Five-step bullheading method for well killing in fractured formation without safe pressure window.

Abstract

The invention relates to the technical field of drilling well control, and discloses a five-step bullheading method for well killing in fractured formation without a safe pressure window. The well killing method comprises the steps that based on physical property parameters of intruding gas and physical property parameters of a well killing fluid, the well killing fluid is controlled to be discharged into an annulus between a sleeve of the well killing device and a drill string at a first discharge amount, so that the intruding gas is made to move downwards through the well killing fluid; thepressure of the well killing fluid at the well mouth in the annulus is detected and sent; when it is monitored that the pressure of the well killing fluid at the well mouth in the annulus keeps unchanged, it is determined that the intruding gas is completely pushed back into the stratum, the well killing fluid is controlled to stop being injected, and the drill string is controlled to move upwardsat a preset speed; in the process that the drill string moves upwards, based on the rising speed of the drill string, the well killing fluid is controlled to be discharged into the annulus at a second discharge amount, so that the pressure of the well bottom is kept to be constant. By means of the method, the safety risk generated in well killing process of the fractured formation without the safe pressure window can be greatly reduced, and therefore, a safety guarantee is provided for well killing operation.

Description

technical field [0001] The invention relates to the technical field of drilling well control, in particular to a well killing method and equipment for fractured formations without a safe pressure window. Background technique [0002] With the development of the economy, China's demand for oil and gas resources is also increasing. However, because most of the early major oil fields are in the middle and late stages of development and crude oil production is difficult to make a major breakthrough, China's dependence on foreign oil and gas has repeatedly hit new highs in recent years. Therefore, China's oil and gas exploration and development are gradually developing towards complex formations that were not paid much attention in the early stage, such as fractured formations. At present, the number of fractured reservoirs drilled in China is gradually increasing. The proven geological reserves of fractured oil and gas reservoirs account for 28% of the total proven reserves in C...

AI Technical Summary

Problems solved by technology

However, for gas invasion during drilling in fractured reservoirs without a safe pressure window, if these conventional well killing methods are used to kill wells, it is very easy to lead to the coexistence of leakage after pressure and blowout after leakage. Not only can it not effectively solve the problem of gas invasion or blowout, it may even damage the reservoir and affect the efficiency of oil and gas resource extraction

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