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Scientific Contributions Oil and Gas
Published by LEMIGAS
ISSN : 20893361     EISSN : 25410520     DOI : -
Core Subject : Science, Engineering,
Chemical Engineering, Chemistry & Bioengineering Energy
The Scientific Contributions for Oil and Gas is the official journal of the Testing Center for Oil and Gas LEMIGAS for the dissemination of information on research activities, technology engineering development and laboratory testing in the oil and gas field. Manuscripts in English are accepted from all in any institutions, college and industry oil and gas throughout the country and overseas.
Arjuna Subject : Energi (semua kategori) - Teknologi Bahan Bakar
Articles 619 Documents
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Seismic-Derived Rock True Resistivity (R) Revisited. Part I: Reformulation Of Combined Gassmann – Shaly Sand Models Bambang Widarsono; Merkurius F Mendrofa
Scientific Contributions Oil and Gas Vol 29 No 2 (2006)
Publisher : Testing Center for Oil and Gas LEMIGAS

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.29017/SCOG.29.2.867

Abstract

The last decade has observed frantic efforts by geoscientists to extract as much information as possible from seismic data. From the traditional role of establishing subsurface structural geometry, seismic processing and interpretations have evolved into an ever increasing role in providing rock physical properties such as acoustic impedance (AI) and porosity (0). The more common use of 3-D seismic surveys, in both exploration and development stages, have fur- ther underlined the role of seismic data as provider of inter-well rock property data. Further developments in the petrophysics-related seismic interpretation have also shown efforts to ex- tract information related to contents of formation rocks. From the widely acknowledged brightspot analysis for detecting presence of gas-bearing porous rocks in the last decades of the 20 century to the later efforts to extract information regarding fluid saturation in reservoir. Actually, as early as in mid- 1960s have scientists started to investigate the relations between acoustic signals and fluid saturation (e.g King, 1966; Domenico, 1976; Gregory, 1976). However, due to the fact that the then commonly used of 2-D seismic was considered as having insuf- ficient resolution for any practical uses in the field, the efforts remained mainly for academic purposes only. Rapid developments in technology of 3-D seis- mic survey and processing, as well as its more com- mon use at present have prompted attentions back to the investigations aimed at extracting fluid saturation information from seismie data. In 1990s have Widarsono and Saptono (1997) started a series of investigation through laboratory measurements and modeling using core samples. This was followed by more works not only at laboratory level but at larger levels of well and field scales (e.g. Widarsono & Saptono, 2000a, 2000b, and 2001; and Widarsono et al, 2002a, 2000b). Other investigators (e.g. Furre & Brevik, 2000; Wu, 2000; Zhu et al, 2000; and more recently Wu et al, 2005) have also devoted some works to achieving the same goal. Other paths of development have incorporated other supporting tech- niques such as non-linear regression (e.g.Balch et al, 1998) and artificial neural network (e.g. Poupon & Ingram, 1999; Oldenziel et al, 2000).From various investigations using seismic waves as the sole data for fluid saturation extraction, short- comings were soon felt in the form of 'narrow bands' of acoustic signals (ie P-wave velocity, V, and acoustic impedance, AI) that are influenced by varia- tions in fluid saturation. In other words, V, and AI are not too influenced by variation in fluid saturation. This reduces the effectiveness of seismic-derived V and Al as fluid saturation indicators. Efforts were then devoted to link V, and AI to other parameters such as rock true resistivity (R), a parameter known to be very sensitive to variation in fluid saturation. Widarsono and Saptono (2003, 2004) provide laboratory verifications and first field trial with some degree of succes. However, certain assump- tions (i.e. constant/uniform porosity) in the theoreti- cal formulation were still adopted in the above works, which in turn reduced the validity of the resulting formula produced and used. In this paper, the first part of a three-part work, is devoted to reformulating the combination of Gassmann theory and shaly sand water saturation models of Poupon and Hossin. These are to replace the shale-free Archie model used in the above works, which is considered as invalid for most field uses. With this reformulation, it is hoped that a more robust model/formula of resistivity as a function of acoustic impedance (R, = fAI)) is achieved, hence a more reliable resistivity could be extracted from seismic- derived acoustic impedance. Summarily, the objectives of the works a part of them presented in this paper are - To establish a model/method to obtain formation rock true resistivity (R) from seismic-derived acoustic impedance (AI), and To provide correction/modification onto previous works reported in Widarsono & Saptono (2003, 2004).
Selective Hydrocracking Of Heavy Distillate To High Viscosity Index Lube Base Stock By Using Bi-Functional Catalysts A.S Nasution
Scientific Contributions Oil and Gas Vol 28 No 1 (2005)
Publisher : Testing Center for Oil and Gas LEMIGAS

