Scientific Contributions Oil and Gas
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.
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Pollen Record Of Early/ Middle Miocene Boundary In The South Sumatra Basin
Eko Budi Lelono
Scientific Contributions Oil and Gas Vol 32 No 2 (2009)
Publisher : Testing Center for Oil and Gas LEMIGAS
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DOI: 10.29017/SCOG.32.2.836
Early to Middle Miocene sediment obtained from three wells drilled in South Sumatera area has been evaluated for its micropaleontological content including foraminifera, calcareous nannoplankton and palynomorph. The boundary of Early/ Middle Miocene is clearly represented by zone N8/ N9 boundary based on foraminiferal analysis and zone NN4/ NN5 boundary on the basis of calcareous nannoplankton analysis. The rich assemblage of foraminifera and calcareous nannoplankton indicates the occurrence of marine sediment within the well sections. In addition, environmental markers of benthonic foraminifera suggest the occurrence of inner to middle neritic along the studied sections. Palynological analysis however, proves the high occurrence of pollen and spore along the marine successions situated in Early/ Middle Miocene boundary which is the first time to yield a good quality of palynological record. The Early/ Middle Miocene boundary is marked by low sea level in global sea level curve as indicated by significant decrease of foraminifera and calcareous nannoplankton. In addition, palynological record reflects climatic changes over N8/ N9 sediment marking Early/ Middle Miocene boundary with the declines of pollen assemblage suggesting seasonal/ dry climate condition. N8 sediment shows high abundance and diversity of palynomorphs including those of wet climate markers. Palynological assemblage drops gradually approaching foram zone N9/ N8 boundary, whilst seasonal climate indicators increase. On the other hand, palynological record recovers its assemblage over N9 sediment.
A New Procedure For Reservoir Fluid Characterization With Equation Of State (EOS)
Ego Syahrial
Scientific Contributions Oil and Gas Vol 32 No 2 (2009)
Publisher : Testing Center for Oil and Gas LEMIGAS
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DOI: 10.29017/SCOG.32.2.837
A new procedure for reservoir fluid characterization through equation of state (EOS) is proposed. It is applied in a selecting the most appropriate fluid composition for the purpose of reservoir fluid characterization. A Hoffman-Crump-Hocott plot is used to determine whether or not the streams are genuine equilibrium fluids. With the aid of phase diagram and saturation pressure from RFT, the most appropriate fluid sample was chosen for fitting an equation of state to experimental data through regression. Based on data analysis and quality control of all PVT data suggested that fluid from UP-1 DST-3 is the best representative of XYZ field. The PR3-EOS and LBC correlation are applied to the UP-1 DST-3 data sets under conditions of predictions and regression. Agreement between laboratory data and regressed EOS results is generally good to excellent. The results show that that regression on critical properties of components is sufficient for good data matches. In this work, a good agreement with experimental data was obtained with grouping (lumping) 15 to 7 components.
Spectral Decomposition Made Simple
Suprajitno Munadi;
Humbang Purba
Scientific Contributions Oil and Gas Vol 32 No 2 (2009)
Publisher : Testing Center for Oil and Gas LEMIGAS
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DOI: 10.29017/SCOG.32.2.838
Spectral decomposition enables the resolution of seismic data to be improved significantly yielding a new possibility to map thin layers such channel sands and any other stratigraphic features. It has also been used in reservoir characterization. There are three methods for implementing spectral decomposition i.e., The Short Time Fourier Transform, the Continuous Wavelet Transform and the Matching Pursuit Decomposition. Among three of them, the Matching Pursuit Decomposition seems to be the most sophisticated one. It gives the best resolution among them. A simple and logical approach for explaining the spectral decomposition methods together with real data examples are presented in this paper by avoiding complex mathematical formulation.
