A kind of compound unblocking method

Abstract

The invention relates to a composite unblocking method. The method includes the following steps: rotary-spraying for cleaning, namely forward squeezing cleaning liquid through a continuous oil pipe arranged inside an oil pipe, and performing rotary-spraying to clean a screen pipe through a rotary-spraying nozzle arranged at the bottom end of the continuous oil pipe; forward squeezing foam of the oil pipe; allowing to the oil pipe to flow out; flowing back with negative pressure; when reversing-out pressure of an oil well during flowing-out of the oil pipe is lower than 5MPa, injecting 0.3-0.6g / cm3 of foam or 900-1500m3 / h of nitrogen through the continuous oil pipe to realize continuous downhole negative pressure. The composite unblocking method is applicable to the technical field of scree pore unblocking of a sand-preventive pipe column, high-pressure rotary spraying can be effectively utilized to generate strong impact force and chemical agent dissolving, diffusing and cleaning effect to enable plugs at pores of a sand-preventive screen pipe or areas close to a well to be smashed and shed, and formed particles can be discharged through the pores of the screen pipe during foam negative pressure flowback.

Description

technical field [0001] The invention relates to the technical field of screen blockage cleaning of sand control pipe strings in the oil recovery process, in particular to a composite plugging removal method. Background technique [0002] At present, in the process of oil exploitation, sand control is an indispensable link in the development of sand producing oil and gas reservoirs, and screen sand control is the most commonly used oil well sand control method in today's oil fields. After the oil well has been in production for a period of time, the blockages such as fine sand, shale and bituminous colloid in the formation fluid, and solid particles remaining in the drilling fluid will block the screen and the annular sand layer outside the screen, causing oil well failure. Blockage, the output is seriously reduced. Among them, the oil reservoirs in the Bohai Bay area are mostly unconsolidated sandstone heavy oil reservoir structures, the reservoirs are loosely cemented, and...

AI Technical Summary

Problems solved by technology

Foam negative pressure mixed drainage plugging removal uses foam huff and puff and negative pressure mixed drainage, relying on the strong ability of foam to carry particles and the large bottom hole pressure difference, the blockages such as solid particles and organic sediments near the wellbore area are discharged out of the formation, but for For wells with clogged sand control screens, the effect of this process is not good. The main reasons are: the clogged sand control screens make the foam fluid mainly enter and flow back along the unplugged screen holes during operation, and the screens and near-wellbore areas are clogged It cannot be completely removed; limited by the sand-retaining precision of the sand control screen, large particle blockages cannot be discharged

[0005] In summary, the solutions in the prior art have the above-mentioned many defects, and cannot effectively solve the above-mentioned composite blockage

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