Expansion leaking stoppage particle and leaking stoppage material

Abstract

The invention discloses an expansion leaking stoppage particle and a leaking stoppage material.The expansion leaking stoppage particle is prepared from, by weight, 35-50 parts of hydrogenated butadiene-acrylonitrile rubber, 10-20 parts of trimethylolpropane trimethacrylate, 5-8 parts of nickel dibutyl dithiocarbamate and 15-18 parts of a cross-linking agent. The cross-linking agent is 1, 3-bis (tert-butylperoxy) isopropyl benzene or 1, 4-bis (tert-butylperoxy) isopropyl benzene, and the cross-linking agent is 1, 3-bis (tert-butylperoxy) isopropyl benzene. The leaking stoppage material comprises the expansion leaking stoppage particles, and the expansion leaking stoppage particles are formed by mixing coarse particles and fine particles; the ratio of the coarse particles to the fine particles is 1: 1. The particle size of the coarse particles ranges from 1 mm to 3 mm, and the particle size of the fine particles ranges from 100 micrometers to 250 micrometers. After expansion, shot hole gaps can be rapidly filled, a compact leaking stoppage layer is formed, the surfaces of the particles can generate chemical adsorption with stratum rocks, the leaking stoppage effect is enhanced, and the expanded particles have high mechanical strength and can effectively support stratum pressure and prevent leakage.

Description

Technical Field

[0001] The present invention relates to the field of plugging materials, and specifically refers to an expandable plugging granule and a plugging material. Background Art

[0002] In the process of oil exploitation, due to the continuous development of exploitation technologies and equipment, along with the continuous research and re-understanding of geological conditions, in China, the development of deeper and denser producing formations has become an important means to increase oil and gas equivalent in recent years.

[0003] Globally, with the continuous growth of global energy demand and the increasing depletion of conventional oil and gas resources, the development of unconventional oil and gas resources has gradually become an important research direction in the energy field. As an effective formation stimulation method, hydraulic fracturing technology plays a key role in increasing oil and gas production and recovery rate. Since its first application in oil and gas field development in the mid-20th century, hydraulic fracturing technology has undergone decades of development and improvement and has now become one of the core technologies for the development of unconventional oil and gas resources.

[0004] After the introduction of fracturing technology in China at the beginning of this century, the reuse and redevelopment of some low-yield wells in old oilfields have become an important topic in recent years. Developing old wells has natural advantages: 1) There is no need to acquire land to find new well positions, greatly saving development space; 2) There is no need to drill new wells, only need to deepen the wellbore to the new target producing formation, greatly saving development time; 3) The surface facilities of old wells are complete, and production can directly start after development, greatly saving development costs and development cycle.

[0005] However, in the redevelopment of old wells, the plugging of perforation holes in the developed producing formations has become a key technical problem because high-pressure hydraulic fracturing needs to be carried out on the new producing formations after plugging, so there are high requirements for pressure resistance. Traditional plugging methods such as cement slurry and chemical plugging agents, although they can solve problems to a certain extent, their plugging effects are unstable and there are certain limitations. Summary of the Invention

[0006] The purpose of the present invention is to solve the above problems, and provides an expandable plugging granule and a plugging material.

[0007] The purpose of the present invention is achieved through the following technical solutions: An expandable plugging granule, comprising the following components in parts by weight:

[0008] 35 - 50 parts of hydrogenated nitrile rubber, 10 - 20 parts of trimethylolpropane trimethacrylate, 5 - 8 parts of nickel dibutyldithiocarbamate, and 15 - 18 parts of crosslinking agent.

[0009] The crosslinking agent is 1,3-bis(tert-butylperoxy)cumene or 1,4-bis(tert-butylperoxy)cumene.

[0010] The present invention also discloses a plugging material, including the above-mentioned expandable plugging particles, and the expandable plugging particles are composed of a mixture of coarse particles and fine particles; the ratio of the coarse particles to the fine particles is 1:1.

[0011] The particle size of the coarse particles is 1-3 mm, and the particle size of the fine particles is 100-250 μm.

