Integrasi Seismik Inversi Akustik Impedance (Ai) Dan Elastic Impedance (Ei) Untuk Karakterisasi Reservoir, Studi Kasus: Lapangan Muon

Penelitian ini memaparkan aplikasi metoda inversi Acoustic Impedance (AI) dan Elastic Impedance (EI) pada data seismik 3D di lapangan Muon , formasi Air Benakat sub-basin Jambi. Data sumur yang digunakan sebanyak dua belas sumur yang terdiri dari enam sumur vertikal dan enam sumur miring. Inversi AI dilakukan untuk mengetahui persebaran lapisan poros. Inversi EI yang memasukan komponen Vs dan sudut digunakan mendeteksi keberadaan hidrokarbon. Inversi AI dan EI dilakukan dengan metode Model Based Hard Constrain. Hasil crossplot antara log AI dan Vclay menunjukan zona target memiliki nilai AI lebih tinggi dari shale yang diakibatkan tingginya sementasi. Dari kelima zona target, hanya tiga zona yang dapat dipisahkan berdasarkan nilai AI (TG_1; TG_2; dan TG_3). Masing-masing zona memiliki cutoff AI yang berbeda. Lapisan TG_4 dan TG_5 tidak dapat dipisahkan karena memiliki nilai AI yang overlap dengan lapisan shale. Selain crossplot antara log AI dan Vclay, dilakukan juga crossplot antara log AI dan density-porosity untuk mendapatkan persamaan linearnya. Persamaan linier antara log Density-Porosity dengan AI digunakan untuk memprediksi volume porositas dari volume AI hasil inversi. Karena ketiga zona target memiliki nilai cutoff AI yang berbeda, crossplotpun dilakukan untuk masing-masing zona. Persamaan empiris Castagna digunakan untuk estimasi kecepatan gelombang-S (Vs). Karena persamaan tersebut hanya valid dalam keadaan tersaturasi air 100%, maka dilakukan FRM menggunakan persamaan Biot-Gassmann untuk mendapatkan Vs dalam kodisi sebenarnya. Berdasarkan analisa trend amplitude ditentukan rentang sudut nilai EI near dan far sebesar 00-140 dan 120-220. EI far akan mengalami penurunan yang lebih drastis dari EI near dengan keberadaan hidrokarbon, sehingga crossplot EI near dan far memberikan indikasi keberadaan hidrokarbon. Analisa terintegrasi hasil inversi AI dan EI menunjukan beberapa zona prospektif yang poros dan menunjukan adanya hidrokarbon pada lapangan Moun ====================================================================================================== This research describe the application of acoustic impedance (AI) and elastic impedance (EI) seismic inversion to 3D seismic data in Muon field, Air Benakat formation Jambi sub-basin. There were twelve well log data used which consist six deviated well and six vertical well. AI inversion has been done in order to find porous zone. EI inversion which consider Vs and angle component has been done to detect presence of hydrocarbon. Model Based Hard Constrain method used in either AI or EI inversion. Crossplot between AI and Vclay log show that target zones have a higher AI value than it’s shale. The high AI value may were caused by high cementation. Only three from five zones which could be separated from the shale based on it’s AI value (TG_1; TG_2; and TG_3). Each of them has a different cotoff value of AI. Neither TG_4 nor TG_5 could not be separated from the shale because the AI value were overlap. Beside it, the crossplot have also been done between AI and density-porosity log to aim linear equation. Linear equation between Density-Porosity log and AI log were used to predict porosity volume from AI inversion result. Because the target zones has a different AI’s cutoff value, the crossplot has been done for each zones. Castagna empirical relation were used to estimate shear wave velocity (Vs). Because the Castagna equation only valid in 100% water saturated, Fluid Replacement Modelling (FRM) were used to aim Vs in real condition. Based on amplitude trend analysis range of near and far angle were determined. The range of near EI was 00-140 and 120-220 for far EI. Target zones had a different AI cutoff. Crossplot between near and far EI gave indication of hydrocarbon presence. Integrated analysis from AI and EI result gave some prospective zone which contain hydrocarbon in Muon fiel