Pairing Wireline Formation Testing With Drillstem Testing Unlocks Potential

_ This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 224937, “Synergy of Intelligent Wireline Formation-Testing Platform Together With Drillstem Testing To Unlock Hydrocarbon Potential in Asia Greenfield,” by Dennis Ling, SPE, Saifon Daungkaew, SPE, and Morten Kristensen, SPE, SLB, et al. The paper has not been peer-reviewed. _ In Southeast Asia, reservoirs are frequently laminated, thinly bedded, and compartmentalized. Testing every individual (main) zone with drillstem tests (DSTs) is not economical because of cost and rig-time constraints. Interval pressure transient tests (IPTT) and deep transient testing (DTT) have been introduced as greener alternative wireline-testing methods. This paper provides examples wherein DSTs with either IPTT or DTT have been acquired on the same well. Digital Workflow for DTT First, a power planner is run to determine the maximum system power available. Next, expected reservoir properties are used to design an initial downhole toolstring. Fluid-cleanup simulation is performed for different inlet types, with sensitivity analyses for pumpout time and rate and rock and fluid properties. In parallel, pressure transients are simulated using analytical solutions for selected flow and buildup sequences to ensure that an appropriate signal/noise ratio will be observed and any radius-of-investigation (ROI) objectives can be met. Next, wellbore dynamic simulations are run to predict the interaction between the pumped hydrocarbon and the selected mud system. The overbalance must always meet the operator’s minimum requirements during operation, and both hydrocarbon influx and circulating operating windows must be defined. During this early design phase, several iterations may be required to ensure that selected hardware and flow sequences are well-paired with the cleanup and pressure-transient requirements. When logging operations begin, the continuous permeability profile derived from high-resolution nuclear magnetic resonance (NMR) is integrated with other logs and the quick-look interpretations are used to update cleanup and pressure-transient simulations. As IPTT data become available, they are used to calibrate this derived continuous permeability. Downhole wellbore pressure and rate measurements are sent to the platform, where they are compared with wellbore-dynamics simulations. If deviations from the planned flow and buildup sequences exist, cloud-based platform architecture enables quick simulation updates to ensure that measured and predicted data are always up to date. Downhole-fluid-analysis technologies allow properties to be viewed vs. depth and placed in context with 2D reservoir logs and 3D reservoir structure.