[0012] Compared with the prior art, the present application has the following beneficial effects: After expansion, the expandable particles of the present invention can quickly fill the gaps in the boreholes to form a dense plugging layer, and the surface of the particles can chemically adsorb with the formation rocks to enhance the plugging effect. The expanded particles have high mechanical strength and can effectively support the formation pressure to prevent leakage. Description of the Drawings

[0013] The drawings described herein are used to provide a further understanding of the present application, and constitute a part of the present application. The schematic embodiments and descriptions thereof of the present application are used to explain the present application and do not constitute a limitation to the present application. In each figure, the same reference numerals represent the same components. Among them,

[0014] Figure 1 is the expansion rate of the plugging material in Example 1 in each system at room temperature.

[0015] Figure 2 is the expansion rate of the plugging material in Example 1 in each system at room temperature and high salt content.

[0016] Figure 3 is the expansion rate of the plugging material in Example 1 in each system at high temperature.

[0017] Figure 4 is the expansion rate of the plugging material in Example 1 in each system at high temperature and high salt content.

[0018] Figure 5 is a schematic diagram of the plugging material in Example 1 embedded in the proppant. Detailed Embodiments

[0019] Example 1

[0020] The expandable plugging particles of this example include the following components in parts by weight:

[0021] 50 parts of hydrogenated nitrile rubber, 10 parts of trimethylolpropane trimethacrylate, 5 parts of nickel dibutyldithiocarbamate, 18 parts of crosslinking agent; among them, the crosslinking agent is 1,3-bis(tert-butylperoxy)cumene.

[0022] During preparation, the expandable plugging particles can be prepared into particles of different particle sizes. Mixing the large-particle-size expandable plugging particles and the small-particle-size expandable plugging particles together forms the plugging material. Among them, the ratio of the large-particle-size expandable plugging particles to the small-particle-size expandable plugging particles is 1:1. The particle size of the large-particle-size expandable plugging particles is 3 mm, and the particle size of the small-particle-size expandable plugging particles is 100 μm.

[0023] Example 2

[0024] The expandable plugging particles of this example include the following components in parts by weight:

[0025] 45 parts of hydrogenated nitrile rubber, 20 parts of trimethylolpropane trimethacrylate, 8 parts of nickel dibutyldithiocarbamate, 15 parts of crosslinking agent; among them, the crosslinking agent is 1,4-bis(tert-butylperoxyisopropyl)benzene.

[0026] During preparation, the expandable plugging particles can be prepared into particles of different particle sizes. Mixing the large-particle-size expandable plugging particles and the small-particle-size expandable plugging particles together forms the plugging material. Among them, the ratio of the large-particle-size expandable plugging particles to the small-particle-size expandable plugging particles is 1:1. The particle size of the large-particle-size expandable plugging particles is 2 mm, and the particle size of the small-particle-size expandable plugging particles is 250 μm.

[0027] Example 3

[0028] The expandable plugging particles of this example include the following components in parts by weight:

[0029] 35 parts of hydrogenated nitrile rubber, 15 parts of trimethylolpropane trimethacrylate, 7 parts of nickel dibutyldithiocarbamate, 17 parts of crosslinking agent; among them, the crosslinking agent is 1,4-bis(tert-butylperoxyisopropyl)benzene.

[0030] During preparation, the expandable plugging particles can be prepared into particles of different particle sizes. Mixing the large-particle-size expandable plugging particles and the small-particle-size expandable plugging particles together forms the plugging material. Among them, the ratio of the large-particle-size expandable plugging particles to the small-particle-size expandable plugging particles is 1:1. The particle size of the large-particle-size expandable plugging particles is 1 mm, and the particle size of the small-particle-size expandable plugging particles is 200 μm.

