Changes

[[File:Comparison of reservoir rock types.jpg|700px|thumbnail|center|Figure 8- Comparison of reservoir rock types around the world in 1956 (based on Knebel & Rodriguez, 1956 in Koesomadinata, 1980)]]

[[File:Comparison of reservoir rock types.jpg|700px|thumbnail|center|Figure 8- Comparison of reservoir rock types around the world in 1956 (based on Knebel & Rodriguez, 1956 in Koesomadinata, 1980)]]

Volcanic rocks are igneous rocks that formed on the earth surface (extrusive igneous rock). Volcanic rock can be formed from mafic minerals such as olivine, pyroxene, amphibole, and biotite, or felsic minerals such as feldspar, muscovite, and quartz.<ref> Noor, D., 2009, Pengantar Geologi, Universitas Pakuan Bogor.</ref> For example, oil obtained in Jatibarang (West Java, Indonesia), produced from fractures that occur in volcanic rock (tuff). Oil production from volcanic rock reservoir shows higher production in initially, and then shows a rapid decline in production.

Volcanic rocks are igneous rocks that formed on the earth surface (extrusive igneous rock). Volcanic rock can be formed from mafic minerals such as olivine, pyroxene, amphibole, and biotite, or felsic minerals such as feldspar, muscovite, and [[quartz]].<ref> Noor, D., 2009, Pengantar Geologi, Universitas Pakuan Bogor.</ref> For example, oil obtained in Jatibarang (West Java, Indonesia), produced from fractures that occur in volcanic rock (tuff). Oil production from volcanic rock reservoir shows higher production in initially, and then shows a rapid decline in production.

==References==

==References==