Derivation and application of mathematical model for well test analysis with variable skin factor in hydrocarbon reservoirs

Abstract

ARTICLES YOU MAY BE INTERESTED INModeling and simulation of the zinc-nickel single flow batteries based on MATLAB/ Simulink AIP Advances 6, 125302 (2016) Skin factor is often regarded as a constant in most of the mathematical model for well test analysis in oilfields, but this is only a kind of simplified treatment with the actual skin factor changeable. This paper defined the average permeability of a damaged area as a function of time by using the definition of skin factor. Therefore a relationship between a variable skin factor and time was established. The variable skin factor derived was introduced into existing traditional models rather than using a constant skin factor, then, this newly derived mathematical model for well test analysis considering variable skin factor was solved by Laplace transform. The dimensionless wellbore pressure and its derivative changed with dimensionless time were plotted with double logarithm and these plots can be used for type curve fitting. The effects of all the parameters in the expression of variable skin factor were analyzed based on the dimensionless wellbore pressure and its derivative. Finally, actual well testing data were used to fit the type curves developed which validates the applicability of the mathematical model from Sheng-2 Block, Shengli Oilfield, China. C 2016 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).

A mathematical model and semi-analytical solution for transient pressure of vertical fracture with varying conductivity in three crossflow rectangular layers

“…A single-phase fluid flows from the three-layered sealed rectangular reservoir to a vertical fracture with constant conductivity at a constant flow rate Q , as presented by equations (1)–(8) (Liu et al., 2016; Wang et al., 2005) …”

“…C FD can be defined as the ratio of the ability of the fracture to carry fluids into the well to that of the formation to carry fluids into the fracture (Gringarten et al, 1974(Gringarten et al, , 1975Liu et al, 2016;Prats et al, 1962).…”

“…When hydraulic fracturing is conducted in a multilayered formation, the vertical hydraulic fracture can be divided into the three categories of uniform-flux, infinite-conductivity, and finite-conductivity fractures based on the dimensionless fracture conductivity ( C FD ). C FD can be defined as the ratio of the ability of the fracture to carry fluids into the well to that of the formation to carry fluids into the fracture (Gringarten et al., 1974, 1975; Liu et al., 2016; Prats et al., 1962).…”

Modeling and analyzing gas supply characteristics and development mode in sweet spots of Sulige tight gas reservoir, Ordos Basin, China

“…In actual production, radial flow is generally presented in the vicinity of the bottom of each well. Thus, the mathematical model can be written in the coordinate system (Liu et al., 2016; Stehfest, 1970).…”

Combining experimental and logging data for calculation of the true skin factor of a horizontal well

“…The apparent skin factor is estimated using polymer rheological properties, grid size, wellbore radius, etc and can apply to any polymer rheology. Using the definition of skin factor, Liu et al 14 defined the average permeability of a damaged area as a function of time to establish a relationship between variable skin factor and time. The variable skin factor derived was then introduced into existing traditional models, rather than using a constant skin factor, and this newly derived mathematical model for well test analysis considering variable skin factor was solved by Laplace transformation.…”