Introduction geology

From Wikipedia, the free encyclopedia

Geology (from Greek: γη, gê, "earth"; and λόγος, logos, "speech" lit. to talk about the earth) is the science and study of the solid matter that constitutes the Earth. Encompassing such things as rocks, soil, and gemstones, geology studies the composition, structure, physical properties, history, and the processes that shape Earth's components. It is one of the Earth sciences. Geologists have established the age of the Earth at about 4.6 billion (4.6x10⁹) years, and have determined that the Earth's lithosphere, which includes the crust, is fragmented into tectonic plates that move over a rheic upper mantle (asthenosphere) via processes that are collectively referred to as plate tectonics. Geologists help locate and manage the Earth's natural resources, such as petroleum and coal, as well as metals such as iron, copper, and uranium. Additional economic interests include gemstones and many minerals such as asbestos, perlite, mica, phosphates, zeolites, clay, pumice, quartz, and silica, as well as elements such as sulfur, chlorine, and helium. Geology is also of great importance in the applied fields of civil engineering, soil mechanics, hydrology, environmental engineering and geohazards.

Planetary geology (sometimes known as Astrogeology) refers to the application of geologic principles to other bodies of the solar system. Specialised terms such as selenology (studies of the moon), areology (of Mars), etc., are also in use. Colloquially, geology is most often used with another noun when indicating extra-Earth bodies (e.g. "the geology of Mars").

The word "geology" was first used by Jean-André Deluc in the year 1778 and introduced as a fixed term by Horace-Bénédict de Saussure in the year 1779. The science was not included in Encyclopædia Britannica's third edition completed in 1797, but had a lengthy entry in the fourth edition completed by 1809.An older meaning of the word was first used by Richard de Bury to distinguish between earthly and theological jurisprudence.

PROCEEDINGS JOINT CONVENTION BALI 2007
The 32^nd HAGI, the 36^th IAGI, and The 29^th IATMI Annual Convention and Exhibition

ROCK PHYSICS ANALYSIS FOR FEASIBILITY OF AVO AND INVERSION
STUDIES: A TOOL FOR EXPLORATION STRATEGY IN JABUNG BLOCK

Woro Sutjiningsih¹, M. Noor Alamsyah¹, Lambok P. Marpaung¹, I Nyoman Suta¹,
Tigor Siagian¹, Ari Subekti², Pandu Patria³, Fatkhan⁴

¹PetroChina International Jabung Ltd
²Brunei Shell Petroleum Co. Sdn. Bhd.
³Alliance Geotechnical Solutions
⁴Institute of Technology Bandung

ABSTRACT

Jabung Block, in the northern edge of the South Sumatra Basin, actively explored since 1993 and currently operated by PetroChina. More than 200 wells have been drilled, producing average of 60,000 BOEPD from multiple different reservoirs. The present block boundary remains 20% (1642 sqkms) of its original after the final relinquishment in 2003, adds challenges of exploration strategy having narrow and mature block. To overcome this issue, advance seismic approaches such as Seismic Multi Attribute, AVO, Inversion, and AVO-Inversion, should be applied instead of conventional interpretation. This technique can not be applied homogenously and should follow the characteristic of each field in different formation targets. The Rock Physics analysis has been investigated for feasibility reservoir as well as hydrocarbon characterization covers entire Jabung area.

Rock physics analysis conducted by using electrical log data of around 50 assigned wells distribute and represent all different provenance area in the block. The study focused on lithology differentiation and hydrocarbon response to seismic data by deriving physical properties parameter from log data such as Impedance, Lame constant (Lambda and Mu), Bulk Modulus, Poisson Ratio, and Elastic Impedance in constant angle. Logs were cross-plotted to define facies correspond to reservoir/ or non-reservoir and correspond to hydrocarbon versus non-hydrocarbon. Hydrocarbon response analysis using by Zoeppritz equation was also applied to see AVO response. The result then mapped to see the Jabung reservoir (sand) distribution defined by rock physics parameter and AVO classes.

The result shows that different field with different formation targets in Jabung Block may have different rock physics parameter. AVO responses are also unique in different provenance/ region. Study result will then assist exploration strategy of using this proper technique to define sand distribution and hydrocarbon response in seismic data out of existing fields. It has been applied to convince and rank potential prospects exist in the area.

