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Use of multi-arm star-shaped copolymer as diverting agent for fracturing and its preparation method

A copolymer and multi-armed star technology, which is applied in the field of multi-armed star-shaped copolymers as diverting agents for fracturing, can solve problems such as difficult dissolution and plugging, and achieve simple and feasible synthesis methods, mild reaction conditions, and high plugging strength high effect

Active Publication Date: 2018-07-13
BC P INC CHINA NAT PETROLEUM CORP +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The defect of this type of diverting agent is that it generally contains water-insoluble calcium carbonate, and the fracturing fluid used in conventional fracturing construction is alkaline, and post-treatment needs to be unblocked by perforating or acidizing processes; ( 2) Cross-linked gel breaking type diverting agent
At present, it is more suitable for oil wells in use, but it is difficult to achieve dissolution and plugging removal in gas wells or water-producing oil wells

Method used

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  • Use of multi-arm star-shaped copolymer as diverting agent for fracturing and its preparation method
  • Use of multi-arm star-shaped copolymer as diverting agent for fracturing and its preparation method
  • Use of multi-arm star-shaped copolymer as diverting agent for fracturing and its preparation method

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0030] Pour the glycolide (GA) monomer into a three-necked flask, heat the oil bath to 80°C to a molten state, vacuumize for 15 minutes while stirring (vacuum degree 1-2Torr), pass dry nitrogen, remove oxygen and moisture, add Trimethylolpropane initiator and stannous octoate catalyst, the temperature of the oil bath was raised to 150° C., and the reaction was continued for 8 hours to obtain a crude reaction product. Completely dissolve the reaction crude product in dichloromethane, then add excess ethanol to it, pour off the upper solvent to obtain a precipitate, dissolve the precipitate in dichloromethane, add excess ethanol again, collect the precipitate II again, and repeat the dissolution-precipitation process , to obtain the final product. The final product was vacuum-dried at room temperature for 48 hours to obtain a milky white three-armed star-shaped copolymer. In the preparation process of the three-arm star-shaped copolymer, the trimethylolpropane initiator account...

Embodiment 2

[0037] Mix the racemic lactide D, L-LA monomer with a molar concentration of 25% and the glycolide GA monomer with a molar concentration of 75% and pour it into a three-necked flask as a copolymerization raw material, and heat it in an oil bath to 80°C to a molten state, vacuumize for 15 minutes under stirring (vacuum degree 1-2 Torr), pass dry nitrogen, remove oxygen and moisture, add pentaerythritol initiator and stannous octoate catalyst, heat the oil bath to 150°C, and continue the reaction for 8 hours. The reaction crude product was obtained. Completely dissolve the reaction crude product in dichloromethane, then add excess ethanol to it, pour off the upper solvent to obtain a precipitate, dissolve the precipitate in dichloromethane, add excess ethanol again, collect the precipitate II again, and repeat the dissolution-precipitation process , to obtain the final product. The final product was vacuum-dried at room temperature for 48 hours to obtain a milky white four-arm ...

Embodiment 3

[0045] The racemic lactide D, L-LA monomer with a molar concentration of 50% and the glycolide GA monomer with a molar concentration of 50% are evenly mixed and poured into a three-necked flask as a copolymerization raw material, and the oil bath is heated to 80°C to the molten state, vacuumize for 15 minutes under stirring (vacuum degree 1-2Torr), pass dry nitrogen, remove oxygen and moisture, add pentapentyl alcohol initiator and stannous octoate catalyst, heat the oil bath to 150°C, and continue the reaction 8h to obtain the reaction crude product. Completely dissolve the reaction crude product in dichloromethane, then add excess ethanol to it, pour off the upper solvent to obtain a precipitate, dissolve the precipitate in dichloromethane, add excess ethanol again, collect the precipitate II again, and repeat the dissolution-precipitation process , to obtain the final product. The final product was vacuum-dried at room temperature for 48 hours to obtain a milky white five-...

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Abstract

The invention discloses a purpose of a multi-arm star copolymer used as a diverting agent for fracturing and a preparation method of the multi-arm star copolymer. According to the multi-arm star copolymer used as the diverting agent, any one of three-arm star poly lactic-glycolic acid, four-arm star poly lactic-glycolic acid, five-arm star poly lactic-glycolic acid and six-arm poly lactic-glycolic acid is used or several materials from three-arm star poly lactic-glycolic acid, four-arm star poly lactic-glycolic acid, five-arm star poly lactic-glycolic acid and six-arm poly lactic-glycolic acid are mixed to be used according to different particle sizes. The preparation method comprises the steps that racemic lactide or glycolide or a mixture of the racemic lactide and the glycolide is used as copolymerization raw materials to be added into a reaction vessel, and the raw materials are heated to a melted state; an initiating agent and a catalyst are added into the reaction vessel under the nitrogen gas protection, and the reaction is taken to obtain a crude product; the crude product is purified and dried to obtain the multi-arm star copolymer. The multi-arm star copolymer used as the diverting agent has the advantages that the sealing and plugging effect of a conventional diverting agent can be achieved; the automatic degradation and plug removal after fracturing or acid cracking can also be realized; the damage to a reservoir is little. The preparation method is simple, convenient and feasible; the reaction condition is mild; the final product can be prepared only through one-step reaction.

Description

technical field [0001] The invention belongs to the field of oil field exploitation, and in particular relates to the use of a multi-arm star-shaped copolymer as a diverting agent for fracturing and a preparation method thereof. Background technique [0002] The development of low-permeability oilfields has entered the middle and later stages, and refracturing has gradually become an important measure to stabilize production in low-permeability oilfields. In the refracturing operation, the old fractures are blocked by the bridging effect of the diverting agent, the bottom hole static pressure is increased, and a new fracture is formed in a different direction from the old fracture, thereby opening a new fluid flow channel in the reservoir. Widely connect undeveloped oil and gas layers in old fractures to increase oil and gas production. [0003] At present, the diverting agents suitable for oil field fracturing mainly include the following categories: (1) Calcium carbonate ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C09K8/68C09K8/508
CPCC08G63/08C08G63/85C09K8/5086C09K8/68C09K8/885
Inventor 邹鹏王林张世林姜有才李诗仙张建华
Owner BC P INC CHINA NAT PETROLEUM CORP