Perhitungan isi awal gas menggunakan metode volumetrik, metode material balance constant volume no aquifer, dan metode bruns plot pada lapisan "y" lapanan "s"
L apisan “Y†Lapangan “S†yang berlokasi di daerah Pulau Sumatera bagian Selatan dimana formasi lapangan tersebut ialah formasi Baturaja. Pada tugas akhir ini, dilakukan penentuan isi gas awal di tempat OGIP (Original Gas InPlace ) pada Lapisan “Y†Lapangan “Sâ€. OGIP (Original Gas In Place) yang dianalisa pada Lapisan “Y†Lapangan “Sâ€, menggunakan metode Material Balance Constant Volume No Aquifer, dan metode Bruns Plot yang akan dibandingkan dengan perhitungan metode Volumetrik pada Lapisan “Y†Lapangan “Sâ€. Mekanisme pendorong pada Lapisan “Y†Lapangan “S†berdasarkan hasilanalisa didapatkan bahwa reservoir memiliki tenaga pendorong Depletion GasDrive. Berdasarkan hasil perhitungan OGIP (Original Gas In Place) tersebutdidapatkan nilai OGIP dengan metode Volumetrik pada Lapisan “Y†Lapangan“S†didapat sebesar 82,03 BSCF, nilai OGIP dengan metode Material BalanceConstant Volume No Aquifer sebesar 126,804 BSCF, dan metode yang terakhirBruns Plot didapat nilai OGIP sebesar 43,912 BSCF, sehingga dapat disimpulkanhasil OGIP dari metode Bruns Plot ini didapat hasil yang mendekati perhitunganmetode Volumetrik, Dari metode Material Balance Constant Volume No Aquiferdidapat hasil yang optimistik karena tidak memperhitungkan water yang masukkedalam reservoir.
L ayer "Y" Field "S" that is located in the southern part of Sumatra Islandwhere the field formation is the Balfour formation. In this thesis, the content ofthe initial gas in place (Original Gas In Place) at Layer “Y†Field “S†is beingdetermined. Original Gas In Place that being analyzed at Layer "Y" Field "S" is using three methods, they are Volumetric method, Material Balance Constant Volume No Aquifer method and Bruns Plot method at Layer “Y†Field “Sâ€.Drive mechanism at Layer “Y†Field “S†is Depletion Gas Drive, based onanalyzes. Based on the results of Original Gas In Place (OGIP) equation, the value of OGIP with Volumetric method at Layer “Y†Field “S†is 82.03 BSCF, the value of OGIP with Material Balance Constant Volume No Aquifer method is 126.804 BSCF, and from the last method with Bruns Plot, the value of OGIP is 43.912 BSCF. It can be concluded that the OGIP from Bruns Plot is close to Volumetric result. From the Material Balance Constant Volume No Aquifer, the result is optimistic because they do not take into account the water that goes into the reservoir.