CN1032367C - Oil well porthole resin small ball sealing agent and its made method - Google Patents

Abstract

The invention relates to an oil well blast hole resin pellet plugging agent. The epoxy resin mixed with softener and curing agent is added into the dispersion medium to make resin balls, and the resin balls are injected into the blasthole after the resin balls are gelled and before curing, so that the high-permeability water-flooded layer can be blocked and the oil well Resume normal production. The plugging agent of the invention can save a large amount of plugging agents because it only plugs blastholes, and can meet the production requirements of oil wells with large pressure difference after plugging. The construction process is simple, and it is convenient for popularization and application.

Description

Oil well blasthole resin ball plugging agent and its preparation method

The invention relates to the field of drilling compositions, in particular to an oil well blast hole resin pellet plugging agent and a preparation method thereof.

In my country's oil exploitation, 80% of the crude oil is produced by injecting water into the oil reservoir. An oil reservoir is often composed of many oil layers. Due to the difference in permeability among the oil layers, the injected water will rush along the high permeability layer, causing the oil well to be flooded prematurely. In order to extract crude oil from oil layers with low permeability, people use chemical agents to block high-permeability water-flooded layers, so that oil wells can resume normal production.

So far, there are two types of chemical agents proposed to block water-flooded formations: [1] polymer materials (such as polyacrylamide and its derivatives) and cross-linking agents, which form gels in oil reservoirs; [2] ] Two kinds of chemical drugs are used to form a solid precipitate in the oil layer (such as water glass plus calcium chloride). Its characteristic is that the pores in the oil layer are blocked by gel or solid precipitation. The above two types of methods can achieve the purpose of water blocking under certain conditions, but the amount of chemical agents used is more than 1 ton. And the [1] type has limited gel strength. When the production pressure difference of the oil well exceeds 4MPa, the gel will be spit out from the oil layer and the water plugging will fail; the [2] type must inject the two drugs separately, and inject them in the middle. Diesel is used as spacer fluid. During the injection process, as the injection radius expands, the spacer fluid becomes thinner, and the second agent passes through the spacer fluid and meets the first agent before chemical reaction can occur, resulting in solid precipitation. The complexity of the pores of the oil layer prevents the two agents from fully contacting, and only part of the contact acts as a blockage. Though above-mentioned two kinds of methods are technically feasible, drug expense is all very big (more than 10,000 yuan). Type [1] cannot meet the requirements of large pressure difference production in oil wells; type [2] not only has waste of medicines, but also has complex construction techniques, which limits its wide application.

U.S. Patent No. 3,842,905 is a plug used for oil well cementing, and it provides a special tool for oil well cementing. This patent mainly introduces the structure and the method of making of the plug with pressure relief hole. The plug shell is made of lead, and the inner filler is epoxy resin and lead powder. The epoxy resin is only used as a binder for the lead powder, not a plugging agent.

The object of the present invention is to provide a resin ball plugging agent for oil well blastholes and its preparation method, which has low plugging utilization, high plugging strength, simple plugging process and easy construction.

The object of the present invention is achieved like this: the epoxy resin that is mixed with softening agent and curing agent is added in dispersion medium and made resin ball, after this resin ball is gelled and before curing, inject in blast hole, said resin ball The components and content ratio of the ball sealing agent are as follows: 100 grams of epoxy resin, 15-25 milliliters of dibutyl phthalate, 20-35 milliliters of ethylenediamine, 0.8-1.2 (weight)% polyacrylamide aqueous solution 0.8～1.5 kilograms, just can reach the purpose of the present invention by blocking up the oil well blast hole with this resin bead plugging agent.

The present invention will be described in detail below in conjunction with the accompanying drawings.

Accompanying drawing 1 is a schematic diagram of an oil well blast hole, accompanying drawing 2 is a simulation test diagram of plugging a blast hole, and accompanying drawing 3 is a schematic diagram of an oil well structure and construction of plugging a blast hole.

The oil well blasthole is a hole formed by shooting through the metal casing of the high-energy perforating bullet and the cement that fixes the casing. It is the throat where the bulk flows from the oil layer to the oil well. In accompanying drawing 1, 1 represents casing, 2 is cement, 3 is oil layer, 4 is blast hole, 5 is wellbore. The focus of the resin ball plugging agent is to seal the blast hole of the oil well. As long as the blast hole is firmly blocked, water will not enter the oil well. In order to meet the needs of oil well production under the pressure difference of 6-7Mpa, the pressure difference that the blasthole can withstand after plugging should be greater than 8Mpa. Therefore, the oil well blasthole plugging agent uses high-strength epoxy resin as the main raw material.