Establishment Of More Reliable Equations For Estimation Of Coalbed Methane Proximate Analysis Data
Bambang Widarsono;
Kosasih Sartadiredja;
Bambang A Widjayanto
Scientific Contributions Oil and Gas Vol 32 No 2 (2009)
Publisher : Testing Center for Oil and Gas LEMIGAS
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DOI: 10.29017/SCOG.32.2.839
Coal bed methane (CBM) data such as ash contents, moisture contents, volatile matters, and fixed carbon – commonly obtained from log analysis - are direct input to calculation of gas accumulation in CBM reservoirs. However, recent studies on some coal samples taken from Rambutan field CBM pilot project have shown that the commonly used log analysis equations are simply inapplicable for the field’s coal samples. Calculation results tend to give far different magnitudes when compared to laboratory results. After a series of re-evaluations and re-measurements on the laboratory results it was convinced that the problem does not lie with the laboratory results but with these ‘conventional’ equations. Therefore modification efforts are spent to find better equations. Comparisons between measured data (coal samples taken from two coal seams in the field) and calculated data show that only equation for ash contents gives accurate results. The other proximate analysis output data - i.e. moisture contents, volatile matter, and fixed carbon – is at considerable odd with their corresponding calculated data. Modification upon the original empirical models is then carried out. The following modifications on the equations have produced analogous but different empirical equations to the original equations. These equations certainly work more reliably for the field’s coals, and these better results underline that future log analyses in the field have to use the modified equations
Determination Of Asphaltene And C, H, N, O, S Contents In Crude Oil From X-Oilfield In South Sumatra
Tjuwati Makmur
Scientific Contributions Oil and Gas Vol 32 No 2 (2009)
Publisher : Testing Center for Oil and Gas LEMIGAS
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DOI: 10.29017/SCOG.32.2.840
All analyzed crude oil samples contain firstly, the carbon contents in a range of 75.2830 % wt – 83.5739 % wt. Secondly, asphalthene with in a range of 0.6930 % wt – 1.8260 % wt and it can deposit in the formation and block the pore throats, which may reduce the permeability significantly. Thirdly, the hydrogen contents in a range of 9.1948 % wt –11.2339 % wt and it is impurities crude oil indicator. Fourthly, the crude oil samples have zero % wt nitrogen contents and don’t result in corrosive properties. However, the existence of the oxygen contents (in a range of 5.1634 % wt – 14.0560 % wt) and the sulfur contents (in a range of 0.1334 % wt – 0.2533 % wt) in the crude oil samples may cause corrosion problem.
Carbon Bed Interflow Performance Prediction Using Variable Hypothetic Pressure Wave Cycles Model
Yusep K Caryana
Scientific Contributions Oil and Gas Vol 32 No 2 (2009)
Publisher : Testing Center for Oil and Gas LEMIGAS
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DOI: 10.29017/SCOG.32.2.841
The nature of low productivity of CBM well experiences represent low interflow performace over matrix and fractures in coal bed. Therefore, to increase CBM well production rate, it is necessary to improve the interflow performace. An approach to improve the interflow performance is to find out the possibility of increasing gas flowrate in carbon bed taken into account factors dominantly effect on the performance. For this purposes, Variable Pressure Wave Cycles Hypothetical Model has been developed based on Pressure-Swing adsorption - desorption (PSA) technique commonly applies in natural gas separation using carbon active bed. Preliminary simulation of the model has been carried out using data related to carbon bed taken from previous studies. Variables in the simulation are kinetic constant and hypothetic pressure waves generated which is required to increase gas flow rate in the bed. The simulation results demonstrate the possibility of interflow performance improvement in carbon bed. However, this improvement is asymptotically limited to maximum amount of gas desorbed from carbon bed as well as Langmuir Isotherm pattern application for gas desorption from coal. Moreover, the simulation of the model shows the sensitivity of gas interflow performance to hypothetical pressure waves generated and kinetics controlling adsorption/desorption mechanism and mass transport in carbon bed.
The Influence Of Wet And Dry Seasons Conditions On Chemical Compositions, Properties And Total Suspended Solids Of Different Water Source And Type In Riau-Oil Fields
Tjuwati Makmur;
Nuraini Nuraini
Scientific Contributions Oil and Gas Vol 32 No 2 (2009)
Publisher : Testing Center for Oil and Gas LEMIGAS
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DOI: 10.29017/SCOG.32.2.842
Change of wet and dry seasons conditions have major impact, the results of chemical compositions concentration determination for RRV, RST, ORK, KWT, KWL and PRD water samples (sampling in dry seasons) are higher than in wet seasons. All of the analyzed water samples don’t results in the occurrence of calcium sulfate. Only PRD water has potential to form calcium carbonate scale, because pH value in a range of 7.85 – 8.10 (pH >7). The RRV, RST, ORK, KWT, KWL and PRD (sampling in wet and dry seasons) have poor injection water quality, because the concentrations of total suspended solids (TSS) in the analyzed water samples are higher than 8 ppm.
