Article Per Year (5 Year)
p-Index From 2021 - 2026
1.619
P-Index
This Author published in this journals
All Journal Indonesian Journal of Electrical Engineering and Computer Science Indonesian Journal of International Law Scientific Contributions Oil and Gas LEMBARAN PUBLIKASI MINYAK DAN GAS BUMI (LPMGB)
Bambang Widarsono
Unknown Affiliation
Chemical Engineering, Chemistry & Bioengineering Energy Law, Crime, Criminology & Criminal Justice Social Sciences

Published : 31 Documents Claim Missing Document
Claim Missing Document
Check
Articles

Found 31 Documents
Search

 1   2   3   4 
Irreducible Water Saturation And Its Governing Factors: Characteristics Of Some Sandstones In Western Indonesia Bambang Widarsono
Scientific Contributions Oil and Gas Vol 34 No 1 (2011)
Publisher : Testing Center for Oil and Gas LEMIGAS

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.29017/SCOG.34.1.788

Abstract

Irreducible water saturation (Swirr) plays a very significant role in the estimation of hydrocarbon in place and reserves. Inaccurate Swirr and lack of knowledge for judging its accuracy may result in erroneous and misleading reserve estimates along with its consequences. This study is basically aimed at understanding of Swirr characteristics of reservoir sandstones in some fields in western Indonesia. For the study, data obtained from 1,334 core samples – taken from 78 fields in 10 sedimentary basins – is used. Observations and investigations are made in sedimentary basin, field, and formation scales. The main finding is that rock wettability plays a very significant factor in determining Swirr characteristics, in a manner more than what rock pore types and configuration do. Its variation – be it contrasting or difference in strength – influences the Swirr characteristics in its relation to rock permeability. It is also found that geological similarity and geographical proximity do not have effects on Swirr characteristics unless they directly affect the rock’s overall wettability. This occurs not only at higher scale of sedimentary basin but also at lower levels of field and rock formations. The study also produces permeability - Swirr correlations for both sedimentary basins and rock formations levels. The overall results of this study is an understanding that gross simplification in assuming reservoir general wettability has to avoided in order to prevent erroneous picture over a field’s most representative Swirr characteristics.
Rock Wettability Characteristics Of Some Indonesian Limestones Case Study: Baturaja Formation Bambang Widarsono
Scientific Contributions Oil and Gas Vol 34 No 2 (2011)
Publisher : Testing Center for Oil and Gas LEMIGAS

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.29017/SCOG.34.2.796

Abstract

Rock wettability plays a very important role in affecting various rock physical properties such as relative permeability and capillary pressure. Common practice at present is that carbonate rocks are assumed to be preferentially oil wet in nature. This assumption may prove fatal since the need of true knowledge over the real wettability for one’s carbonate reservoir is often neglected, and wettability aspect in reservoir modeling is in turn based on assumption. To prove over reliability of the assumption a study is carried out using information from 350 core samples taken from Baturaja Formation. The choice for the Baturaja limestone is basically based on the fact that it is a mature productive rock formation and its extensive spread into three of the most productive sedimentary basin in Indonesia, Northwest Java Basin, South Sumatra Basin, and Sunda Basin. The study proves that the assumption of the generally oil wet limestone does not apply for Baturaja limestone. The Baturaja limestone tend to exhibit, quantitatively, equality in their tendency towards oil wettability and water wettability and leave some proportion to neutral or mix wettability as well. However, when a more detailed comparison is made results show that qualitatively the limestone are indeed more inclined to oil wettability than water wettability even though this finding is insufficient to support a conclusion that the Baturaja limestone are specifically oil wet. Other finding from comparison with past studies also shows that limestone may behave in the way sandstones do. Both limestone and sandstones may vary in the same way and no assumption over their preferential wettability is justified without direct measurements. Wettability alteration as the result of hot core cleaning following the widely accepted standard procedure is also strongly indicated. It is therefore concluded that the practice has to be abandoned for a better and reliable laboratory testing results.
The Importance Of Litho-Facies Distinction In Determining The Most Representative Cementation Factors For Well-Log Evaluation : An Old Issue Persistently Neglected Bambang Widarsono
Scientific Contributions Oil and Gas Vol 34 No 2 (2011)
Publisher : Testing Center for Oil and Gas LEMIGAS