Epoxy resin is a viscous substance. When an appropriate amount of softener (liquid dibutyl fat) and curing agent (liquid ethylenediamine) are added, it can form a liquid with better fluidity. Taking advantage of the property that epoxy resin is not miscible with water, it is dispersed into polyacrylamide aqueous solution by stirring, and the dispersed epoxy resin forms liquid beads. After a certain period of time, under the action of the curing agent, the molecules of the resin are gradually exchanged, and the bead-like resin becomes a viscoelastic ball. The polyacrylamide aqueous solution is not only the dispersion medium for epoxy resin balls, but also the carrier liquid for sending the resin balls into the blast hole. During the injection process, the carrier fluid enters the oil layer, and the resin pellets are filtered and accumulated in the blasthole. Under the action of pressure, the viscoelastic pellets are compacted and further solidified with time, forming a hard plug in the blasthole And the blast hole is blocked, so as to achieve the purpose of water blocking.

In order to prevent the epoxy resin from agglomerating and sinking during the pelletizing process, the water used is tackifying water, that is, 0.8 to 1.2 (weight)% of polyacrylamide is dissolved in the water, so that the solution viscosity reaches (4 ~5)×10 ³ mPa·s, this polyacrylamide aqueous solution is called dispersion medium when making pellets.

The composition and content ratio of the resin pellets are as follows: 100 grams of epoxy resin, 15 to 25 milliliters of dibutyl phthalate, 20 to 35 milliliters of ethylenediamine, 0.8 0.8 milliliters of polyacrylamide aqueous solution of 0.8 to 1.2 (weight) % ~1.5 kg.

The above epoxy resin is the main ingredient; dibutyl phthalate is a softener, which can increase the toughness and bonding ability of the resin ball; ethylenediamine is a curing agent.

The formation of resin balls requires a certain temperature. When the temperature is lower than 20°C, the ball forming time is too long (more than 24 hours). When it is higher than 45°C, it is not conducive to operation, and the viscosity of the dispersion medium decreases, which affects the formation of beads. It is advisable to control the pelletizing temperature at 30-45°C.

The main factor affecting the particle size of the pellets is the ratio of the resin to the dispersion medium. The test results show that within a certain range, the larger the ratio of the resin to the dispersion medium, the larger the particle size of the pellets. At 35°C, under the condition that the viscosity of the dispersion medium is 4×10 ³ mPa·s, the particle diameters of the pellets formed by different proportions are as follows: dispersion medium (kg) epoxy resin (kg) pellet diameter (mm)

10 0.8 ＜1

10 1.0 1～2

10 1.2 2～4

10 1.5 4～6

In the above proportions, that is, when the dispersion medium is 10 kg, the epoxy resin is 0.8-1.5 kg, and the particle size of the ball is <1 mm to 4-6 mm, all are suitable for plugging blastholes.

About the control of gelation and curing time. The main factors affecting the gelation and curing time are the ambient temperature and the amount of curing agent. When the ambient temperature is constant, the amount of curing agent can control the gelation and curing time. The gelation and curing time at different curing agent dosages are given below at 35°C:

Epoxy resin grams dibutyl fat milliliters ethylenediamine milliliters gelation time hours, curing time hours

100 20 20 10 48

100 20 25 8 32

100 20 30 7 14

100 20 35 6 9

Note: 1. Gel forming time--the time from the addition of the curing agent to the time when the resin starts to form viscoelastic particles from liquid beads; 2. Curing time--the time from the addition of the curing agent to the time when the resin becomes solid particles.

The resin pellets are injected into the blasthole between gelation and before curing. If the injection is too early, the resin will squeeze into the oil layer due to its fluidity, and cannot form an embolism in the blasthole; if it is injected too late, the resin will become solid particles, lose its bonding ability, and cannot form an embolism in the blasthole.

About the preparation method of resin bead of the present invention is as follows:

1) Prepare polyacrylamide aqueous solution according to the dosage, the concentration is 0.8-1.2 (weight)%, and the viscosity is (4-5)×10 ³ mPa·s;

2) Select the ratio of epoxy resin, dibutyl phthalate and ethylenediamine according to the construction time requirements, and mix 15-25ml of dibutyl phthalate and ethylenediamine for every 100 grams of epoxy resin 20-35 ml to make epoxy resin composition;

3) Slowly add the prepared epoxy resin composition into the stirred prepared polyacrylamide aqueous solution to disperse it evenly;

4) Put the prepared composition solution into a constant temperature box (35-45°C), observe the condition of the pellets regularly, and when the viscoelastic pellets are formed, they can be carried by the polyacrylamide aqueous solution and injected into the oil well.

