Foamed acid washing technological method for horizontal well

Abstract

The invention provides a foamed acid washing technological method for a horizontal well. With two packers at a horizontal well segment installed and foamed acid washing liquid poured from an annulus, the acid liquid flows outside a sieve tube, thereby enhancing the flushing and unclogging effects on mud cakes of a drilling well. With the temporary clogging effect of foam on a high permeability position and the low density characteristic of the foam used, the acid liquid leakage can be effectively reduced; and at the same time, with the high carrying capacity of foamed liquid and the expansion energy of nitrogen gas used, acidized solid particles and residual acid can flow back, thereby avoiding the secondary sedimentation damage, solving the problems of acid liquid leakage and incomplete residual acid backflow in the conventional acid washing process, and effectively improving the acid washing effect. In the technological method, the reaction between the foamed acid washing liquid and the mud cakes of the drilling well is carried out in two steps: firstly, displacing the foamed acid washing liquid to the horizontal well segment, and shutting the well for reaction; and then, displacing the unreacted foamed acid washing liquid to the horizontal well segment, inversely squeezing the foamed acid washing liquid into the stratum, and shutting the well for reaction. The invention is especially suitable for relieving the well drilling damage of a low-pressure leakage horizontal well.

Description

Technical field: [0001] The invention relates to a method for removing pollution from horizontal well drilling, in particular to a process using foam pickling. Background technique: [0002] During the drilling and completion of horizontal wells, the drilling fluid and completion fluid will inevitably contact the oil and gas layers for a long time and in a large area, and its solid and liquid phases will enter the formation around the well wall, forming a large-scale pollution zone , which increases the seepage resistance of the fluid in the formation, causing more serious damage to the oil layer than the vertical well, resulting in unsatisfactory production effects of some horizontal wells. The main types of damage in horizontal wells are: drilling fluid solid phase immersion, mud cake damage to the reservoir, mud cake damage on the screen, damage to the reservoir caused by drilling fluid filtrate, formation damage caused by clay swelling and particle migration clogged. T...

AI Technical Summary

Problems solved by technology

Therefore, horizontal wells are also faced with the problems of pickling, plugging and pollution removal, dredging of seepage channels near the wellbore, and recovery and improvement of oil and gas well productivity. Conventional horizontal well pickling technology has the following problems: serious acid leakage, acid mainly High-permeability parts or the heel of the horizontal section; the property of the reservoir in the horizontal well section changes greatly, which increases the amount of acid used; for low-pressure formations, the residual acid flowback effect is poor, and precipitation is easy to form, causing secondary pollution, so it is considered to use Foam Pickling Technology

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