# Drill Pipe Choke Manifold

Ph = 5200 psi (in annulus) PUMP AT KILL RATE HOLDING CONSTANT CHOKE MANIFOLD PRESSURE CHANGE IN BHP = 200 psi increase

SECTION 1 : FUNDAMENTAL PRINCIPLES OF WELL CONTROL

Figure 1.23

To eliminate this problem, two methods exist. First, by reducing choke manifold pressure by an amount equal to a known CLFL (adjusting choke manifold pressure to SICP -CLFL), the effect of the CLFL is negated. This is accomplished by reducing the original SICP by the amount of CLFL while bringing the pumps to speed (see Figure 1.23). Once kill rate pressure has been established, the choke operator switches over to the drill pipe gauge and follows the drill pipe pressure graph in the usual way.

Or secondly, given a choke manifold configuration with separate pressure gauges for choke and kill lines, it is possible to utilise the kill line (shut off down-stream of the gauge outlet to prevent flow, thus eliminating friction) as a pressure connection to a point upstream of any potential CLFL (known or unknown). This is shown in Figure 1.24. If the kill line gauge in this instance is kept constant while bringing the pump to speed, the effect of CLFL is eliminated.

### Note the advantages of the second method:

1. The gauge reading choke manifold pressure will show a decrease after pump is up to speed. The amount of this decrease is equal to the CLFL.
2. No precalculated or pre-measured CLFL information is required.
3. The kill line gauge can be subsequently used like the choke manifold pressure gauge on a surface stack for the purposes of altering pump rates or problem analysis.

NOTE: If the second method of handling the

CLFL situation is preferred, it would be advisable to rig a remote kill line pressure gauge which could be seen by the choke operator.

1000 PSI

KLFL 0 PSI (STATIC)

CHOKE MANIFOLD

CLFL 200 PSI (DYNAMIC)

Figure 1.23

CHOKE MANIFOLD

DRILL PIPE

CLFL 200 PSI (DYNAMIC)