The efficient method for pressure calculation at variable rate

04.10.2021

Our colleagues have published a scientific article «The efficient method for pressure calculation at variable rate» in the «Oil Industry» journal Volume 2021, Issue 09, September 2021. The Siam Well Test software uses algorithm given in this work, so that calculations remain fast with large amounts of data. To get acquainted with the work click at the following link.

The method is proposed to speed up of a bottomhole well flowing pressure calculation with variable rates according to the production history in this paper. The proposed method is based on the use of the pressure drop approximation function, which is a fourth-order polynomial of the logarithm of time. It is shown that the calculated pressure values obtained by the traditional and proposed method (using an approximating polynomial function). The proposed method allows to significantly increase the calculation speed with minimal calculation error.

The results of using the developed method are presented in the table and in the figure below

Model

Calculation time

Maximum relative deviation, %

The mean square deviation of the relative error, %

Direct calculations, ms

Proposed method, ms

Vertical
1972
417
1.47e-7
7.54e-9
Horizontal
557130
471
1.23e-2
2.11e-3
Horizontal multi fractured
1201104
548
1.36e-5
2.38e-6