Field X is a large greenfield high-pressure/high-temperature (HP/HT) carbonate development offshore Malaysia. The current development plan requires each of the wellhead platforms (WHPs) to host multiple high-rate gas wells. When closely spaced wells produce simultaneously, they can perturb the local geothermal temperature profile and can affect the thermal response of individual wells, the platform pile and conductor strengths, and infill well designs. The complete paper outlines a technique to evaluate formation temperature shifts when closely spaced wells are produced concurrently and apply that to validate the design basis for new development.
Field Overview
Field X features reservoir pressure of greater than 10,000 psi and temperatures near 200°C. The reservoir also contains high levels of sour contaminants (CO2 and hydrogen sulfide).
The current development plan requires multiple wells producing simultaneously at a high gas rate from a single WHP. Flowing wellhead temperature (FWHT) can reach 170°C under these flowing conditions.
The typical well in the subject field accesses a gas-bearing reservoir where the maximum bottomhole temperature is nearly 200°C. Each producer well is designed to produce gas with a high rate of 200 MMscf/D with expected FWHT of up to 170°C. The development team investigated the following effects of thermal interference:
- Higher FWHT
- Higher string temperatures during production
- Increased wellhead growth and reduction of soil shear strength and pullout capacity of structural casings that support the well
- Effect on infill drilling in the perturbed thermal zone
The analysis conducted during this study estimated the following parameters for the design:
- Location of the thermal front of a given well in the formation as a function of time
- Time required for thermal fronts of neighboring wells to meet
- Perturbation of the undisturbed temperature in the interference zone
- Effect of perturbation on the producing wellbores
The complete paper includes a discussion of multiwell thermal interaction.
Heat Transfer From a Wellbore
In a producing wellbore, energy is exchanged between the wellbore and the formation.