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.29017/SCOG.28.1.869

Abstract

Hydroprocessing is the catalytic reaction of hydrogen with petroleum or other hydrocarbon materials. It may be carried out for a variety of objectives, including: saturation of olefins or aromaties, molecular rearrangement, or removal of impurity (1).Selective hydrocracking is one of this hydroprocessing to convert higherboiling distillate to lube base stock using a bi-functional catalyst containing both acid site and metal site. Those two active sites of bi-functional catalyst should promote the correct combination of hydrogenation, isomerization and limited hydrocracking function, resulting in the maximum yield of product in the lube oil range (2). The kinetics of this selective hydrocracking greatly depends on the operating conditions: such as feedstock composition, type of catalyst, temperature, pressure, hydrogen to hydrocarbon ratio, and space velocity (6).The versatility of the hydroconversion process with respect to the variety of feedstock are case to study: i.e. the feasibility of the hydroconversion of obtaining lube base stock from heavy distillate.In order to gain more information, an experiment has been carried out to study the selective hydrocracking of vacuum distillate (paraffinic and non paraffinic) by using bifunctional catalysts with various acidity at the following operating conditions: temperature: from 380 to 410 ° C, pressure: 100 kg/cm2 and hydrogen to hydrocarbon ratio: 1000 l/lt. A catatest unit operated in a continuous system was used in this experiment.Gas and liquid product samples were taken from gas and liquid samples, respectively. Liquid product was fractionated to get the following cuts: IBP-380°C and>380°C with 30 theoretical plate fractionator, operating at 4/1 reflux ratio. The >380°C bottom product was treated by dewaxing, using methylisobutyl ketone as a solvent to obtain the lube base stock and wax.
Development Of A Streamline-Based Heat Transport Model For Thermal Oil-Recovery Simulation Usman Usman; Norio Arihara
Scientific Contributions Oil and Gas Vol 28 No 2 (2005)
Publisher : Testing Center for Oil and Gas LEMIGAS

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.29017/SCOG.28.2.870

Abstract

Fluid transport calculations based on streamlines have been used successfully for years to model two-phase in compressible flow simulations", The pressures for defining the streamlines are obtained by assuming that the reservoir fluids and rock are incompressible and that flow is in the steady state, which yields a time-independent equation that can be solved to define the fixed pressure distribution. Streamline tracking is performed with the pressure field to advance saturations or compositions. In this approach, the changing pressure field and the movement of fluids are not tightly connected, which results in inaccuracies in the solution.The streamline approach has recently been extended to various applications, such as compositional and black oil problems for updating the composition and saturation, In cases, a non-linear equation for the pressure is solved assuming unsteady-state flow but compressible fluids and rock, followed by solving the conservation equations in sequence or fully implicitly, i.e. the pressure and the saturation equations are solved together along each streamline. In this approach, most of the physical parameters that depend on the pressure changes are accounted for throughout the solution.The major limitation of the streamline method is that applicability is restricted to convective problems only. In practice, the contribution of physical diffusion due to gravitational and capillary forces must be considered in modeling a reservoir undergoing a displacement process. The model including diffusion cannot be solved using one dimensional (1D) streamlines. The operator splitting technique has been proposed to avoid this restriction, The idea is to isolate the convective flow from the diffusion due to gravity for separate solution. The first part is calculated along the common streamline trajectories and the second part is determined by the direction of gravity.Based on recent advances in streamline based simulation techniques, we have extended the methods to the thermal oil-recovery simulation. Modeling thermal processes is difficult due to the many complex mechanisms, high degree of non-linearity, and requirements for appropriate thermodynamic formulation to account for the changes in properties with temperature and pressure. The present study approached the problem from a different angle in the streamline framework. An operator splitting technique was applied to handle the heat diffusion due to gravity, capillary, and conduction effects, and the implicit method was used for solving the highly non- linear convective streamline and diffusive equations. A practical rule was introduced to select the time step for pressure updates to reduce the time-lag effects on the coefficients in the phase conservation equations.A sequential thermal simulator, which solves the pressure and heat equations sequentially, was developed and tested for simulations of hot water-flooding in heavy-oil reservoirs. First we performed simulation with a two dimensional (2D) heterogeneous reservoir to evaluate the main characteristics of the streamline method such as the number of streamlines, the grid refinement along the streamlines, and the time step size. Then we performed three-dimensional (3D) simulation to examine how the gravity mechanism affects the production performance. The solutions obtained using a commercial thermal simulator were used to compare and validate the developed model.
Development Of Waterflood Profile Modification Using Brightwater Technology Sugihardjo Sugihardjo
Scientific Contributions Oil and Gas Vol 28 No 3 (2005)
Publisher : Testing Center for Oil and Gas LEMIGAS

