Introduction stratigraphy

Stratigraphy, a branch of geology, studies rock layers and layering (stratification). Stratigraphy, from Latin stratum + Greek graphia, is the description of all rock bodies forming the Earth's crust and their organization into distinctive, useful, mappable units based on their inherent properties or attributes in order to establish their distribution and relationship in space and their succession in time, and to interpret geologic history. Stratum (plural=strata) is layer of rock characterized by particular lithologic properties and attributes that distinguish it from adjacent layers.

History of stratigraphy begin by Avicenna (Ibn Sina) with studied rock layer and wrote The Book of Healing in 1027. He was the first to outline the law of superposition of strata:^[1] "It is also possible that the sea may have happened to flow little by little over the land consisting of both plain and mountain, and then have ebbed away from it. ... It is possible that each time the land was exposed by the ebbing of the sea a layer was left, since we see that some mountains appear to have been piled up layer by layer, and it is therefore likely that the clay from which they were formed was itself at one time arranged in layers. One layer was formed first, then at a different period, a further was formed and piled, upon the first, and so on. Over each layer there spread a substance of differenti material, which formed a partition between it and the next layer; but when petrification took place something occurred to the partition which caused it to break up and disintegrate from between the layers (possibly referring to unconformity). ... As to the beginning of the sea, its clay is either sedimentary or primeval, the latter not being sedimentary. It is probable that the sedimantary clay was formed by the disintegration of the strata of mountains. Such is the formation of mountains."

The theoretical basis for the subject was established by Nicholas Steno who re-introduced the law of superposition and introduced the principle of original horizontality and principle of lateral continuity in a 1669 work on the fossilization of organic remains in layers of sediment.

The first practical large scale application of stratigraphy was by William Smith in the 1790s and early 1800s. Smith, known as the Father of English Geology, created the first geologic map of England, and first recognized the significance of strata or rock layering, and the importance of fossil markers for correlating strata. Another influential application of stratigraphy in the early 1800s was a study by Georges Cuvier and Alexandre Brongniart of the geology of the region around Paris.

In the stratigraphy you can find term of

- Stratigraphic classification. The systematic organization of the Earth's rock bodies, as they are found in their original relationships, into units based on any of the properties or attributes that may be useful in stratigraphic work.

- Stratigraphic unit. A body of rock established as a distinct entity in the classification of the Earth's rocks, based on any of the properties or attributes or combinations thereof that rocks possess. Stratigraphic units based on one property will not necessarily coincide with those based on another.

- Stratigraphic terminology. The total of unit-terms used in stratigraphic classification.It may be either formal or informal.

- Stratigraphic nomenclature. The system of proper names given to specific stratigraphic units.

- Zone.Minor body of rock in many different categories of stratigraphic classification. The type of zone indicated is made clear by a prefix, e.g., lithozone, biozone, chronozone.

- Horizon. An interface indicative of a particular position in a stratigraphic sequence. The type of horizon is indicated by a prefix, e.g., lithohorizon, biohorizon, chronohorizon.

- Correlation. A demonstration of correspondence in character and/or stratigraphic position. The type of correlation is indicated by a prefix, e.g., lithocorrelation, biocorrelation, chronocorrelation.

- Geochronology. The science of dating and determining the time sequence of the events in the history of the Earth.

- Geochronologic unit. A subdivision of geologic time.

- Geochronometry. A branch of geochronology that deals with the quantitative (numerical)measurement of geologic time. The abbreviations ka for thousand (103), Ma for million (106), and Ga for billion (milliard of thousand million, 109) years are used.

- Facies. The term "facies" originally meant the lateral change in lithologic aspect of a stratigraphic unit. Its meaning has been broadened to express a wide range of geologic concepts: environment of deposition, lithologic composition, geographic, climatic or tectonic association, etc.

- Caution against preempting general terms for special meanings. The preempting of general terms for special restricted meanings has been a source of much confusion.