In order to verify the practicability of the present invention, a simulation test of plugging a blasthole was done. Oil well blasthole is a hole formed by shooting through the metal casing and the cement fixing the casing with high-energy perforating bullets. It is the throat for fluid to flow from the oil layer to the oil well. Accompanying drawing 1 is the schematic view of oil well blast hole, wherein, 1 is casing, 2 is cement, 3 is oil layer, 4 is blast hole, 5 is oil well. Following the structure of the above-mentioned oil well, a simulation test device for blasthole plugging was designed, as shown in Figure 2. Among them, 11 is the simulated casing and storage tank, 12 is cement, 13 is cemented quartz sand, used as simulated oil layer, 14 is blast hole, φ10×100 mm, 15 is carrier liquid plus resin ball, 16 is filtered through oil layer carrier fluid. The simulated blast hole 14 among the figure is to use an inner diameter of 32 millimeters and a metal pipe of 200 mm long, with the built-in cemented quartz sand replacing the oil layer, one end is filled with cement, and a φ 10 × 100mm hole is drilled to replace the blast hole. The simulated blast hole 14 is connected with the simulated casing 11 with a screw. When pressurizing the simulated casing 11 storing the resin pellets, the resin pellets are brought into the blast hole by the liquid, and the carrier fluid flows out through the simulated oil layer and flows into the container.

About the construction procedure of oil well blasthole plugging. Figure 3 shows the schematic diagram of oil well structure and plugging construction. Among them, 31 is the tubing, 32 is the packer, 33 is the distribution device, 34 is the check valve, 35 is the casing, 36 is the blast hole, 37 is the casing gate, 38 is the tubing gate, 39 is the pipeline, 40 is Pump car, 41 is to push away the liquid tank car, 42 is a water tank car, 43 is a resin ball storage pipe, 44 is a feeder, 45 is a plugging layer, and 46 is an oil outlet layer (protective layer).

The construction procedures for plugging blastholes are:

1) A pipe string for plugging blast holes is run into the oil well, and the pipe string is composed of oil pipe 31 , packer 32 , distribution device 33 , and one-way valve 34 .

2) The oil pipe 31 is pressurized to expand the packer 32 and seal the annular space of the oil casing;

3) salvaging the core in the distribution device 33, the distribution device can be communicated with the layer to be blocked;

4) Resin pellets are loaded into the storage tube 43;

5) Use a pump truck 40 to inject a certain amount of 0.8-1.2 (weight)% polyacrylamide aqueous solution into the oil well to carry the resin pellets into the pipeline, and then use the solution to send the resin pellets to the plugging layer. Throughout the injection process, the fluid enters the formation, and the ball plugs the borehole. Keep the pressure at 15Mpa and close the well for 24 hours until the pellets are compacted and solidified.

6) The construction string is replaced with a production string, and the oil well is transferred to normal production.

The plugging agent of the invention can save a large amount of plugging agent because it only plugs blastholes, and can meet the production requirements of oil wells with large pressure difference after plugging. The construction process is simple and easy to popularize.

Claims (2)

1. A kind of oil well blasthole resin pellet plugging agent, it is characterized in that: the composition of said plugging agent and content ratio are as follows: 100 grams of epoxy resins, 15～25 milliliters of dibutyl phthalates, dibutyl phthalate 20-35 milliliters of amine, 0.8-1.5 kilograms of 0.8-1.2 (weight)% polyacrylamide aqueous solution. 2. the manufacture method of the said oil well blast hole resin pellet plugging agent as claimed in claim 1 is characterized in that: a) prepare polyacrylamide aqueous solution by consumption, its concentration is 0.8～1.2 (weight) % viscosity is (4～ 5)×10 ³ mPa·s; b) Select the ratio of epoxy resin, dibutyl phthalate and ethylenediamine according to the construction time requirements. For every 100 grams of epoxy resin, add 15-25 ml of dibutyl phthalate, ethylenediamine 20-35 ml to make epoxy resin composition; c) slowly adding the prepared epoxy resin composition into the prepared polyacrylamide aqueous solution which is being stirred, so as to make it uniformly dispersed; d) Put the prepared composition solution into a constant temperature box at 35-45°C, observe the condition of the pellets regularly, and inject them into the oil well when the viscoelastic pellets are formed.

Images