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.29017/SCOG.28.3.871

Abstract

Water flooding, in many mature fields is facing a common problem of low sweep efficiency in the late production period. The breakthrough of injection water is very early when high permeability streaks or thief zones exist in the formation, and resulted in excessive water production. Two kind of technologies commonly are used to modify the permeability streak i.e. MPM (Microbial Profile Modification), and polymer gel with cross linkers material. A new technology which is called Bright Water has been intensively studied. Bright Water is capable of in-depth placement into high permeability streaks in the reservoir. To improve the water flood sweep efficiency, studies of examination a fluid injection design have been evaluated. The objective of this study is to set-up core flooding tests and to determine the effective- ness of the Bright Water to reduce the permeability, and also include optimization of Bright Water formulation, resistance factor determination, and gelling time evaluation.
Fuzzy Logic As A Tool For Estimating Production Potential Of A Sand Layer Bambang Widarsono; Heru Atmoko; Fakhriyadi Saptono; Tunggal Tunggal; Ridwan Ridwan
Scientific Contributions Oil and Gas Vol 27 No 3 (2004)
Publisher : Testing Center for Oil and Gas LEMIGAS

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.29017/SCOG.27.3.872

Abstract

In production management, a prior knowledge over production potential of a candidate sand layer (geological complexity in Indonesia has led to existence of stratified reservoirs with a set of layers) to be opened is always desirable. The common practice performed during drilling and completion activities of a production well is through the use of well testing and fluid sampling. From the test, fluid dynamic data such as total liquid rate, water cut, and gas cut are produced. A similar set of data is also required for more mature fields for the purpose of monitoring through the running of routine production and/or swab tests.Although the tests, especially flow tests during drilling and completion, are always regarded as the only source of proof about productive layer(s) production potential, an alternative means that can be used to provide estimates is always desired. The main reason is that flow tests are costly so that only layer(s) considered as the most potential are to be assigned for testing. Layer(s) that are considered less potential are left untested, eventhough in some cases they are also set on production during the well's production phase.The idea of establishing a method that can provide illustration over production potentials of all layer(s) always exists. Certainly, there are approaches to serve the purpose such as productivity index (PI) analogy and petrophysical through fractional flow measurement in a core laboratory. However, those approaches are often considered inadequate in accommodating various factors that may influence production potential.To materialize the idea stated above, the pattern recognition approach was taken. This approach was taken in order to model the relationships between various fac- tors in wellbore and production potential without being trapped by the certain complexity that occurs in any mathematical expressions trying to explain the relationships. For the purpose, fuzzy logie (a branch in ArtificialIntelligence) has been used. The choice is actually based on its ability to accommodate both numeric and non-numeric data. Some non-numeric data such as lithology and pore system also have some degrees of influence on production potential. With a tool that enables us to have production potential estimates of reservoir layers, from which layers with the most promising potential are taken to undergo flow tests. Furthermore, as flow test data has been acquired and used as feedback and calibration by the fuzzy model, production potential of layer(s) with less promising or ambiguous prospect can also be predicted.
The Influence Of Ph And Concentration Of Phosphonate Inhibitor - Tests On Change Of Barium Sulfate Scale Morphology By Using Scanning Electron Microscope Tjuwati Makmur
Scientific Contributions Oil and Gas Vol 27 No 2 (2004)
Publisher : Testing Center for Oil and Gas LEMIGAS

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.29017/SCOG.27.2.873

Abstract

Water injection is often used to keep maintaining reservoir pressure. Injected water (high in sulphate) mixes with formation water (high in barium) leading to the deposition of barium sulfate scale in the near wellbore, reservoir, production tubulars and topside equipment. Barium sulfate scale is unique scale deposit and the least soluble of the scales. The deposition of oil field scale is a potentially damaging problem which reduces fluid flow resulting in a decline in oil production. The best approach to solving the problems of scale formation is to prevent or inhibit deposition and this is more effective than scale removal. The use of scale inhibitor can be effective method for preventing scalealthough their effectiveness is controlled by experimental conditions. Therefore, it is very important to know factors that influence barium sulfate scale. The maintopic of this paper is “The Influence of pH and Concentration of Inhibitor Solution - Tests on Change of Barium Sulfate Scale Morphology by Using Scanning Electron Microscope”. Hopefully, the results of laboratory test presented this paper give useful and valuable information not only for LEMIGAS, but also for oil industry, chemical manufacturers and universities, then other institutions.
Prediction Of Two-Phase Relative Permeability In Porqus Media Based On Network Modeling Of Lattice Gas Automata Dedy Kristanto; Mariyamni Awang
Scientific Contributions Oil and Gas Vol 27 No 1 (2004)
Publisher : Testing Center for Oil and Gas LEMIGAS

