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CN-122012068-A - Ultralow-density propping agent for increasing yield of coalbed methane as well as preparation method and application thereof

CN122012068ACN 122012068 ACN122012068 ACN 122012068ACN-122012068-A

Abstract

The invention relates to the technical field of coalbed methane yield increase, in particular to an ultralow-density propping agent for coalbed methane yield increase as well as a preparation method and application thereof. The preparation method comprises the following steps of S1, ball milling kaolin and ferric oxide, drying and sieving to obtain powder, S2, dissolving polyethersulfone in N-methylpyrrolidone to form PES/NMP solution, adding the PES/NMP solution into the powder for multiple times, performing ultrasonic dispersion and stirring to obtain slurry, S3, dropwise dripping the slurry into deionized water through a needle head with the diameter of 0.2mm, rapidly solidifying and granulating, standing, drying to obtain a ceramic proppant sintering blank, and S4, sintering the ceramic proppant sintering blank to obtain the ultralow-density proppant. The ultralow-density propping agent for increasing the yield of the coalbed methane, which is prepared by the invention, has low density, can be carried and conveyed by clear water or brine, avoids the chemical dosage consumed by preparing the gel, does not contain residues, does not block stratum, reduces the pollution to underground water and environment, and simultaneously increases the fracturing efficiency and reduces the fracturing cost.

Inventors

  • MA RUI
  • CHEN ZHAOYING
  • LI YAO
  • ZHANG YUNJIE
  • HUANG XIAOTING
  • Shan qian
  • DING WEIMING
  • Zou Jingfan

Assignees

  • 中国地质大学（武汉）
  • 易安蓝焰煤与煤层气共采技术有限责任公司

Dates

Publication Date
20260512
Application Date
20251224

Claims (10)

  1. 1. The preparation method of the ultralow-density propping agent for increasing the yield of the coalbed methane is characterized by comprising the following steps of: s1, ball milling, drying and sieving kaolin and ferric oxide to obtain powder; s2, dissolving polyether sulfone in N-methyl pyrrolidone to form PES/NMP solution, adding the PES/NMP solution into powder for multiple times, performing ultrasonic dispersion, and stirring to obtain slurry; s3, dropwise adding the slurry into deionized water through a needle head with the diameter of 0.2mm, rapidly solidifying and granulating, standing, and drying to obtain a ceramic proppant sintering blank; And S4, heating the sintered ceramic proppant blank to 400-500 ℃ in a muffle furnace at a heating rate of 10-20 ℃ per minute, preserving heat for 1-2 hours, heating to 1300-1500 ℃ at a heating rate of 5-10 ℃ per minute, preserving heat for 1-2 hours, and cooling the sample along with the furnace to obtain the ultralow-density proppant.
  2. 2. The preparation method according to claim 1, wherein in the step S1, the mass of the iron oxide is 2.5% to 15% of the mass of the kaolin.
  3. 3. The method of claim 1, wherein in step S1, a 200 mesh sieve is used.
  4. 4. The process according to claim 1, wherein in step S2, the mass ratio of polyethersulfone to N-methylpyrrolidone is 1:6 and the mass ratio of PES/NMP solution is 8-10:35.
  5. 5. The method according to claim 1, wherein in step S3, the needle is positioned at a height of 10-20cm from the water surface, and the drop discharge rate is 3 drops/S.
  6. 6. The method according to claim 1, wherein in step S3, the drying temperature is 60 to 80℃and the drying time is 8 to 12 hours.
  7. 7. An ultra-low density proppant for stimulating coal bed gas produced by the method of any one of claims 1-6.
  8. 8. A proppant microcapsule for increasing yield of coal bed methane, which is characterized by comprising the ultralow-density proppant for increasing yield of coal bed methane according to claim 7, a methanogenic microbial agent loaded on the proppant microcapsule and a calcium alginate film coated on the surface of the methanogenic microbial agent.
  9. 9. A method for preparing the propping agent microcapsule for increasing the yield of the coal bed gas according to claim 8, wherein the propping agent microcapsule for increasing the yield of the coal bed gas is prepared by immersing the propping agent for increasing the yield of the coal bed gas in methanogenic bacteria liquid for a period of time, taking out, putting the propping agent into calcium lactate solution, gradually dropwise adding sodium alginate solution, and drying after coating is finished.
  10. 10. The preparation method according to claim 9, wherein the mass concentration of the sodium alginate solution is 25mmol/L, the mass concentration of the calcium lactate in the calcium lactate solution is 90mmol/L, the coating times are 3-5 times, and the single coating time is 1-5 minutes.