SO2 FLUX MEASUREMENT BY DOAS DOAS (DIFFERENTIAL OPTICAL ABSORPTION SPECTROSCOPY) AND ITS APPLICATION AT BROMO ERUPTION ON JUNE 2004

Convention Bandung 2004 (CB2004) The 33^rd Annual Convention & Exhibition 2004

Indonesian Association of Geologist Horizon Hotel, 29-30 Nov, 1 Oct 2004, Bandung

SO2 FLUX MEASUREMENT BY DOAS
DOAS (DIFFERENTIAL OPTICAL
ABSORPTION SPECTROSCOPY) AND ITS
APPLICATION AT BROMO ERUPTION ON
JUNE 2004

Hanik Humaida and Yustinus Sulistyo

BPPTK-Direktorat Volkanologi dan Mitigasi Bencana Geologi

Abstract

SO2 is one of the volcanic gases that can provide information about the state of volcano activity, Commonly, SO2 flux is measured by COSPEC (Correlation Spectroscopy). This equipment has several disadvantages; such as heavy, bog size, expensive and stastic operation only. DOAS (Differential Optical Absorption Spectroscopy) is anew method for SO2 gas flux monitoring that has advantages compares to the COSPEC. Recently, this method has been developed. This DOAS consist of 5 units; namely scan miler, condenser lens, detector, power supply, and a laptop. Its total wieght is up to 11 kg. For operation of DOAS using traverse method, it need lens unit, detector and laptop. The weight is only 2 kg DOAS can be operated as static or traverse method and can be mounted at anyplace.

Measurement of SO2 flux by DOAS has been done at G. Bromo on 12-15 June 2004, after the 8 June eruption. Location of neasurementis about 2 km from eruption source using tripod. This angle of measurement ranges between 10o and 12o width of scan is 45 ^o. Data was analysed by HINAGATA sofware. The result showed that 30 minutes before the volcano produced ash, the flux of SO2 increased from normal condition until 135 ton/day.

Convention Bandung 2004 (CB2004) The 33^rd Annual Convention & Exhibition 2004

Indonesian Association of Geologist Horizon Hotel, 29-30 Nov, 1 Oct 2004, Bandung

SEISMIC HAZARD ASSESSMENT: IN THE
CASE STUDY OF MINESITE AREA-CENTRAL KALIMANTAN

Engkon K. KertapatiGeological

Research and Development Centre,

Abstract

The low-seismicity Central Kalimantan has never experienced any earthquake damage. Thus, earthquake-resistant design has not been specifically required in the building codes. However, it has been realized that urban and mine areas located rather distantly from earthquake sources may also be affected by tremors. The key is basically determined by how well seismic hazards derived from seismic potency can be estimated. In this paper, the potential ground motion in terms of the peak ground accelerations (PGAs) due to long – distance East Kalimantan and West Sulawesi earthquakes (far field earthquake) is investigate, following a probabilistic seismic hazard assessment approach. Earthquakes that have occurred in radius of 500 km (far field) in the last 50 year are used. Based on the PGAs of more than 50% East Kalimantan and West Sulawesi earthquakes recorded in Central Kalimantan, the attenuation relationship of Fukushima and Tanak (1992) is found to correlate well with the high-rate attenuation characteristic of the region. The predicted design basis PGA for Tailings Dam, i.e., PGA with 10% probability of being exceeded in a 20-year exposure time, on rock outcrops site is 0.041 g (g=gravity value), or 0.103 g on soft soil. And 0.105 g with 10% probability of being exceeded in a 1000 year exposure time on rock ou-crops or 0.261 g for soil. However, the increasing number of felt tremors in recent yaers demonstrates suc as: Muarateweh earthquake, which occurred on July 05, 1996, that although no significant damage was report, the earthquake was strongly felt.

Keywords: ground acceleration, ground-motion, attenuation function, earthquake-resistant design.

