Optimal Pressure Relief Mode During the Process of Stopping a Vertical Well
Year: 2025
Type: article
Abstract: The process of killing a vertical well by introducing a tubing pipe through which heavy fluid is supplied into the casing is considered. Filling of the inner pipe occurs without losses. Replacement of the oil phase from the annular space with the killing fluid supplied to the wellhead is of particular interest due to the losses at the bottomhole, which impede the advance of the displacement front and can be quite significant. The intensity of the escape of the supplied fluid into the formation depends on the value of the pressure at the bottomhole, therefore the pressure is bled off, trying to reduce the unwanted leakage of the killing fluid. This paper presents a hydrodynamic model that takes into account the resistance to flow in the wellbore, inertial forces and fluid losses at the bottomhole. The dynamics of the flow in the annular space is not known in advance and is determined in the process of solving the complete problem. The velocity of fluid movement along the annular pipe, the position of the interface between the media and the losses in the perforation zone are determined by the system of differential equations presented in the paper and are supplemented by closing relations. The process continues until the killing fluid exits the annulus. The final stage of flow stop does not significantly affect the total losses and is therefore omitted, but can be added on a general basis. The calculations provided are performed in the Maple environment. The behavior of the system under various modes of wellhead pressure relief and replacement fluid supply is studied, including the optimal mode that eliminates unwanted losses and is consistent with the kill fluid supply rate. Two modes close to optimal and acceptable for the real technological process are analyzed. The most appropriate is a linear pressure relief from the initial value to the final one, taking into account the excess weight of the kill fluid with the addition of pressure losses due to flow resistance along the wellbore. It is established that taking into account only the change in hydrostatic pressure caused by an increase in the total weight of liquids without taking into account flow resistance gives an incorrect description with large errors.
Source: Oil and Gas Business
Authors: A.V. Tatosov, K.A. Borodina
Language: English
Subfield: Ocean Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: diamond
OpenAlex ID: W4408295771