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.29017/SCOG.27.1.874

Abstract

The displacement of one fluid by another is controlled by the geometry of the pore space. The relative hydrodynamic conductance of each fluid at a given saturation is the relative permeability, while the pressure difference between the phases is the capillary pressure. These two functions determine the macroscopic fluid flow behavior in hydrocarbon reservoir over the scale of centimeters to kilometers.At the pore seale fluids reside in intergranular space of typical sedimentary rocks. The rock type and fluid properties are likely to change drastically through the reservoir, the only sample of rock come from drilling wells, which represents a tiny fraction of the total volume in a reservoir. Furthermore, relative permeability measurements on these samples are difficult and time consuming. To quantify and control uncertainty in recovery estimations, it is necessary to have some theoretical understanding of transport properties. Such understanding would enable us to predict the sensitivity of relative permeability to geological factors such rosity, and the nature of the fluids. This work is a pre- liminary step in this direction. A more important result from this work is that we are now able to quantify the change in the relative permeability to those geological factors.In this paper a pore structure and displacements mechanisms to model two-phase flow in porous media were constructed using lattice gas automata. The void space of the media is represented as a network of large spaces (pores) connected by narrower throats. The aggregation of cell pore volumes is used to calculate the porosity of the network and the fluid saturation when different cells are occupied by different fluids. By judicious choices for the distribution of pore and throat sizes of the network it is possible to predict relative permeability. For predicting the absolute and relative permeability, it is assumed that the viscous pressure drops occur across the throats.
An Intelligent Approach For Obtaining True Resistivity (𝑅𝑇) From Rock Acoustic Data : A Laboratory Verification Bambang Widarsono; Fakhriyadi Saptono; Heru Atmoko
Scientific Contributions Oil and Gas Vol 26 No 1 (2003)
Publisher : Testing Center for Oil and Gas LEMIGAS

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.29017/SCOG.26.1.875

Abstract

Rock true resistivity (Rt) is known as more sensitive than compressional-wave velocity (Vp), the principal output of a seismic survey, to variation in water saturation. Therefore, it would be of a great value if there were a way to predict resistivity distribution from seismic signals. This study is essentially an effort to see the possibility of predicting Rt from Vp through a pattern recognition approach. For the purpose, a series of laboratory tests were performed on some Central Sumatran clay-free sandstone samples of various porosity values and at various water saturation levels. For studying the pattern of relationship, artificial neural networks (ANNs) were applied. From the ‘training’ (i.e.pattern recognition) activity performed using the ANNs, it has been show between Vp and Rt in the following ‘blind test’, it has also been shown that the trained relationship can be used to estimate Rt reliably using other data as input. Comparisons between estimated and observed Rt data have indicated good agreement implying the success of the approach taken in the study. This has laid the foundation and justification for further application of the approach on seismic and well-log data.
Dst Data Evaluation In Practice Herlan Adim
Scientific Contributions Oil and Gas Vol 25 No 3 (2002)
Publisher : Testing Center for Oil and Gas LEMIGAS

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.29017/SCOG.25.3.877

Abstract

Originally Drill Stem Test (DST), as an evaluation tool, was only an indicator of type of fluid production. Interest in the DST as a modern evaluation tool was revived when certain theoretical equations were proven as a means of calculating values for important formation parameters. This paper is an example, the basic interpretation method, that will prepare the geologist and engineer for more sophisticated approaches that are sure to come, It is proposed of this paper to show how DST data might be Ned to make certain reservoir parameter de- terminations, in field works.
Palynology Of The Lower Kalicapung Formation Tlogosari, Central Java Eko Budi Lelono
Scientific Contributions Oil and Gas Vol 25 No 2 (2002)
Publisher : Testing Center for Oil and Gas LEMIGAS

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.29017/SCOG.25.2.878

Abstract

The palynological investigation focuses on the transition sediment of the Lower Kalipucang Formation which overlies the non-marine lava of the Gabon Formation. Both formations are firmly separated by the unconformity which is indicated by the occurrence of basal conglomerate. The Lower Kalipucang Formation outcrops in a small village called Tlogosari, Central Java. Lithologically, it is characterised by the occurrence of basal conglomerate with the intercalation of thin lignites. This lithology is overlain by 2 meter thick of claystone containing lignite strings and some igneous fragments. The intercalation of thin sandstones, conglomerate and lignites are found within claystone lithology. Four samples from the Lower Kalipucang Formation were selected for laboratory processing. Only two samples collected from the upper part of this formation yield rich palynomorphs. The palynomorph assemblage shows the occurrence of brackish and fresh water floras. Based on the appearance of pollen Florschuetzia meridionalis and F. trilobata, it is predicted that the age of the Lower Kalipucang Formation is Middle Miocene. The high abundance of mangrove taxa (especially in sample number LKP-4) such as Avicenia type, Zonocostites ramonae and Camptostemon indicates a well development of mangrove environment. This assumption is supported by well preservation of large mollusc with excellent ornamentation. This ornamentation must have developed in the environment with low energy such as mangrove.

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