Filtrate loss reducer and application thereof to non-tackifying pure liquid-state CO2 sand fracturing

Abstract

The invention discloses a filtrate loss reducer. The filtrate loss reducer is prepared from the following raw materials in parts by weight: 10-25 parts of 5# white oil, 0.5-2 parts of NP-1, 0.1-1 part of TX-4, 1-10 parts of n-caprylic acid, 1-10 parts of KCl, 4-15 parts of a carboxymethyl guanidine gum solution with the concentration of 1%. According to the filtrate loss reducer, the sand carrying capability of pure liquid-state CO2 fracturing liquid can be improved and the loss of the fracturing liquid is effectively reduced. Meanwhile, the invention further provides application of the filtrate loss reducer to a pure liquid-state CO2 sand fracturing process; the filtrate loss reducer is pumped into a stratum before pure liquid-state CO2 fracturing is constructed, and the sand fracturing is carried out; the filtrate loss reducer has the advantages of rapid backflow, increased backflow rate, shortened period of putting into production and the like; and water-based fracturing liquid does not need to be prepared in the process and backflow liquid does not need to be treated, so that the environment pollution degree is reduced, and the filtrate loss reducer has relatively good practical significance on regions with lacked water resources and regions with fragile ecological environments.

Description

technical field [0001] The invention belongs to the technical field of petroleum fracturing, in particular to a fluid loss reducer and its non-viscosifying pure liquid CO 2 Applications in sand fracturing. Background technique [0002] In China, unconventional oil and gas resources such as low permeability and ultra-low permeability are abundant. However, because the physical properties of unconventional reservoirs are generally poor, it is necessary to use reservoir stimulation technology to improve seepage conditions in order to achieve the purpose of effective production. [0003] The most commonly used reservoir stimulation technology is hydraulic fracturing technology, which uses water-based fracturing fluid to stimulate the reservoir. The hydraulic fracturing technology has problems such as large water consumption, damage to the reservoir by fracturing fluid residues, and incomplete flowback. defect. For example, the current fracturing method used in shale gas wells...

AI Technical Summary

Problems solved by technology

This type of hydraulic fracturing technology mainly has the following two defects: first, a large amount of water entering the reservoir will cause clay minerals to expand, disperse and migrate, resulting in reduced permeability and clogged pores; second, the huge water consumption makes fracturing difficult. The fluid flowback speed and flowback efficiency are low, and the fracturing effect is poor

However, in the pre-acid treatment in this process, the acid liquid is squeezed out. The acid liquid will cause corrosion of the fracturing equipment and increase the cost. Moreover, when the fracturing fluid is not completely flowed back, the residual acid liquid will cause certain damage to the reservoir. damage

[0007] Chinese application (CN 103924955 A) discloses a fracturing process using liquid CO 2 After initial fracturing, slick water is used for fracturing. Although the flowback period is shortened, this process still has the disadvantage of high water consumption, and the early acid treatment will cause certain losses to the equipment.

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