[0031] Perform an expansion performance test on the plugging material in Example 1:

[0032] During the fracturing process, the wellbore fluid often contains guar gum, xanthan gum, and HEC thickeners. Therefore, the plugging material in Example 1 is subjected to an expansion performance test in a guar gum system, a xanthan gum system, and an HEC thickener system at normal temperature, high temperature, and high salinity. The test results are as Figures 1-4As shown, in common fracturing systems, although high-temperature and high-salinity systems will affect the swelling rate of the plugging material to a certain extent, the swelling rate of the plugging material is above 50%, which does not affect the use performance of the particles. In addition, it should also be noted that during the actual on-site fracturing construction process, the plugging material is actually pre-pumped into the perforation fractures to be plugged, usually pumped in a fresh water system. The plugging material has already swelled and completed the plugging. During the subsequent operation process, the well may be contaminated with systems such as guar gum, xanthan gum, and HEC thickeners. However, the swelled plugging material can still play its role in these contaminated systems.

[0033] Conduct a pressure-bearing test on the plugging material in Example 1:

[0034] Experiment 1: Fill the plugging material in Example 1 in the experimental tool to make the plugging material fill the entire experimental cavity. Pump fresh water into the experimental tool to fully swell the plugging material. After 24 hours, conduct a pressure test. First, pressurize to 5000 psi. The pressure drop within 15 minutes is 0.18%. It is confirmed that the particles have swelled and combined. Next, directly increase the pressure to 10000 psi and keep the pressure stable for 30 minutes. The pressure drop is less than 1.5%. It can be concluded that the fully swelled and filled plugging material can withstand a high pressure of 10000 psi to meet the fracturing requirements at the construction site.

[0035] Experiment 2: Fill the plugging material in Example 1 on the left side of the experimental tool. Fill the common 40-mesh to 70-mesh fracturing sand in the right cavity of the experimental tool to simulate the situation where fracturing sand has been filled in many perforation channels. Then, continuously pump fresh water at a displacement of 1 bar from the left side to carry the swollen particles on the left side into the voids of the right-side fracturing sand. Then, take out the remaining swollen particles on the left side. The fracturing sand mixture with swollen particles embedded on the right side is left to swell for 24 hours. After 24 hours, conduct a pressure test. After keeping the pressure stable for 30 minutes, the pressure drop is less than 1%. This test shows that when the plugging material can enter the proppant matrix, it will combine with the proppant and aggregate together and can withstand a pressure of 10000 psi.

[0036] It can be seen from the experiments that the plugging material of the present application has reliable plugging performance. It is particularly suitable for plugging the pay zones developed after perforation, thus providing conditions for the refracturing development of new pay zones. The plugged channels can withstand a high pressure of 10000 psi without being damaged, which solves the technical problems encountered in the redevelopment stage of old wells. Even if the pay zones being developed have been filled with fracturing sand, the swollen particles can penetrate and distribute into their gaps to form an integrated matrix, as Figure 5 shown, which is more conducive to achieving the plugging effect.

[0037] It should be noted that all features disclosed in this specification, or steps in all methods or processes disclosed, can be combined in any way, except for mutually exclusive features and / or steps.

[0038] In addition, the above specific embodiments are exemplary. Those skilled in the art can come up with various solutions inspired by the disclosure of the present invention, and these solutions also fall within the scope of the disclosure of the present invention and within the protection scope of the present invention. Those skilled in the art should understand that the description of the present invention and its accompanying drawings are illustrative and do not constitute a limitation on the claims. The protection scope of the present invention is defined by the claims and their equivalents.

Claims

1. An expanding plugging particle, characterized in that, Comprising the following components in parts by weight: 35-50 parts of hydrogenated nitrile rubber, 10-20 parts of trimethylolpropane trimethacrylate, 5-8 parts of nickel dibutyldithiocarbamate, 15-18 parts of crosslinking agent.

2. The expandable plugging particle according to claim 1, wherein, The crosslinking agent is 1,3-bis(tert-butylperoxy)cumene or 1,4-bis(tert-butylperoxy)cumene.

3. A plugging material, characterized in that, Including the expandable plugging particles described in claim 1 or 2, the expandable plugging particles are formed by mixing coarse particles and fine particles; the ratio of the coarse particles to the fine particles is 1:

1.

4. The plugging material according to claim 3, characterized in that, The particle size of the coarse particles is 1-3 mm, and the particle size of the fine particles is 100-250 μm.

Images