Determination method of well killing occasion of pressing-back method for gas well

Abstract

The invention discloses a determination method of a well killing occasion of a pressing-back method for a gas well. The determination method of the well killing occasion of the pressing-back method for the gas well comprises the following steps of collecting the physical property parameters of a stratigraphic rock and a fluid through geological logging and the data of an adjoining well; drawing an IPR (Inflow Performance Relationship) curve of the gas well by a formula through the collected data; drawing an OPR (Outflow Performance Relationship) curve of a relationship between a pit shaft gas yield and bottom hole pressure; drawing the IPR curve and the OPR curve in the same coordinate system; calculating an allowable maximum well shut-in time; calculating a wellhead pressure function when the well killing is started at some moment after well shut-in; solving wellhead maximum pressure; judging latest time when the well killing is started. The method is applicable to the conditions that the circulating well killing cannot be carried out due to the well blowout of the gas well and the pressing-back method is adopted to carry out the well killing; the latest well killing time that the well is successfully killed by using the pressing-back method after the well shut-in can be calculated; therefore, the risk that wellhead pressure generated in a well killing process exceeds maximum allowable wellhead pressure can be removed; the theoretical guidance is provided for the success of the well killing. The method is uncomplicated in calculation process, simpler in operation technique, and suitable for field use.

Description

technical field [0001] The invention relates to a method for judging the timing of a well killing when the pressure-back method is adopted when drilling encounters a blowout in a gas layer or when the well cannot be killed by circulation, and belongs to the technical field of oil drilling well control. Background technique [0002] With the rapid growth of the national economy, my country's demand and dependence on oil and natural gas energy is increasing day by day. At present, the eastern oilfields have entered the late stage of development, the oil wells have high water content, and it is difficult to make a major breakthrough in crude oil production. In the future, the central and western oilfields will become the focus of drilling and development. Due to the high formation pressure and abundant natural gas resources in the western oilfields, well kicks, overflows and even blowouts are prone to occur during drilling. Conventional well killing methods such as conventiona...

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Problems solved by technology

[0005] In order to solve the problems existing in the pressure-back method when drilling into a high-pressure gas layer, the present invention proposes a method for selecting the timing of the pressure-back method of a gas well, which is especially suitable for drilling into a gas lay

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