[ABSTRAK Lapangan XXX merupakan lapangan minyak di cekungan Natuna Baratdengan reservoir utama berupa reservoir batu pasir. Ketebalan reservoir padalapangan ini sangat bervariasi sehingga hasil inversi hanya dapat memetakanketebalan reservoir yang mendekati ketebalan tuning.Berdasarkan uji sensitifitas, parameter AI di setiap sumur tidak dapatmembedakan hidrokarbon, sehingga parameter akustik saja tidak dapat diaplikasikandalam karakterisasi reservoir lapangan ini. Namun ketika parameter densitas terpisahdengan parameter kecepatan P, sebaran hidrokarbon dapat dibedakan dengan baik.Kecepatan S tidak tersedia di semua sumur padahal data ini sangat diperlukanuntuk melakukan pengolahan data dengan metode inversi simultan. Oleh karena ituakan dilakukan beberapa estimasi untuk mendapatkan data kecepatan S antara laindengan metode castagna, metode gassmann, metode parsial, metode Xu-White danmetode Lee. Data kecepatan S yang dipakai adalah kecepatan S terbaik yangdiperoleh dari metode Xu White dikarenakan hasil log poisson’s rationya palingmendekati tren kurva saturasi air. Selain itu aspek rasio batuan yangmempertimbangkan nilai porositas dan volume clay, serta kontrol kualitas Vp modeldari metode Xu-White memiliki rasio error minimum jika dibandingkan dengan nilaiVp dari data log.Metode inversi simultan dengan data pre-stack atau partial stackmemungkinkan dilakukannya prediksi parameter Impedansi P, Impedansi S, dandensitas dari data seismik. Selain itu meode inversi simultan dapat dipergunakanmulti wavelet dalam pengolahan datanya. Hasil penampang inversi yang diperolehmenunjukkan bahwa inverse densitas dapat menjelaskan letak sebaran batuanreservoir dan fluida berdasarkan cut off sensitifitas yakni nilai dibawah 2,26 gr/cc. ABSTRACT field is an oil field in West Natuna Basin with sandstone reservoir asprimary target. There was varying reservoir thickness, so the inversion method thatcould only be applied to map reservoir thickness, which close to tuning thickness.Based on sensitivity analysis, Acoustic Impedance parameters couldn’tindicate hydrocarbon appearance for each well, so Acoustic Impedance cannot beapplied for reservoir characterization in this field. Density versus AcousticImpedance could map hydrocarbon appearance.Shear velocity weren’t available where those data was needed for runningsimultaneous inversion method. Predicting velocity shear would be carried out byusing several method such as Castagna, Gassmann, Parsial, Xu-White, and Lee. Thebest estimated velocity shear would be used for inversion, The best estimated shearvelocity from Xu-White method because Xu-White’s poisson ratio log presentssimilar trend with water saturation log (Sw). Moreover, Xu-White’s ratio aspect isalso considering porosity and clay volume value. Based on quality control result, Vpmodel of Xu-White had minimum error ratio compared to Vp from log.Simultaneous inversion with pre-stack and parsial stack data what can be usedfor predicting P-Impedance, S-Impedance, and density from seismic data. Otherwise,this method is also used not only for single wavelet but also multi wavelet. Theinversion result from this study can mapping out the hydrocarbon appearance forreservoir target based on cut off value from sensitivity test of less than 2,26 gr/cc.;X field is an oil field in West Natuna Basin with sandstone reservoir asprimary target. There was varying reservoir thickness, so the inversion method thatcould only be applied to map reservoir thickness, which close to tuning thickness.Based on sensitivity analysis, Acoustic Impedance parameters couldn’tindicate hydrocarbon appearance for each well, so Acoustic Impedance cannot beapplied for reservoir characterization in this field. Density versus AcousticImpedance could map hydrocarbon appearance.Shear velocity weren’t available where those data was needed for runningsimultaneous inversion method. Predicting velocity shear would be carried out byusing several method such as Castagna, Gassmann, Parsial, Xu-White, and Lee. Thebest estimated velocity shear would be used for inversion, The best estimated shearvelocity from Xu-White method because Xu-White’s poisson ratio log presentssimilar trend with water saturation log (Sw). Moreover, Xu-White’s ratio aspect isalso considering porosity and clay volume value. Based on quality control result, Vpmodel of Xu-White had minimum error ratio compared to Vp from log.Simultaneous inversion with pre-stack and parsial stack data what can be usedfor predicting P-Impedance, S-Impedance, and density from seismic data. Otherwise,this method is also used not only for single wavelet but also multi wavelet. Theinversion result from this study can mapping out the hydrocarbon appearance forreservoir target based on cut off value from sensitivity test of less than 2,26 gr/cc., X field is an oil field in West Natuna Basin with sandstone reservoir asprimary target. There was varying reservoir thickness, so the inversion method thatcould only be applied to map reservoir thickness, which close to tuning thickness.Based on sensitivity analysis, Acoustic Impedance parameters couldn’tindicate hydrocarbon appearance for each well, so Acoustic Impedance cannot beapplied for reservoir characterization in this field. Density versus AcousticImpedance could map hydrocarbon appearance.Shear velocity weren’t available where those data was needed for runningsimultaneous inversion method. Predicting velocity shear would be carried out byusing several method such as Castagna, Gassmann, Parsial, Xu-White, and Lee. Thebest estimated velocity shear would be used for inversion, The best estimated shearvelocity from Xu-White method because Xu-White’s poisson ratio log presentssimilar trend with water saturation log (Sw). Moreover, Xu-White’s ratio aspect isalso considering porosity and clay volume value. Based on quality control result, Vpmodel of Xu-White had minimum error ratio compared to Vp from log.Simultaneous inversion with pre-stack and parsial stack data what can be usedfor predicting P-Impedance, S-Impedance, and density from seismic data. Otherwise,this method is also used not only for single wavelet but also multi wavelet. Theinversion result from this study can mapping out the hydrocarbon appearance forreservoir target based on cut off value from sensitivity test of less than 2,26 gr/cc.] |