3.10 Closed-in Drill Pipe Pressure. Formation pressure near the wellbore is reduced during flow. When the well is closed in, the borehole pressure will rise until equal to formation pressure. As the drill pipe (and annulus) is in communication, the drill pipe pressure will also rise and stabilize. The drill pipe pressure at this time indicates the amount to increase the drilling fluid density. If the well is not circulated, the gas will slowly rise and increase both wellbore and drill pipe pressures. Drill pipe pressures read after the initial stabilized reading will indicate excessive drilling fluid density increase. To avoid excess wellbore pressures, the choke should be used to bleed drilling fluid from the casing and maintain the initial shut-in drill pipe pressure. These conditions are illustrated in Figure 3.6. To determine the closed-in drill pipe pressure when a back-pressure valve is in the drill string, pressure should be increased slowly using the smallest pump available to determine the pressure at which the back-pressure valve opens. If casing pressure is seen to rise while pumping on the drill pipe, pumping should be stopped and the increase in casing pressure subtracted from drill pipe pressure.
Was this article helpful?
Learn How To Avoid This Horrible Network Marketing Pitfall By Learning From The Mistakes Of Failures And Make Sure It Never Happens To YOU! Most Network Marketers Spend Themselves Into The Poor House Because They Do Not Understand How To Manage Their Cash Flow! Grab An E-book That Will Teach You How To Boost Your Cash Flow For Any Network Marketing Business!