Well killing fluid and its preparation method

Abstract

The invention discloses a killing fluid and a preparation method thereof, belonging to the technical field of oil field workover. The killing fluid includes the following components in mass percentage: brine 61.6%-87.1%, alkaline scale inhibitor 1%-2%, oil-soluble temporary plugging agent 0.5%-1.0%, modified attapulgite 4%- 7%, calcium carbonate 7%-30%, wetting agent 0.2%-0.5%, and the balance is defoamer. The density of brine is 1.35~1.43g / cm 3 , and the brine contains calcium ions with a concentration of 14-19g / L. The density of alkaline scale inhibitor is 1.40g / cm 3 , The hydrogen ion concentration index is 13-14. The modified attapulgite is attapulgite processed by ultrasonic cavitation. By adding brine, alkaline scale inhibitor, modified attapulgite and cooperating with other components, the well killing fluid has high temperature resistance, high density, low corrosion, scale dissolution and scale inhibition, temporary plugging, It is easy to prepare, easy to operate and low in cost, and improves the safety in the process of killing wells. Moreover, after the well killing fluid is used for operation, the production recovery rate of oil and gas wells is above 90%, and at the same time, the well killing fluid self-decomposes and flows back with the negative pressure of the operation.

Description

Well killing fluid and preparation method thereof technical field The present invention relates to a kind of well kill fluid and preparation method thereof, belong to the technical field of oil field workover. Background technique [0002] In the oil field production and development process, in order to ensure the normal production of oil and gas wells, it is necessary to carry out workover operations on the oil and gas wells. In the workover operation, in order to balance the fluid pressure in the formation and ensure the safety of the workover operation, the density is usually 1.5g / cm 3 above The fluid is used as the killing fluid, and the killing fluid is used for the killing operation. At present, the commonly used density is 1.4g / cm 3 The above killing fluid is a sodium formate system killing fluid, which includes the following qualities Percentage of components: sodium formate 37.40%-44.21%, attapulgite 2.56%-3.46%, conditioner 1# 0.1% ~1%, Regulator 2#...

AI Technical Summary

Problems solved by technology

[0004] In the process of preparing the kill fluid of the sodium formate system, since sodium formate is solid, it is necessary to dissolve the solid sodium formate to prepare a sodium formate solution, but in the process of preparing the sodium formate solution, after adding the solid sodium formate to water, the volume of the water will increase. However, the volume increase is difficult to control and difficult to operate, resulting in a large difference between the final prepared killing fluid density and the required killing fluid density, affecting the well killing operation and posing safety hazards

In addition, the density of sodium formate solution is up to 1.35g / cm 3 , the highest density of the prepared sodium formate system kill fluid is 1.55g / cm 3 , it is impossible to prepare a higher density kill fluid

Moreover, the cost of sodium formate is relatively high, which increases the cost of well killing operations

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