RESERVOIR CHARACTERIZATION IN KARANGBARU FIELD USING SIMULTANEOUS INVERSION

PROCEEDINGS JOINT CONVENTION BALI 2007
The 32^nd HAGI, The 36^th IAGI, and The 29^th IATMI Annual Conference and Exhibition

RESERVOIR CHARACTERIZATION IN KARANGBARU FIELD
USING SIMULTANEOUS INVERSION

Mualimin¹, Arif Prasetyo H², Rizaq Faidul H3

¹PT. PERTAMINA EP Region Jawa, Formerly Paradigm Indonesia.
²PT^. PERTAMINA EP Region Jawa,
³PT. Chevron Pacific Indonesia, Formerly Paradigm Indonesia on-site
PT. PERTAMINA EP Region Jawa.

EXTENDED ABSTRACT

Karangbaru Field is exploration field with respect to hydrocarbon exploration and exploitation, with 2 wells drilled to date. The fields has potential for additional gas reserves, although in more subtle traps with high risk.

The methodology integrates several processes-from seismic data acquisition through the three- dimensional visualization of the geo-bodies obtained by the simultaneous inversion of the data, using petrophysical information derived from the wells and rock model to predict the elastic properties. New 3D seismic was acquired to identify potential prospects. The design, acquisition, and processing parameters were determined by modeling the AVO response and geometry of possible reservoirs derived from VSP studies and well logs. The inversion process is carried out by inverting the prestack seismic data using a linear approach. These data have been reprocessed and prestack-migrated using a preserved amplitude sequence. The simultaneous inversion is based on the Fatti modification of the Aki-Richards equation, applied to seismic gathers with angles up to 30° . The inversion results such as P-impedance, S- impedance, and the Vp/Vs relationship transformed to the elastic attributes lambda-rho (ëρ), mu-rho (µρ) and Fluid Factor which are used to predict the distribution of sand geobodies through the volume, based on user-defined cutoff values of the ëρ and µρ parameters.

The integration of seismic, geologic, and data from existing wells is carried out through the simultaneous inversion of pre stack time-migrated data. The visualization of the geobodies with the attributes P-wave impedances, lambda-rho, mu-rho and fluid factor allows identification of optimum areas for future wells. The results have been used to define the locations of new development wells; this has decreased the risk associated with the search of additional gas reserves in the Karangbaru Field.

PROCEEDINGS JOINT CONVENTION BALI 2007
The 32^nd HAGI, The 36^th IAGI, and The 29^th IATMI Annual Conference and Exhibition

GEOPOTENCY PROSPECT OF BLAMBANGAN PENINSULA
AS SUPPORTER FOR CONSERVATION DEVELOPMENT
IN ALAS PURWO NATIONAL PARK, EAST JAVA

12 3

Riki Suputra , Hatma Suryatmojo , Srijono

1

Junior geologist, alumni of Geological Engineering, UGM 55281, riki_suputra@yahoo.com

2

Jurusan Konservasi Sumberdaya Hutan, FKHT, UGM

3 Dynamic Geology Laboratory, Geological Engineering, UGM 55281

ABSTRAK

Blambangan Peninsula, East Java, known as Karst Blambangan, come within in Alas Purwo National Park which conservated. Karst area is very potential on natural resources, but it is also a susceptible ecosystem. Besides Geopotency as a resources and also a kind of possible disaster (hazard) which exist in peninsula, it expected to support the development of national park conservation.

The Research apply the field observation methods, going through the trajectory encircle the coastal area, and exploration finding the cave and wellspring. the laboratory Analyze include the petrography, equiped by the chemical analysis for the limestone and water.

Geopotency of Blambangan Peninsula consist of resource: karst topography, industrial dig substance, karst hydrology, coastal area -coastal with the sea wave. Forming of karst topography consist of the micro karst, minor, major, eksokarst, and endokarst. Typical of endokarst is 23 minimum founded cave, include vertical cave with 100 m minimum alley. Those area identify the deposit limestone, andesite, and sirtu. Forming of karst spring controlled by fault, with 12 minimum founded location, 3 potency debit location > 1 litre / second, and for the drinking water, 6 location of it contain the concentration of Chromium and Arsen exceed the permanent boundary sill quality. The appearance of River sub-surface below Istana Cave, become a surface river, and water consumed by society in Fount. The sea wave in Plengkung Coast exploited for surf, and as coastal tourism object – coastal area. Kind of possible disaster in peninsula is the collapse of roof cave, environmental contamination, and tsunami.

National Park of Alas Purwo is the primary forest, conservated, with 19 minimum bamboo species specification, sawo kecik which had old age for hundred years, nyamplung tree; animal asylum: Java bull, deer, and peacock. To optimalyze the conservation efforts, the support of geopotency is needed as a place for the growth of plants and animal. Not only for that but it can also develop the potency of tourism in in the Alas Purwo National Park.

