Abstract

Many oil and natural gas producing wells suffer from a phenomenon know as 'water coning' wherein a water saturated formation underlies the hydrocarbon bearing formation without any impermeable barriers separating the water and hydrocarbon. In the process of withdrawing hydrocarbons from the formation, the underlying water is drawn by viscous forces into the hydrocarbon bearing section when conventional completion techniques are applied. In-Situ Gravity Segregation (IGS) is an alternative completion technique that mitigates the effects of water coning. This method entails producing a significant volume of water through perforations in the well casing (water sink) below the OWC surface concurrently with producing hydrocarbons through perforations in the well casing (hydrocarbon sink) above the OWC surface. Producing water below the OWC tends to suppress the creation of the water cone, thereby protecting the hydrocarbon section from water invasion. Essentially, the downward viscous forces imposed by withdrawing water from beneath the OWC balance the upward viscous forces imposed by withdrawing hydrocarbons from above the OWC. By using this technique, the hydrocarbon rates can be improved greatly over conventional critical oil rates associated with water coning.

The IGS completion technique is new technology intended to reduce coning effects and has mainly been focused towards implementation on new completions with no prior history of coning. This paper focuses on the application of IGS completion technology for a well located in Petapahan Field, Sumatra, Indonesia with over 5 years of prior water coning. A field trial was designed in an attempt to mitigate existing water coning problems. A new pumping system was designed to handle to two independent fluid streams. Design, implementation, and field results will be presented along with performance predictions from reservoir simulations.