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Case Study: Confidence in Measurement Accuracy Saves Operator More Than USD 1.8 Million

StethoScope formation pressure-while-drilling measurements reduce risk and cut 55 h of rig time on longest multilateral in India

Challenge: Measure pressure and mobility profile in long horizontal multilateral well with minimal rig time and risk.

Solution: Use StethoScope formation pressure-while-drilling (FPWD) service in combination with LWD tools to quantify depletion of reservoir.

Result:

  • Quantified depletion, identified high-mobility layers, and delineated oil zones below gas/oil contact.
  • Saved 55 h of rig time and more than USD 1.8 million by eliminating need for postdrilling logging runs.

Minimize risk and rig time

An operator needed to quantify depletion in a brownfield in a thin oil rim reservoir. This required measuring pressure and the mobility profile in what was to be the longest horizontal multilateral well ever drilled in India’s Krishna-Godavari basin—and to do so with a minimum of risk and rig time. This would enable the operator to record a permeability profile along the laterals in order to optimize the completion design, to assist in making a decision on installation of an inflow control device, and to determine fluid gradients.

Measure pressure while drilling

The operator successfully drilled the well to a measured depth of 6,256 m and a TVD of 3,289.7 m with an openhole sidetrack. Use of the StethoScope FPWD service in combination with one LWD service provided the needed measurements in the 12 1/4-in landing section and two 8 1/2-in lateral sections, while minimizing risk and rig time. Pressure gradients in the 12 1/4-in section indicated oil in two zones and showed that the zones were not in hydraulic communication with one another. StethoScope service achieved an excellent average seal success rate of 86.5% in the landing section and the two laterals.

Trust the accuracy of FPWD measurements

StethoScope pressure measurements made at 30 stations enabled the operator to quantify depletion in the laterals and correlate it to layer permeability, identify high-mobility layers, and provide pressure gradients to help delineate oil zones below the gas/oil contact. The operator had confidence in the data produced by the StethoScope service and did not pursue additional measurements, thereby saving an estimated 55 h of rig time and more than USD 1.8 million.


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