An Environmentally Friendly Wbm System Can Prevent Hard Brittle Shale Instability
Chunyao Peng;
Wenqiang Feng;
Xiaohu Luo;
Shujiao Li;
Chen Riji
Scientific Contributions Oil and Gas Vol 32 No 2 (2009)
Publisher : Testing Center for Oil and Gas LEMIGAS
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DOI: 10.29017/SCOG.32.2.843
In the Weizhou Southwest oilfields, drilling delays and suspension of wells prior to reaching the targets due to wellbore instability had occurred frequently. The hard brittle shale played a problematic role. Conventional water-based drilling fluids didn’t conquer the problematic formation due to intrinsically performance deficiencies. While Oil based drilling fluids are routinely preferred in the more technically demanding applications, they are cause for increasing concern due to offshore environmental restrictions and expensive disposal costs. An environmentally acceptable water-based drilling fluid was developed to challenge the problematic formation based on the combination of methylglucoside-silicate concept. It stabilized the reactive shale by the same mechanism as did oil-based drilling fluid in preventing shale hydration, pore pressure increase and weakening of shale by effectively developing sufficient osmotic force to offset hydraulic and chemical forces acting to cause filtration flux into the hard brittle shale. A field trial was initiated on the CNOOC 931 platform in Weizhou oilfield. The data from the pilot well showed that the novel drilling fluid exhibited excellent inhibition and lubricity which approached or even exceeded oil-based fluids.
The New Approach For Zonal Subdivision Of Pliocene - Pleistocene Nannoplankton Biostratigraphy In Waipoga-Waropen Basin, Papua
Panuju Panuju
Scientific Contributions Oil and Gas Vol 32 No 2 (2009)
Publisher : Testing Center for Oil and Gas LEMIGAS
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DOI: 10.29017/SCOG.32.2.844
Waipoga-Waropen Basin is placed in northern part of Papua on the island of New Guinea. The gas discoveries had been made since 1958 in this basin, however, no economic value of reserves lead to the not producing basin state until this time. The main problem in Waipoga-Waropen Basin is great thickness of Pleistocene sedimentary layers (until 7500m) as product of turbidite system (Wold & Barret, 2000). This makes difficulty in well section correlation based on the conventional biostratigraphy since individual layers within that section is being small part of biozone. Many reworked nannoplankton as implication of turbidite deposit are also being complicated aspect in biostratigraphic analysis. The Pleistocene ranges from 1.806 m.a. to 11.550 k.a. It was the most recent episode of global cooling or ice age took place. In nannoplankton biostratigraphy, this age is characterized by the extinction of Discoaster brouweri (Discoaster group) at the bottom and the first occurrence of Emiliania huxleyi at the top. The quatitative nannoplankton investigation of “T†well has been done, and there is evident that its sedimentary section gives the excellent nannoplankton assemblages to subdivide Pleistocene age sediments of Waipoga-Waropen Basin (Zone NN19) into 9 subzones. Biomarkers from the bottom to the top consist of: LO of Discoaster brouweri, FO of Gephyrocapsa caribbeanica, FO of Gephyrocapsa oceanica, LO of Cacidiscus macintyre , LO of Helicosphaera sellii, FO of Reticulofenestra asanoi, FO of Gephyrocapsa parallela, LO of Reticulofenestra asanoi, FO of Helicosphaera inversa and LO of Pseudoemiliania lacunosa. The sediments belong to zone NN 20 that placed in the uppermost part of Pleistocene were not analysed.
The Occurrence Of Corrosion Problem In Oil Production Equipment Caused By Sulfate Reducing Bacteria And Dissolved Oxygen
Nuraini Nuraini;
Febrianto Febrianto
Scientific Contributions Oil and Gas Vol 32 No 2 (2009)
Publisher : Testing Center for Oil and Gas LEMIGAS
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DOI: 10.29017/SCOG.32.2.845
One of most problems occur in oil production equipments is corrosion that is caused by some factors, such as the existence of sulfate reducing bacteria and dissolved oxygen in injection water. Based on the results of laboratory, A–GS and R–GS contain 0.90 ppm and 1.19 ppm dissolved oxygen and have potential to form corrosion problem, except D–GS with 0 ppm dissolved oxygen and no corrosion problem. After SRB tests, A–GS tube appearance colour is not black, because SRB is not found in the A–GS injection water. Whereas, R–GS and D–GS contain SRB with sulfate reducers > 100,000, therefore R–GS and D–GS tubes appearance colour are completely black