Stabilized Wellbore Pressure

A South Texas operator was concerned because the previous well ran into abnormal pressures due to gas influx associated with fracture-fed gas. In an attempt to control this gas prior to running and cementing the production liner, excessive mud weights were used and resulted in breaking down the formation. Infield mud weights were anticipated to be 10.0 to 10.5 ppg. Trip pills that were pumped resulted in a system mud weight of 14.0 ppg. Subsequently, large losses of circulation occurred and excessive amounts of NPT were needed to control the well pressure. The operator experienced a wellbore column of fluid compromised by gas influx and therefore tried to maintain the wellbore without knowing the mud weight of the downhole fluid column in well kill operations.

MPD and VIRTUAL HYDRAULICS Modeling

An automated LPAC MPD system was rigged up and wellbore pressures were kept constant using a mud weight of 9.8 ppg. Fluid losses were minimized and wellbore gas influxes were mitigated. Using this method, the fluid column weight was controlled and predictable, and allowed for accurate modeling using VIRTUAL HYDRAULICS. Using MPD, the mud weight was maintained at 9.8 ppg, and kill weight mud pills were constructed to offset the ECD of 12.5 ppg. This equated to a 0.3 ppg trip margin and allowed safe pipe tripping. During the initial casing run, gas influxes were seen and required shut-in procedures. Well control procedures ensued and the casing was stripped to TD. Successful cementing of this liner then proceeded and good returns were seen throughout the cement job.

Days on Well

Days on the well were reduced from 41 days to 17 days with the associated cost saving attributed to successful implementation of @balance Services MPD.