Description

Ultralow-density propping agent for increasing yield of coalbed methane as well as preparation method and application thereof Technical Field The invention relates to the technical field of coalbed methane yield increase, in particular to an ultralow-density propping agent for coalbed methane yield increase as well as a preparation method and application thereof. Background Coalbed methane is an important unconventional natural gas resource, and efficient development of the coalbed methane has important significance for relieving energy pressure. However, coalbed methane reservoirs have unique "three low one high" characteristics, namely low gas saturation, low permeability, low reservoir pressure, and high deterioration, which makes coalbed methane production a significant challenge. In order to improve the productivity of coal gas wells, hydraulic fracturing technology has become a primary means of coal bed gas reservoir reformation, the core of which is to enhance the desorption and migration of coal bed gas by creating and maintaining high conductivity fractures in the reservoir. In conventional hydraulic fracturing processes, proppants (e.g., quartz sand, ceramic grains, or precoated sand) are typically used to fill the fracture, preventing it from reclosing at closure pressure, thereby maintaining the fracture's conductivity. However, these proppants generally have the problems of high density and poor suspension performance, so that the proppants must be transported by means of high-viscosity sand-carrying fluids (such as water-based polymer fracturing fluids represented by guanidine gum) in fracturing construction. Although the high-viscosity sand-carrying fluid can improve the carrying capacity of proppants, a series of negative effects can be brought: 1. The risk of injury of the reservoir is increased, and the coalbed methane reservoir has a double pore structure (matrix pores and fracture pores) and is extremely sensitive to external conditions. The high molecular polymer and other organic additives in the high-viscosity sand-carrying fluid are easy to invade micro-pores and cracks, so that physical blockage or chemical adsorption is caused, the permeability of a reservoir is reduced, and the desorption and seepage of the coal bed gas are affected. 2. The fracturing cost is increased, the preparation and the use of the polymer sand-carrying fluid increase the material cost and the construction complexity, and the subsequent treatment (such as flowback and disposal) can further increase the exploitation cost. 3. The environmental and technological problems are that the polymer fracturing fluid is difficult to reverse discharge and is easy to stay in a reservoir to cause long-term pollution, and in addition, the high-viscosity fluid is difficult to completely reverse discharge in a low-pressure coal seam, so that the damage to the reservoir is further aggravated. In the prior art, while attempts have been made to improve the transport properties of proppants by optimizing their particle size, shape or surface modification, the high density nature of the proppants has not been altered and still relies heavily on highly viscous sand-carrying fluids. At the same time, fracturing fluids tend to simplify the use of additives, particularly to avoid organic polymeric materials, in order to reduce reservoir damage, but this is in contradiction with the need for proppant suspension transport. Therefore, how to realize the effective transportation of propping agent and the maintenance of the long-term diversion capability of the crack on the premise of not depending on high-viscosity sand-carrying fluid becomes a key difficult problem in the coalbed methane hydraulic fracturing technology. There is a need to develop a novel proppant material or fracturing process which is low in damage and cost and can adapt to special geological conditions of a coal bed so as to balance the relation between reservoir protection and fracturing effect, and promote the development of coal bed methane exploitation technology to an efficient and environment-friendly direction. In recent years, microbial stimulation techniques have received attention as an emerging green stimulation method. The technology utilizes the metabolic activity of the specific functional microorganisms injected into the reservoir to realize the following yield increasing mechanism that 1) methane is biologically generated, organic matters which are difficult to degrade in the coal are converted into methane, a gas source is added, 2) the biological acid is used for unblocking, the organic acid generated by metabolism can dissolve mineral matters in the coal, the pore throat is enlarged, 3) the biological surfactant is used for changing the wettability of coal and rock, the adsorption energy of the methane is reduced, and the desorption is promoted. However, the existing microorganism yield increasing technology has many challenges in application, such a