Convention Bandung 2004 (CB2004) The 33^rd Annual Convention & Exhibition 2004

Indonesian Association of Geologist Horizon Hotel, 29-30 Nov, 1 Oct 2004, Bandung

EXPERIMENTAL STUDY ON
LOCALIZATION OF DEFORMATION
(SHEAR ZONE) ON SATURATED
SANDY SOILS IN RING SHEAR TEST

Muhammad Wafid A N

Directorate of Geology and Mining Area Environmcnt

Abstract

Series of tests on saturated sandy soil under undrained and drained shearing conditions, with various relative densities by means of ring shear apparatus were carried out to investigate the shear zone development process The macroscopic structural observations were conducted through “SOBO method” by capturing the oven-dried samples using a camcorder/digital camera. This observation revealed that for dense sand, the shear zone starts to develop at failure and the thickness increases by progress of shear displacement. While for loose sand no obvious developed shear zone at peak shear strength. In the beginning of shear zone formation, the shape of the shear zone was refined concavely with distinct undulating structure (secondary) which gradually changed to become parallel when shear displacement proceed. Further shearing the shape of shear zone was refined convexly with unrecognizable shear surface. Another interesting phenomenon obtained by this study is that when sandy soils has been sheared until reaching the steady state, the coarse and the fine-particles (including the result of grain crushing) within the shear zone became separated by segregation process. At this state, the core part mainly consisted of coarse grain with very limited fine particles, while the fine particles were accumulated at the bottom part of shear zone.

THE LEMBANG FAULT

Convention Bandung 2004 (CB2004) The 33^rd Annual Convention & Exhibition 2004

Indonesian Association of Geologist Horizon Hotel, 29-30 Nov, 1 Oct 2004, Bandung

THE LEMBANG FAULT

Danny H. Natawidjaja and Djedi S. Widarto

Research Center for Geotechnology-LIPI

Abstract

Lembang fault runs east-west in the northern part of Bandung. This fault zone is clearly seen along its ~25 km section, indicated by a lineament of a marching hills, from the area east of Maribaya resort to the Cisarua-Cimahi region in the west. The tectonic morphologies on and around the fault line indicates that this fault has been active in the Quaternary through the Holocene periods, and probably until recent. The length of the fault implies that this fault may be able to produce an earthquake with a magnitude of 6 to 7. The fault zone that runs through a fairly developed and populated region, and is located just about 15 km north of the highly populated city of Bandung urges to be seriously taken into account for hazard mitigations and for a development planning of the city. We perform geological and morpho-tectonics analyses as well as reviewing previous geological and geophysical data in order to investigate the history, kinematics and activity of the Lembang fault.

CHALLENGES AND REWARDS OF FORMING A DRILLING ALLIANCE IN INDONESIA – A CASE STUDY

PROCEEDINGS, INDONESIAN PETROLEUM ASSOCIATION
Twenty-Eighth Annual Convention & Exhibition, October 2001

CHALLENGES AND REWARDS OF FORMING A DRILLING ALLIANCE IN INDONESIA – A CASE STUDY

Muslim*
Jun Hadisutrisno*
Andrew Swale*
Gary Gauntt**

ABSTRACT

In early 1999 VICO Indonesia recognized that improved teamwork with its major service providers and vendor companies could result in significant reductions in well costs. A study performed by VICO Indonesia drilling and contracts personnel resulted in the implementation of a drilling alliance with VICO’s major service provider. This alliance incorporated the integration of planning, execution and evaluation of the well construction process with a joint project management arrangement based on mutually agreed bottom line goals. The challenges overcome and the results achieved during this project have major implications for the future of operator – supplier relationships in Indonesia.

Historically, contract procedures and legal restrictions in Indonesia have limited the operator – supplier relationship to a tightly structured traditional contractual approach. These restrictions, for the most part, precluded alignment of goals between the operator and supplier. VICO Indonesia and the service provider, however, were able to formulate an innovative approach to overcome these barriers resulting in savings of over US $5.5 million during the drilling of the first eleven wells in the program.

This paper presents a case history of a successful integrated services team in an Indonesian production sharing contract (PSC) organization. The discussion includes details of the contracting approach in addition to the main improvements in the operation that continue to reduce costs.

