The Exploration and Development of the Songkhla D and E fields

The, Ronald; Pringle, John; Peace, Geoff; Laird, Andrew; Maykho, Sirinya; Kudisri, Rapee; Veerachai, Tony
Coastal Energy, Bangkok, Thailand.

Since early 2008, the Songkhla and Bua Ban oilfields have been producing from Lower Oligocene and Eocene reservoir in the Songkhla Basin. In April 2011, Coastal Energy made a significant Miocene oil discovery at the Songkhla E location during their exploration drilling campaign. Subsequently, Coastal Energy drilled a further 7 appraisal / development wells at the Songkhla E location. After the rig moved off, a Mobile Offshore Production Unit (MOPU) positioned over the wellheads. A Hydraulic Workover Unit (HWU) moved in and completed 7 producers with down hole pumps and one injector. These wells were then connected to a spread moored tanker and first oil was produced three months after the Songkhla E discovery. The Miocene play indicated possible connection to the Songkhla D location. A similar approach of drilling was used to appraise the Songkhla D area. With drilling crestal and long reach wells, Coastal Energy has proven the Miocene oil reservoir covers the D and E area. Songkhla D oil production commenced in December 2011 using a second MOPU.

The Songkhla D and E wells discovered the first Miocene oil producing reservoirs in the Songkhla basin. The discovery significantly increased Coastal's reserve base and doubled the company's production. The productive Miocene sands in the Songkhla Basin are likely of fluvial origin. They are interpreted as stacked channels with a blocky GR character and fining upward trends near the top. Core description and detailed core analysis is ongoing. The oil is mainly trapped by three way structural dip closures against normal faults. The Miocene oil is viscous (around 9cP) with a low GOR (5 scf/stb) and has a gravity around 28 API. Preliminary studies indicate the oil was generated from a lacustrine shale source rock. Due to the oil properties and structural setting, a key development strategy is to drill horizontal wells away from the oil water contact. The seismic resolution at reservoir level is sufficient to support the well placement process, although initial seismic studies have indicated that sand prediction and inversion are of limited value.

The Songkhla project demonstrates that oil fields can be put on stream quickly with a minimum of capital exposure dramatically improving the project economics. For Coastal Energy, this concept has proven that with multiple exploration prospects in a drilling campaign, risk mitigation is taken into account.

AAPG Search and Discovery Article #90155©2012 AAPG International Conference & Exhibition, Singapore, 16-19 September 2012