Drill stem and Deliverability test analysis: Case study of a gas field well test analysis in Myanmar

Drill-stem tests are performed to confirm or prove the presence and the producibility of oil and gas that is detected by the other services. It is usually performed on exploration wells are often the key to determining whether a well has found a commercial hydrocarbon reservoir. Reservoir parameters specifically related to productive capacity such as pressure, permeability can be determined through drill stem test. Common sequence of a drill stem test includes of a short flow period mostly five or ten minutes, which is followed by a buildup period of about an hour that is used to determine initial reservoir pressure. Afterwards, the well is allowed to flow for next four to twenty four hours to establish stable flow to the surface then the well is shut in again for final shut in or build up test which is used to determine permeability thickness and flow potential.
Drill stem tests are usually combined with deliverability tests which is referred to the testing of a well to measure its production capabilities and flow performance relationships. Most common deliverability tests are flow after flow, single-point, isochronal and modified isochronal tests. Two main applications of deliverability tests are obtaining the absolute open flow (AOF) potential and generating reservoir inflow performance relationship (IPR) or gas backpressure curve.
This paper discusses the case study of drill stem test and deliverability test done on a well in one of the gas fields located in Myanmar. Topics will cover the analyses of reservoir parameters through initial build up test, final build up test during the drill stem test and analysis of flow after flow test for Darcy and Non Darcy skin factors. In addition, it will further discusses the comparison of deliverability tests (empirical and analytical) and lastly perform production forecasting. The analyses are performed through Pansystem which is the well test analysis software developed by Weatherford Inc.