Enhancing a Low Enthalpy Well for Production: The Tongonan Experience

Abstract

The paper presents a recent experience in Tongonan, Leyte in the application of production technology to enhance a low enthalpy well for production. The procedure was applied to a deep well drilled at the outflow of the Upper Mahiao sector in the Leyte Geothermal Production Field. Deep well drilling is one of the resource management strategies implemented in Tongonan, Leyte to sustain steam requirement to power plants. This approach aims to produce from the deeper, liquid region of the reservoir, in order to better distribute extraction between the shallow two-phase region and deep resource allowing liquid recharge to Tongonan reservoir. However, commercial production of the new well was a challenge during its discharge testing. Evaluation of the discharge data showed that the well is mainly producing fluids with low enthalpy which hinders it from attaining the target high commercial well head pressure (WHP), unlike the neighboring wells producing from the two-phase region. Thus casing perforation and acid injection were conducted to avail of the hotter zone behind the cased-off part and to initiate some contribution from the two-phase region leading to its successful production and commissioning to the system.