Blowout and Well Control Handbook_04b推荐.pdf

Annular Pressure Profile Previous Page Wait and Weight Method ) i s p ( e r u s s e r P r a l u n n A Volume Pumped (bbls) Figure 4.19 is used, rig personnel would expect that the maximum annulus pressure would be 759 psi, with gas to the surface; that the total pit level increase would be 50 barrels, which might cause the pits to run over; that gas would be at the surface in two hours [(406 — 50)/3] or less, depending on influx migration; and that dry gas might be vented at the surface for a period of 20 minutes, at an equivalent rate of 12 million cubic feet of gas per day. Certainly, these events are enough to challenge the confidence of unsuspect- ing and uninitiated rig personnel and cause a major disaster. Be prepared and prepare all involved for the events to come. CONSTANT CASING PRESSURE, CONSTANT DRILLPIPE PRESSURE, AND MODIFICATION OF THE WAIT AND WEIGHT METHOD After a well kick, the basic philosophy of control is the same, regardless of the procedure used. The total pressure against the kicking formation is maintained at a value sufficient to prevent further fluid entry and below the pressure that would fracture exposed formations. Simplicity is generally emphasized because decisions have to be made quickly when a well kicks, and many people are involved in the control procedure. With the inception of current well control procedures, there was a considerable emphasis on the Drillers Method because the formation influx was immediately displaced. In recent years, it has become apparent that the Drillers Method, while simple, may result in an underground blowout that could have been prevented. Thus, many operators have a