Methods for evaluating inflow and outflow in a subterranean wellbore

摘要

A method for evaluating inflow or outflow in a subterranean wellbore includes acquiring first and second axially spaced pressure measurements in the wellbore. The pressure measurements may then be processed to obtain an interval density of drilling fluid between the measurement locations. A tool string including a large number of axially spaced pressure sensors (e.g., four or more or even six or more) electronically coupled with a surface processor via wired drill pipe may be used to obtain a plurality of interval densities corresponding to various wellbore intervals. The interval density may be measured during static conditions or while drilling and may be further processed to compute a density of an inflow constituent in the annulus. Changes in the computed interval density with time may be used as an indicator of either an inflow event or an outflow event.

主权项

1. A method for computing a density of an inflow constituent in a subterranean wellbore, the method comprising:
(a) rotating a drill bit in a subterranean wellbore, the drill bit being deployed in a drill string including first and second axially spaced along string pressure sensors, said rotating operative to drill the wellbore and produce formation cuttings which are transported to a surface location via drilling fluid in a wellbore annulus; (b) using the first and second spaced along string pressure sensors to make first and second subsurface annular pressure measurements at corresponding first and second measured depths in the wellbore; (c) transmitting the first and second pressure measurements to a processor; (d) causing the processor to process the first and second annular pressure measurements to compute an annular interval density between the first and second measured depths in the wellbore; and (e) causing the processor to process the annular interval density, a volume fraction of drilling fluid in the annular region, a density of the drilling fluid in an annular region of the wellbore, a volume fraction of the cuttings in the annular region, a density of the cuttings in the annular region, and a differential flow rate to compute the density of the inflow constituent.