CATEGORIZED | News

MPD reduces NPT in Tizon Field's fractured carbonates

Posted on 17 February 2009

The biggest challenge was the differential pressure between the JST (tight gas formation) and JSK (naturally fractured carbonate) formations. In addition, an overbalanced condition was desired once inside the JSK formation due to the risk of H2S and to minimize the possibility of a gas influx from the JST formation.

High bottomhole temperature was another risk as it could modify mud rheology and fluid specific volume. Especially on deeper wells with a narrow mud weight window and high temperatures, the team knew that the difference between theoretical and actual values of drilling fluid properties couldn’t be ignored.

The actual well casing configuration and cement tops were used for modeling, with a surface temperature of 34°C and a bottomhole temperature of 181°C at 6,000 m (TVD) assumed. The temperature profile was then calculated for a near-balance condition at total depth.

For this project, MPD was used to allow the operator to dynamically manage the influxes coming from JST, thus reducing pressure-related events NPT. Improved well control was also anticipated with MPD because it provided flexibility to manipulate annular pressure.

The 6 ½-in. section was spudded with a 1.50 SG mud and gradually decreased to 1.46 SG as drilling depth approached the JSK formation. A wellhead pressure of 80 psi was kept while drilling or circulating. During connections, to compensate for the pressure provided by annular friction losses, the wellhead pressure was raised to match the circulating bottomhole pressure.

Trip gas was a constant factor while drilling the well due to the high bottomhole temperature. The use of MPD equipment allowed operations to continue during influx events, which saved the rig up to 30 hours in well control procedures.

The well was drilled down to 6,424 m with a 1.50 SG drilling mud. Only one trip was performed before reaching TD.

Overall, the team noted that one of the most remarkable benefits from using MPD in this project was the minimizing of NPT while drilling related to formation influxes during connections and tripping. Also, no differential sticking or losses were experienced in the transition zone from JST to JSK.

Details from this case study can be found in IADC/SPE 122200, “Successful Application of MPD Technique in a HP/HT Well Focused on Performance Drilling in Southern Mexico Deep Fractured Carbonate Reservoirs.”

Leave a Reply

*

FEATURED MICROSITES


Recent Drilling News

  • 17 April 2014

    Shell makes deepwater gas discovery offshore Malaysia

    Shell has made an exploration discovery offshore Malaysia in the Rosmari-1 well located 135 km offshore Malaysia in Block SK318. The well was drilled to a total depth of 2,123...

  • 16 April 2014

    Maersk Drilling takes delivery of ultra-deepwater drillship

    Maersk Drilling has taken the delivery of its second drillship, Maersk Valiant from the Samsung Heavy Industries (SHI) shipyard in Geoje-Si, South-Korea. Maersk Valiant has begun its voyage toward the...

  • 16 April 2014

    Ensco orders new jackups from Lamprell

    Ensco has ordered two high-specification jackups, ENSCO 140 and ENSCO 141, for delivery in mid-2016 from Lamprell’s shipyard in the United Arab Emirates. The rigs will also...

  • 16 April 2014

    MPD/UBD successfully drills sidetrack after 6 failed conventional drilling attempts

    In the Brookeland Field in East Texas, conventional drilling methods failed in six attempts to drill a “straightforward” horizontal wellbore. The original well had surface casing installed...

  • 16 April 2014

    Chevron’s DGD training program serves array of learners across generations

    Since 2008, more than 400 people – from operators, drilling contractors, service companies and regulators – have completed Chevron’s dual-gradient drilling (DGD) training...

  • Read more news