Completion fluid used for removing filter cake formed by oil-based drilling fluid and preparation method thereof

Abstract

The invention provides a completion fluid used for removing a filter cake formed by an oil-based drilling fluid and a preparation method thereof. The completion fluid comprises, by weight, 85 to 92% of a base fluid, 2 to 4% of a main emulsifier, 2 to 3% of an auxiliary emulsifier, 1 to 3% of a mutual solvent and 3 to 5% of a high-efficiency blocking remover and can effectively remove the filter cake formed by the oil-based drilling fluid and protect a hydrocarbon reservoir.

Description

technical field [0001] The invention relates to a well completion fluid for petroleum drilling, in particular to a well completion fluid for removing oil-based drilling fluid filter cake and a preparation method thereof. Background technique [0002] Oil-based drilling fluid has the advantages of strong inhibition, strong anti-pollution ability, and protection of oil and gas layers. Therefore, it is often used in some complex formations that are water-sensitive and prone to collapse. However, the filter cake formed by oil-based drilling fluid can easily block the formation pores in the screen or near the wellbore, causing damage to the oil layer. In order to remove these filter cakes, the commonly used methods in China are mainly acid dissolution method and oxidation cracking method, etc., but these methods are mostly researched on water-based drilling fluid, and there are few researches on oil-based drilling fluid filter cake removal technology. Wang Fuhua et al. prop...

AI Technical Summary

Problems solved by technology

The disadvantages or deficiencies of these technologies are: ① A single acidification method is not effective in removing polymers. At the same time, a large amount of acid is required. Excessive acid can degrade the formation matrix and release fine particles, which will migrate and cause bridge plug, limiting capacity

②The components contain water phase, which is likely to cause pollution of oil-based drilling fluid and reduce its reuse efficiency; at the same time, it is easy to cause water lock damage in the oil layer

③During the well completion process, some processes require that the completion fluid be pumped first and then the screen pipe be run, so the mud cake must not be destroyed for a period of time before the screen pipe is run, but the demulsification speed of part of the clearing fluid is too fast to be guarantee this

④Many components and complex process increase the difficulty and cost of construction

⑤Used in a variety of drilling fluids, the pertinence is not strong, and the effect is likely to be unsatisfactory

⑥ Strong acid is used in part of the cleaning liquid, which is easy to cause corrosion of the screen tube

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