Solid-free slurry-replacing well completion protective fluid and preparation method thereof

Abstract

The invention discloses a solid-free slurry-replacing well completion protective fluid and a preparation method thereof, which belongs to the technical field of exploitation of oil and gas fields. The completion protective fluid comprises, by weight, 100 parts of a formate-based liquid, 0.2 to 0.4 part of a thickening agent, 1 to 3 parts of a high temperature high temperature, 0.2 to 3 parts of a clay stabilizing agent and 0.2 to 1 part of a waterproof locking agent. The completion protective fluid has the following advantages: (1) the completion protective fluid has no solid phase, so solid phase settlement does not exist; (2) the completion protective fluid has good rheological properties and a low shearing force value; (3) the completion protective fluid has an excellent hydrocarbon reservoir protection function; (4) the completion protective fluid has good high temperature resistance and salt resistance stability, and a system has good displacement and carrying capability under reservoir temperature; (5) the completion protective fluid is safe, nontoxic, easily degradable and compatible with the environment; (6) the completion protective fluid has good compatibility with a drilling fluid and a fracturing fluid, and the rheological properties of the completion protective fluid are not influenced after mixing; (7) the completion protective fluid has little corrosivity and greatly reduces corrosivity of a saline solution to downhole tools; and (8) the completion protective fluid has great specific gravity and no solid phase and is applicable to areas with abnormal high temperature and high-pressure area.

Description

technical field [0001] The invention specifically relates to a solid-free mud replacement well completion protection fluid for tight sandstone oil and gas wells, and also relates to a preparation method of the mud replacement well completion protection fluid, which belongs to the technical field of oil and gas field exploitation. Background technique [0002] Tight sandstone oil and gas is a typical unconventional oil and gas resource stored in low-permeability-ultra-low-permeability tight sandstone reservoirs. It is difficult to develop by conventional technology, and economic development can only be achieved through horizontal well + staged fracturing completion technology value. At present, tight sandstone oil and gas has become the main component of domestic oilfield exploration and development. [0003] Most domestic tight sandstone horizontal wells adopt the open-hole external packer + ball-sliding sleeve staged completion process. This completion process can realize ...

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Problems solved by technology

[0004] Domestic oilfields generally use conventional brine systems to replace drilling fluids in the field application process. The main problems are as follows: (1) Poor salt resistance and limited density adjustment range, which cannot meet the well killing needs of high-pressure reservoirs; (2) The system does not High temperature resistance, unstable system performance under high temperature conditions; (3) Poor displacement and carrying capacity; (4) Strong corrosion to casing and downhole tools; (5) Compatible with reservoirs, reservoir fluids and fracturing fluids Poor performance, easy to cause damage to the reservoir

[0005] Chinese patent (notification number: CN101230259B) discloses a high-temperature, salt-resistant, solid-free environmental protection drilling and completion fluid, which has many types of additives and a large amount of additives. The protection is not enough, and the damage to the reservoir is greater; the relative expansion rate of the product disclosed in the patent (Notice No.: CN101230259B) is only ≤20%, while the density of the product disclosed in the patent (Notice No.: CN101230259B) is only 1.20 g / cm 3

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