English | 2021 | ISBN: 1119760658 | 416 pages | True PDF | 44.84 MB
A popular 1990s formation tester with a single "pumping" probe and one passive "observation port" displaced 180 deg away, designed to measure pressures at two locations for permeability prediction, encounters well known detection problems at low mobilities. This book, using aerodynamics methods, explains why and also reveals the existence of a wide stagnation zone that hides critical formation details. And it does much more. An exact analytical solution is used to validate a new transient, three-dimensional, finite difference model for more general testers, one that guides new hardware designs with independent azimuthally displaced probes having with different rates, flow schedules and nozzle geometries, supports interpretation and formation evaluation, and assists with job planning at the rigsite. The methods also apply to conventional tools, allowing comparisons between older and newer technologies. Importantly, the authors introduce a completely new three-probe design with independently operable active elements that eliminate all older tool deficiencies.