Abstract
Natural gas has been widely touted as a transition fuel due to its lower greenhouse gas emissions when compared to other fossil fuels such as coal and oil, serving as a bridge fuel between the fossil fuels and the renewables. This has made gas condensate reservoirs (GCRs) a crucial resource in meeting the increasing demand for cleaner, more affordable energy for the energy transition.
GCRs while producing gas also deliver valuable condensate liquid that could pose production challenges. An example is condensate banking around the wellbore which reduces overall well productivity. Furthermore, GCRs also require more rigorous pressure-volume-temperature (PVT) modeling to cover the producing lifecycle of the reservoir and understand how much of the condensate will be produced to the surface.
Resolving these additional complexities with GCRs requires proper surveillance data acquisition, PVT analysis, reservoir simulation to improve reservoir understanding and integrated asset models to bring all the knowledge together and capture flow interactions. Data such as fluid lab tests, reservoir pressure trend, pressure transient testing and production tests are analyzed; giving insights into fluid, reservoir, and near-wellbore properties. Gas wells are typically online for extended periods to meet daily contract quantities (DCQ). This poses a challenge to the acceptable duration of pressure build-up (PBU) tests. For this, a review of some opportunistic extended build-up tests that were done during a scheduled Turn-Around Maintenance that allowed a deeper radius of investigation into the reservoirs is presented.
This text builds on existing literature on the management of gas condensate reservoirs highlighting lessons learnt and best practices while using case studies from some Niger Delta reservoirs. The case studies presented cover a wide range of some reservoir parameters that impact expected ultimate recovery such as permeability and condensate-gas-ratio (CGR) while discussing field practices and results.
