Abstract

A large area of the offshore Gulf of Thailand has remained unexplored due a territorial dispute between Thailand and Cambodia that goes back over sixty years and still remains unresolved. The Thai Cambodia Overlapping Claim Area covers an area of over 27,000 square kilometres and is the last of the disputed zones to be resolved between ASEAN members in the Gulf of Thailand. Recently new efforts are being made to reach agreement.

Limited and poor quality seismic data shot over the area before 1975 indicates the presence of two deep north-south Tertiary grabens, the Eastern Pattani Trough and the Khmer Trough which are developed in response to the dextral sheer movement on a series of deep crustal faults. Although there is no well control in the OCA, structural development in Tertiary fluvial and deltaic sequences similar to known productive trends in Thai waters has suggested that the area will contain reserves of gas, condensate and oil.

Exploration activity in tightly held licences on the Thai side of the OCA has confirmed the presence of commercial quantities of liquid and gaseous hydrocarbons close to the boundary, from the Jasmine Field in Block B5/27 in the north to the Gomin Field in Block B13 and Ubon Field in Block B12/27 in the south.

By comparison, since the early 1990's exploration in the offshore area of Cambodia has been slow and, while oil and gas has been encountered, a commercial flow rate has not yet been achieved nor commercial reserves identified. A large new licence covering most of the prospective offshore area was awarded last year by the Cambodia National Petroleum Authority to Chevron and MOECO, and a drilling campaign is underway for 2003.

With both countries currently net importers of oil and with Thailand facing the prospect of importing up to 50% of its gas from its neighbours within 10 years, there is a large impetus to find new hydrocarbon reserves that are even partially owned by Thailand.

On the other hand, revenues from hydrocarbon sales to their neighbours will greatly stimulate the growth of Cambodia's fragile economy in the near term. In the longer term, any commercial hydrocarbon development will contribute to the supply of Cambodia's domestic energy needs, freeing valuable hard currency for further national development. The desire on behalf of the Thai and Cambodian governments to come to an equitable agreement over the OCA is therefore strong; as is the enthusiasm of the licence holders on both sides to start exploration and thus 'open the vault' that has been locked for almost 30 years.

Presented at: 2005 South East Asia Petroleum Exploration Society (SEAPEX) Conference, Singapore, 2003