Seawater base fracturing fluid

Abstract

The invention relates to a seawater base fracturing fluid which comprises a seawater base fluid, a gel breaking agent equivalent to 0.1-0.8% of the weight of the seawater base fluid, and a cross-linking agent equivalent to 0.2-0.8% of the weight of the seawater base fluid, and is characterized in that the seawater base fluid comprises the following components in percentage by weight: 0.3-0.6% of a thickening agent, 0.1-1% of a discharge aiding agent, 0.5-3% of a clay stabilizing agent, 0.01-0.1% of a sterilizing agent and the balance being seawater; the gel breaking agent is ammonium persulfate or sodium persulfate; the cross-linking agent is aluminum chloride or zirconium acetate; the clay stabilizing agent is potassium chloride or ammonium chloride; the discharge aiding agent is dodecyltrimethylammonium bromide or cetyltrimethylammonium bromide; and the sterilizing agent is methanal or dodecyl dimethyl benzyl ammonium chloride. The seawater base fracturing fluid has the advantages that the salt tolerance of the seawater base fracturing fluid is outstanding and stable cross-linking can be achieved in a weak alkaline environment.

Description

technical field [0001] This patent belongs to the technical field of oil and gas field development and stimulation, and in particular relates to a seawater-based fracturing fluid. Background technique [0002] With the increasing development of offshore oil and gas fields, more and more high-quality reserves have been used, and the proportion of low-permeability reserves in undeveloped reserves has reached about 20%. In 2008, the crude oil output of offshore low-permeability oil and gas fields was 150×10 4 m 3 , the natural gas production is 4.1×10 8 m 3 , accounting for 4.3% and 3.8% of the total output respectively, far below the onshore level. Therefore, how to efficiently develop and produce offshore low-permeability reservoirs will be the key to achieving stable production of offshore oil and gas fields in the future, and it also has important strategic significance for maintaining my country's energy security. [0003] Hydraulic fracturing, as an important stimula...

AI Technical Summary

Problems solved by technology

In addition, the cost of synthetic polymers is higher than that of vegetable gums; the second type is clean fracturing fluid systems, which use surfactants as thickeners, and their temperature resistance is usually poor, generally less than 100°C; the third type It is a modified anionic guar gum fracturing fluid system (CN102618249). This system uses carboxymethyl and sulfonic acid guar gum as thickeners. Due to the polyelectrolyte effect of anionic guar gum in seawater, metal cations can interact with The anionic groups in the molecular chain of guar gum undergo electrostatic interaction and gather around the molecular chain, which not only causes the molecular chain to curl up, reduces the hydrodynamic volume and viscosity, but also prevents water molecules from penetrating into the polymer and reduces the swelling performance.

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