 1: 10.

8. the preparation process of the carbon silica gel self-sealing core according to any one of claims 1 to 7, which is characterized in that: the method comprises the following steps:

1) Weighing carbon in 12-18 wt%, silica gel in 40-50 wt%, graphite in 14-20 wt% and nitrile rubber in 20-25 wt%, stirring and mixing, adding defoaming agent in 1-2 wt%, and mixing in a rubber mixing machine to form gel;

2) Assembling a metal mold sprayed with a polytetrafluoroethylene coating, opening an injection hole of a grinding tool, and arranging the grinding tool on a flat vulcanizing machine;

3) Injecting the gel prepared in the step 1) into a grinding tool through a grinding tool injection hole, wherein the injection pressure is 3-5 atmospheric pressures, the grinding tool is used for injection molding, and a vulcanizing machine is opened at the same time, the vulcanizing time is 2-3 hours, and the vulcanizing temperature is 150-;

4) And (4) opening the grinding tool after vulcanization, taking out the self-sealing core, repairing corners, and performing surface treatment to obtain a finished product of the self-sealing core.