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

  • 26 November 2014

    US EIA: Increase in energy demand requires 33 million bbl/day more oil

    The world is going to need one-third more oil between 2010 and 2040, with developing countries, such as China and India, accounting for a major portion in the increase in...

  • 25 November 2014

    Prescriptive Analytics prescribes how to complete wells to maximize production

    "Big data" is taking on a new role in industry, where companies are combining the findings from geology and geophysics with new data collected from advanced technologies...

  • 25 November 2014

    Petrobras completes drilling first appraisal well in Libra Consortium

    Petrobras recently completed drilling the first appraisal well in the Libra area, the 3-BRSA-1255 (3-RJS-731), known as NW1. Located in the Northwest portion of the Libra block, in the pre-salt layer of the...

  • 24 November 2014

    Ensign secures contracts for 2 ADR 1500S pad drill rigs in Montney area

    Ensign Energy Services has signed contracts for two of its new ADR 1500S pad drill rigs for a major operator in the Montney area of northeast British Columbia...

  • 21 November 2014

    Statoil cancels Stena Carron rig contract offshore Angola

    Statoil has decided to cancel the Stena Carron rig contract after fulfilling the work commitments in the Statoil-operated blocks 38 and 39 in the Kwanza basin offshore Angola...

  • Read more news