PTA and Well Performance Assessment of Dry and Liquid Rich Gas in Unconventional Tight Sands: A Middle East Case Study

Abstract

Saudi Aramco is actively appraising the numerous unconventional shale and tight sand opportunities located across the kingdom of Saudi Arabia. The early phase of the unconventional gas program in the company has been directed towards exploration data gathering activities through drilling, coring, open-hole logging and completion of shale and tight sand gas resources. Due to the ultra-tight nature of these reservoirs, several vertical and horizontal wells have been drilled and completed with multistage hydraulic fractures to be able to produce them. Initial flow back tests, in addition to long term pressure build-up, have already been conducted on some of these wells, the analysis of which will help to characterize and better understand these tight hydrocarbon reservoirs. This paper discusses the results of pressure transient analyses and modelling performance of two unconventional tight sand wells. An Integrated workflow was developed for reservoir characterization and fluid flow modeling using well test analyses and a simulation tool designed specifically for unconventional reservoirs. Post fracture flowback data along with available petrophysical interpretation, geological and geophysical analyses and 3-D hydraulic fracture models were used to build and calibrate single well numerical models. For the purpose of comparison, two wells were selected: one from a dry gas reservoir, while the other was from a rich gas-condensate reservoir.