Gas influx into a wellbore, called A "kick", is detected by two different, yet complementary methods during active drilling of the borehole. The first method is based upon the existence of standing wave patterns generated by pressure oscillations of the drilling rig mud pumps. Such standing wave patterns form time sequences of maximum and minima as a gas slug moves upwardly in the annulus. The time between such peaks of such oscillations is measured and forms the basis for generation of one first kick signal. A continuous increase in the phase between annulus and drill string standing waves forms the basis for another standing wave kick signal. The second method uses acoustic signals from a downhole source near the bottom of the borehole which are transmitted at different speeds in the annulus mud and in the interior drill string mud, where the annulus mud may be gas cut. A difference in arrival time between the signals is determined, and if large enough, causes a second kick signal to be generated. A third method may be used where at least two drilling pumps are used in the drilling system. Such method determines the total travel time, from standpipe to drill string and up the annulus, of a beat frequency pressure wave caused by slightly different frequencies of the two pumps. An alarm signal is generated if the total travel time is greater than a computed threshold.
Methods and systems are provided for maintaining fluid pressure control of a well bore 30 drilled through a subterranean formation using a drilling rig 25 and a drill string 50, whereby a kick may be circulated out of the well bore and/or a kill fluid may be circulated into the well bore, at a kill rate that may be varied. A programmable controller 100 may be included to control execution of a circulation/kill procedure whereby a mud pump 90 and/or a well bore choke 70 may be regulated by the controller. One or more sensors may be interconnected with the controller to sense well bore pressure conditions and/or pumping conditions. Statistical process control techniques may also be employed to enhance process control by the controller. The controller 100 may further execute routine determinations of circulating kill pressures at selected kill rates. The controller may control components utilized in the circulation/kill procedure so as to maintain a substantially constant bottom hole pressure on the formation while executing the circulation/kill procedure.
The present invention provides a method of monitoring a well to detect and provide warning of pipe sticking. The method includes 1) monitoring the downhole annular fluid pressure of a drilling fluid being pumped through the drill string during drilling over predetermined intervals of time to obtain a series of pressure measurements, 2) monitoring the torque required to rotate the drill string during said periods to obtain a series of torque measurements, and 3) comparing the series of downhole annular fluid pressure measurements with the series of torque measurements so as to identify corresponding changes in both, and 4) raising an alarm when the magnitude of the changes passes predetermined alarm values.
A system and a method for prediction and treatment of all kinds of slugs being formed in a flow line system or wellbore tubing transporting a multiphase fluid towards a downstream process including a separator or a slug catcher at the process inlet. The system includes a slug detector (1) located downstream of the point for slug initiation and upstream of the process and a computer unit (4) integrating the flow line system and the downstream process including software which determines the type of the slug, its volume and predicts its arrival time into the downstream process. The computer unit processes all its incoming data to obtain an optimum regulation of the process so that process perturbations due to incoming slugs are reduced to a minimum through the process.
A system inserted between the base of a riser (5) and a production well flowline for collecting an effluent consisting of at least a gas phase and a liquid phase, includes a capacity (1) including an inlet port for the effluent and two outlet ports, one in the upper part of said capacity for the gas phase, the other in the lower part for the liquid phase communicating with the base of the riser, a gas supply line (2) connecting the gas outlet port to the riser at a predetermined height H, including a flow control valve (3), and an instrumentation set for locating the level of the liquid/gas interface in the capacity, a computer receiving the instrumentation data for determining the instructions for controlling said flow control valve so as to adjust the volume of gas fed at height H into the riser.