Keyword : Blambangan peninsula, Geology, Geopotency, potency ,karst hydrology, National Park of Alas purwo, karst Blambangan

PROCEEDINGS JOINT CONVENTION BALI 2007
The 32^nd HAGI, The 36^th IAGI, and The 29^th IATMI Annual Conference and Exhibition

KINEMATICS MOTION OF WESTERN PART OF SULAWESI REGION
AS DERIVED BY GPS RESULTS

D.A. Sarsito ⁽¹⁾, H.Z. Abidin ⁽¹⁾, H. Andreas⁽¹⁾,
W. Triyoso⁽²⁾, and M.I.T. Taib⁽³⁾

Institute Technology Bandung, Indonesia

⁽¹⁾ Geodesy Research Division, Faculty of Civil and Environmental Engineering,
⁽²⁾ Geophysical Research Division, Faculty of Earth Sciences and Mineral Technology
⁽³⁾ Geophysical Engineering Research Division, Faculty of Earth Sciences and Mineral Technology

e-mail : dsarsito@gd.itb.ac.id
ABSTRACT

The island of Sulawesi is located at the triple juction of the Indo-Australian, Pacific and Eurasion Plates. This triple junction generated a complicated configuration of active plate boundaries with rapid micro- block rotations character. Moreover, since the relative motions of the involved plates are rapid, the area displays a lot of seismicity. Hence the problem of a better understanding of the seismotectonics of the main active structures of the area is of first importance. A dense GPS network was measured yearly since 1997 until 2006. The aim of the current study is to better define the present-day kinematics of western part of Sulawesi and to monitor the Palu-Koro fault to understand finely the interseismic behaviour.

In order to explore these problems, we try to use several GPS mapping approaches (global, regional or sub-regional) to recognize the true tectonic motion in ITRF-2005 and try to model the GPS velocities as resulting from combination of rigid block rotations and elastic deformation linked with the interseismic loading on faults. The best GPS approach is chosen base on the most realistic quality of the coordinate repeatibilities and velocities. For relatively small area, the regional and sub-regional approaches gave the best results since the global approach gave more error propagation effects that make the true deformation signal become not clear. And from these strategy, we invers the results including earthquake slip vector in the Euler vector describing the blocks motions, the faults locations, velocities and the locking depth. Four blocks of motion are used to define the area of investigation based on the geological a priori information. The results shows the North-Sula block rotate clockwise to accommodate the motion of Palu-Koro . The Palu-Koro Fault zone accomodate 42 mm/yr and shows a transtensive behaviour more complex than commonly describe, where this area also have monitored by several GPS continuous stations. And the Makassar block show an individualized anticlockwise motion with respect to Sunda Block, and come finally deaden in Borneo, where smaller deformation is inferred. All these results are usefully for better understanding of kinematics motion the area of investigation.

Key word : Sulawesi, GPS

NEW INFORMATION FROM SEISMIC ATTENUATION TOMOGRAPHY: APPLICATION TO GUNTUR VOLCANO

PROCEEDINGS JOINT CONVENTION BALI 2007
The 32^nd HAGI, The 36^th IAGI, and The 29^th IATMI Annual Conference and Exhibition

NEW INFORMATION FROM SEISMIC ATTENUATION
TOMOGRAPHY: APPLICATION TO GUNTUR VOLCANO

Sri Widiyantoro1, Awali Priyono1, Gede Suantika2, Evandi S. Tambunan3, and Andi M.
Adiwiarta3

1Geophysics Research Group, Faculty of Mining and Petroleum Engineering, ITB
2 Study Program of Earth Sciences, Graduate School, ITB
3Study Program of Geophysics, Faculty of Earth Sciences and Mineral Technology, ITB

ABSTRACT

Travel time tomography has become a standard seismological tool for investigating the velocity structure of large tectonic features and volcanoes. More recently, there has been developments in using attenuation tomography (3D mapping of amplitude decay of seismic waves) to gain more information about the physical make-up of these structures. Studies of seismic travel time tomography on regional and local scales for Indonesia have been performed by previous researchers. On the other hand, a comprehensive study of attenuation tomography that exploit the amplitude data has not been done yet. Therefore, we are motivated to carry out a study on seismic attenuation tomography. Here, the Guntur volcano is chosen due to its present-day high seismic activity, long eruption history and its location i.e. close to the densely populated tourist city of Garut in West Java.

The main objective of this study is to construct 3D seismic attenuation models of the Guntur volcano by utilizing seismograms from recent investigations. We have inverted two data sets taken from two separated observation periods. The results have provided a 4D model of the seismic internal structure of the Guntur volcano. The striking observation is that low velocity anomalies that may represent the distribution of magma are associated with strong low Q (high attenuation) anomalies.