Well testing is the systematic measurement of flow rates, pressures, and fluid properties from an individual well under controlled conditions. It serves as the foundation for production allocation, reservoir engineering analysis, and regulatory reporting. In the United States, state regulatory agencies such as the Texas Railroad Commission and the Oklahoma Corporation Commission require periodic well tests — typically monthly or quarterly — to maintain accurate production records and ensure proper allocation of commingled volumes.
How It Works
Well tests vary in complexity and purpose, ranging from simple rate measurements to multi-day pressure transient analyses:
- Initial Potential Test (IP) — Conducted shortly after well completion to establish the maximum sustained flow rate. The IP rate is a key metric for evaluating completion effectiveness and comparing well performance across a development program. A strong Permian Basin horizontal well may IP at 1,000 to 3,000 BOEPD.
- Production (Rate) Test — A periodic measurement of oil, gas, and water rates through a test separator. The well is routed to a dedicated test separator for 12 to 24 hours, and rates are measured using orifice meters, Coriolis meters, or calibrated tanks. Results establish allocation factors for the next period.
- Buildup Test — The well is shut in and bottomhole pressure is recorded as it recovers toward static reservoir pressure. Analysis using Horner, MDH, or type-curve methods yields permeability, skin factor, and average reservoir pressure — critical inputs for reservoir simulation.
- Drawdown Test — The well is opened at a constant rate and flowing bottomhole pressure is recorded over time. Provides similar reservoir parameters to a buildup test but requires rate control.
- Multi-Rate Test — The well is produced at several stabilized rates, and corresponding flowing pressures are recorded. Used to construct the Inflow Performance Relationship (IPR) curve, which defines the well's deliverability envelope.
Key measurements captured during testing include oil rate (BOPD), gas rate (Mscf/d), water rate (BWPD), gas-oil ratio (GOR), flowing tubing pressure (FTP), flowing casing pressure (FCP), and fluid samples for BSW and API gravity.
Why It Matters
Accurate well tests are the basis for production allocation, revenue distribution, and reserve estimation. A 5% error in a well test on a lease producing 1,000 BOPD at $70/bbl translates to $127,750 per year in misallocated revenue. Regulatory agencies impose penalties for missing or inaccurate test data. Beyond compliance, well tests provide the data that production engineers need to evaluate artificial lift performance, diagnose wellbore problems, and optimize completion designs for future wells.
How Netora Handles Well Testing
Netora E&P Production manages the complete well test workflow — scheduling tests, recording results by phase (oil, gas, water), calculating allocation factors, and flagging wells that are overdue for testing. Test results automatically feed into the production allocation engine, ensuring that reported volumes match measured performance. Historical test data is stored for decline curve analysis and reservoir engineering studies. Learn more about Netora E&P Production.