Pressure Transient Analysis in Injection Wells

• Main Author: Ali Asfak Hussain, Hasnain
• Format: Thesis
• Language: English
• Published: 2012
• Online Access: http://utpedia.utp.edu.my/3464/1/Final_Hard_Bound_Copy_report_.pdf; http://utpedia.utp.edu.my/3464/

A composite reservoir model is used to analyze well tests from a variety of secondary and tertiary recovery projects. Water flooding is widely used as a secondary recovery technique. Due to injection, a water bank and oil bank regions would be formed. Each region has its own rock and fluid properties. and the main scope of well test study during injection would give a clear idea of the displacement process of oil by water and to study the variation in fluid parameters in the reservoir. Pressure transient analysis of a two-region composite reservoir is considered extensively in the literature. An infinite reservoir with injection well placed at the centre of the reservoir is used to inject water at a constant rate, this gives rise to the applicability of line source solution. 1 dimensional radial homogeneous model is developed using ECLIPSE 100. Injection and falloff analyses are made on this injection well, by initially assuming zero wellbore storage effects and zero skin. Initial studies from the pressure transient analysis showed the effects of the two banks formed. Injection and falloff studies were carried out for the initial case first. The pressure vs. time data generated from the numerical simulation model ECLIPSE 100 for injection and falloff tests were further studied and their properties like skin, permeability and mobility were evaluated and compared with the input data. Saturation profile showed the movement of the two bank system, whereas, the total mobility profile showed variation in saturation gradient and the changes in total mobility away from the wellbore. Further studies were made by changing few input parameters and studying pressure behavior for both injection and falloff tests. Parameters studied were, effect of changing oil viscosity, relative permeability, wellbore storage, and skin. The changes in mobility ratio by changing oil viscosity showed different pressure behavior for each case, variation in the pressure curves were clearly visible after the flood out zone was reached. Multi-bank analysis method was found to be applicable for different sets of relative permeabilities. The effect of skin factor was only observed V when pressure difference was plotted against time, and showed no effect on the semi-log plot, derivative plot and the mobility profile. Presence of wellbore storage on pressure curves was dominant during the early time region and the elimination of wellbore storage effects is very important for accurate interpretations of the early time region.