Sin Phu Horm (SPH) gas field locates in the province between city of Udon Thani and Khon Kaen, North-Eastern of Thailand. Phu Horm structure is located in Blocks EU1 and E5N in the northeastern of Thai and. It is 45 km and 75 km north of EMEPKI Nam Phong Gas Field and Khon Kaen city. PTIEP became a partner with 20% interest in Block ESN in 1990. The block covers an area of 39.31 sq. km of the Phu Horm South Structure. In 2005 PTIEPS acquired 20% interest in Block EU1, which has an area of 192.61 sq. km. and covers the Phu Horm North Structure. Then PTIEP acquired HESS's interest and along with an operatorship on 23 April 2014, therefore PTIEP's interest increased from 20% to 55%. Partners of the field are APICO LLC and ESSO with 35 % and 10 % interest respectively.