MANAGEMENT OF OIL AND GAS EXPLORATION AND PRODUCTION IN THE ZAMRUD FIELD, PT CALTEX PACIFIC INDONESIA

PROCEEDINGS, INDONESIAN PETROLEUM ASSOCIATION
Twenty Eight Annual Convention & Exhibition, October 2001

MANAGEMENT OF OIL AND GAS EXPLORATION AND PRODUCTION IN THE ZAMRUD FIELD, PT CALTEX PACIFIC INDONESIA

Arief Yunan*
Bambang Haryanto*

ABSTRACT

Caltex Pacific Indonesia (CPI), a production sharing contractor of Pertamina on the Island of Sumatra, Indonesia, has 141 oil fields covering an area of 35,000 sq km. Current company production is 720,000 barrels oil per day. Zamrud Field is one of the oil fields in the Coastal Plain and Pekanbaru (CPP) Block whose contract will expire in August 2001, and is located within a conservation area.

This paper describes how CPI manages the development of oil and gas production in the Zamrud conservation area. This will benefit those involved in the CPP operations in the future. This project began with a “green” seismic project, “zero discharge” drilling, water management, and preservation of nature, and it continued through delivering oil to the sales point. The challenges come not only from internal issues in preserving the environment during oil field operations, but also from the cultivated surrounding areas that lead to growing pressure on the conservation area.

As global energy demand continues to grow, the oil and gas companies are expanding their exploration and production activities into some of the most sensitive and remote ecosystems. The Zamrud field is one of the sensitive ecosystems where CPI is exploring and producing oil and gas. The history of oil and gas development in sensitive tropical ecosystems has been marked by conflicts with environmentalists and isolated indigenous communities. CPI, however, in line with its vision,mission and values in preserving its area of operation has implemented viable techniques, technologies and innovative management approaches. CPI has also improved communications among companies, governments and local communities. Together, these initiatives have increased the potential to reduce the risks of oil and gas development.

High commitment to the environment, which is reflected in an integrated effort between the government, the company, the local people and other institutions, has resulted in successfully preserving the area. Application of the latest drilling and production technology has contributed to the success in maximizing oil production and at the same time preserving the environment.

This paper concludes that the way CPI manages exploration and production operations has proven to utilize good practices applicable for the future. These have implemented viable techniques to ensure that CPI preserves the environment while exploring for and developing hydrocarbons for the Government of Indonesia.

PROCEEDINGS, INDONESIAN PETROLEUM ASSOCIATION
Twenty-Eighth Annual Convention & Exhibition, October 2001

MULTI-DATABASE MANAGEMENT, AN EXSPAN CASE STUDY

Prajuto*

ABSTRACT

Exspan Nusantara is currently setting up an integrated database management system to improve access and enhance ease of utilization by end-users and database administrators through dedicated personal computers. A number of databases embracing New Venture and Exploration activities including inventory and drafted data are, at present, stored in the different computers (PCs and workstations) with different operating systems (Windows, NT and Solaris) and different vendor applications. A work plan and time schedule to accomplish database integration has been prepared, and comparison studies with other oil and gas operators based in Jakarta is underway. Upgrade of obsolete databases has been accomplished and a master database and browser tool applications have been checked and evaluated. Following implementation of the integrated Exploration Database System, the next step will be to integrate this with existing Engineering and Production databases. Sharing of experience and interaction with other PSC operators and oilfield service contractors is welcome and beneficial to achieve speedy and appropriate establishment of the new system.

A REVIEW OF SUBSURFACE MODELLING IN DIFFERENT INDUSTRIES

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

A REVIEW OF SUBSURFACE MODELLING IN DIFFERENT INDUSTRIES

Ankur Gupta

Paradigm, Mumbai, India.
ankurg@pdgm.com

ABSTRACT

As the world’s demand for oil, gas, coal and minerals increases it becomes more and more important to image the subsurface and to predict its behaviour in response to changes in stress and fluid movement. The requirements of different subsurface industries can be very different but the overlap is significant. This paper considers opportunities for collaboration across industries, identifies barriers and discusses successful technology transfers.