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"Andesitic and basaltic lavas are the main product of the upper Miocene volcanic activities in Lubuk Sikaping region. They posses vesicular and amygdales structure, dark grey to black in colour, highly porphyritic in texture composed of plagioclase, clinopyroxene, orthopyroxene, olivine (in basalt only) and minor hornblende, magnetite and ilmenite. They (basalt and andesite) mostly fall within the calc-alkaline series on the AFM. The basalt and andesite are not primary magma since they have low Mg# and Ni contents. The lavas resemble the typical of arc setting with Nb through on the spider-diagram patterns, enrichment in large ion lithophile elements and light rare earth elements relative to high field strength elements and heavy rare earth element. They are co-magmatic as shown by the REE pattern. The lavas have high concentration of Ba, Sr, La, Rb and Ce, Zr, Th and U, and high Ba/La ratio which indicating an involvement subducted sediment in their generation. The lava from Lubuk Sikaping is product of Maninjau Crater eruption in Upper Miocene. This lava was uplifted and exposed on high level topography for a few million years, and then superimposed by a high-K calcalkaline volcanic of mainly rhyolitic tuff as a result of the reactivation of the Maninjau Crater in Pleistocene."

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ABSTRACTThis book provides a comprehensive introduction to the field of geochemistry. The book first lays out the 'geochemical toolbox': the basic principles and techniques of modern geochemistry, beginning with a review of thermodynamics and kinetics as they apply to the Earth and its environs. These basic concepts are then applied to understanding processes in aqueous systems and the behavior of trace elements in magmatic systems. Subsequent chapters introduce radiogenic and stable isotope geochemistry and illustrate their application to such diverse topics as determining geologic time, ancient climates, and the diets of prehistoric peoples. The focus then broadens to the formation of the solar system, the Earth, and the elements themselves. Then the composition of the Earth itself becomes the topic, examining the composition of the core, the mantle, and the crust and exploring how this structure originated. A final chapter covers organic chemistry, including the origin of fossil fuels and the carbon cycle's role in controlling Earth's climate, both in the geologic past and the rapidly changing present.Geochemistry is essential reading for all earth science students, as well as for researchers and applied scientists who require an introduction to the essential theory of geochemistry, and a survey of its applications in the earth and environmental sciences.Additional resources can be found at."

"Di lapangan AA, metoda seismik inversi digunakan untuk menghasilkan volume akustik impedansi. Hasil dari metode ini tidak hanya menghasilkan resolusi yang lebih baik untuk interpretasi struktur yang lebih akurat , tetapi juga memberikan pengertian lebih baik tentang prediksi sifat-sifat fluida dan resrevoar. Seismik inversi AVO merobah seismik data menjadi P-impedansi (hasil dari densitas dan kecepatan gelombang-P), S-impedansi (hasil dari densitas dan kecepatan gelombang-S), dan densitas (ρ) yang menjadikan pemisahan fluida dan litologi menjadi lebih baik. Sebelum membahas AVO inversi, reservoar fisika batuan dianalisa untuk tujuan Fluid Replacement Modeling (FRM). Melalui FRM, dilakukan pertukaran fluida menggunakan persamaan Biot Gassmann untuk mengetahui pengaruh fluida pada sifat-sifat elastik batuan. Awalnya, Vp, Vs, ρ dan Sw dari suatu fluida harus diketahui. Kemudian, hasil analisa dibawa memalui perbandingan antara sumur seismogram sintesa dari fluida yang berbeda atau sifat-sifat batuan dengan data seismik menggunakan hasil ekstraksi wavelet. Perbedaan fluida dengan perbedaan sifat-sifat batuan menunjukkan perbedaan respons amplitudo dan karakternya. Hasil studi ini diharapkan memperkuat interpretasi seismik untuk pemisahan fluida dan litologi. Selanjutnya, melalui studi diharapkan dapat digunakan untuk mengoptimalkan produksi oil dan gas dan di lapangan AA.

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At AA Field, we applied seismic AVO inversion methods to generate acoustic impedance volume. The results of this approach provide not only better resolution for more accurate structural interpretations, but also allow us to perform better fluids and reservoir properties predictions. Seismic AVO inversion transforms seismic data into P-impedance (product of density and P-wave velocity), S-impedance (product of density and S-wave velocity), and density (ρ) for better discrimination on fluid and lithology effects. Prior to AVO Inversion, rock physics of the reservoir were analyzed for Fluid Replacement Modeling (FRM) purposes. Through this FRM, we employed Biot Gassmann fluid substitution to investigate fluid effects on rocks elastic properties. Initially, we setup input logs of Vp, Vs, ρ, and fluid saturation (Sw) with known fluid type. Later on the workflow, analysis was carried-out through comparison between well synthetic seismogram of different fluids or rock properties with seismic data using extracted wavelet. Different fluid with different rock properties exhibit different amplitude responses and characters. This study has enhanced our seismic interpretation for fluid and lithology discriminations. Furthermore, this study can be used for optimization of oil and gas productions at AA Field."

"Summary:Presents the essentials of both Mineralogy and Petrology through an approach accessible to industry professionals, academic researchers, and students. This book includes detailed knowledge of minerals and rocks and the process of formation and association that are essential for practicing professionals and advanced students"