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.29017/SCOG.34.2.800

Abstract

Cementation factor is a parameter always required in any conventional open-hole log analysis leading to determination of water saturation. Considering the central of water saturation in the estimation of hydrocarbon in place and reserves, any error in the use of the parameter may prove fatal. A common practice in the oil industry is that acquisition of laboratory-derived cementation factor has never been given a proper attention. It occurs very often that too few samples – hardly represent the rocks of reservoir of concern – are assigned for laboratory test. The practical use of the parameter in the log analysis also often draw question, in which un-representative cementation factor is arbitrarily used due to lack of the data. The effect of this practice has long been known but is often neglected – with all of its consequences – up to present day. This study tries to revive the awareness through presenting a fact that cementation factor may vary due to differences in litho-facies characteristics. Formation resistivity factor data from forty-seven limestone coreplug samples were taken from a West Java (WJ) field. Visual description over the samples has shown that they belong to several litho-facies types. Results of the study have mainly proved that different litho-facies type may have significantly different cementation factors. An averaging effect is also obvious when data from all samples are processed collectively. The effect of improper use of cementation factor is shown through the application of three water saturation models through which erroneous water saturation estimates are produced. The finding of the study is again hoped to reinforce the awareness of the use of proper and representative cementation factor
Improving Accuracy Of Fluid Contact Determination Through The Use Of An Auxiliary Transform Method Bambang Widarsono
Scientific Contributions Oil and Gas Vol 34 No 3 (2011)
Publisher : Testing Center for Oil and Gas LEMIGAS

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.29017/SCOG.34.3.802

Abstract

Fluid contact(s) in reservoir sets the lower limit above which an accumulation of hydrocarbon (i.e. oil or gas) has the maximum level of mobility under a specific circumstance. This mobile hydrocarbon determines the reservoir’s production feasibility. In this light, an accurate knowledge over position of fluid contact contributes to accuracy in the estimation of initial hydrocarbon in place and its corresponding reserves. Determination of fluid contact in reservoir may utilize any available sources of information but well pressure survey data is usually regarded as the primary source of information. Despite the importance, the data is sometimes not in ideal condition usually marked by absence in clear change of pressure gradient and/or data scatter for various reasons. The use of Hough transform – as introduced by Kang and Xue (2009) – for supporting fluid contact detection can solve the problem. In this study, the method that is usually used for, among others, recognizing regular shapes in images has been successfully applied for fluid contact detection. The study uses three sets of data with different level of difficulty, and the technique proves to work well for the all cases. The study also shows that the Hough transform can be used reliably in a simple way without employing the full weight of it.
Differential Strain Analysis: An Investigation Over Its Feasibility For Determining Coal’s Cleat Orientation Bambang Widarsono
Scientific Contributions Oil and Gas Vol 33 No 2 (2010)
Publisher : Testing Center for Oil and Gas LEMIGAS

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.29017/SCOG.33.2.813

Abstract

Gas production from coal bed methane (CBM) has been rising as supplement to conventional gas reservoirs. Effective CBM production is much determined by well placements with regards to orientation of the coal reservoir’s face cleat. This is true since this cleat type provides the main path of fluid migration from storage to wellbore. It is therefore imperative to understand and determine the general orientation of the cleats of concern. This information is usually obtained from visual description on core samples, and whenever available from analogy to outcrop data. This is considered as insufficient and a means for studying core sample’s interior is required in order to ensure consistency between external and internal appearances. This paper presents an investigative study over the possibility of differential strain analysis (DSA) technique to serve the purpose. The technique is normally used for measuring subsurface in situ stress field, and through the use of a similar basic concept it is proposed to be used for determining orientation of face cleats in coal samples. The study includes utilization of DSA data obtained from measurements on samples taken from great depths. Review and re-working over the data has shown that the technique can well indicate the orientation of face cleats. A general orientation over all tested samples is also indicated with reasonable degree of reliability. This leads into conclusion that the DSA technique can be well used to indicate cleat orientation and therefore help in better characterizing coal.
An Investigation Over Rock Wettability And Its Alteration On Some Indonesian Sandstones Bambang Widarsono
Scientific Contributions Oil and Gas Vol 33 No 3 (2010)
Publisher : Testing Center for Oil and Gas LEMIGAS

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.29017/SCOG.33.3.820

Abstract

Wettability is a reservoir rock property that is not easy to measure and quantify but has a crucial effect on other rock properties such as relative permeability, capillary pressure, and electrical properties. Problem that may occur with regard to this matter is that those properties are often measured on already cleansed core samples as part of the standard procedure. Having undergone the normally utilized heated cleansing process alteration in the rock’s original wettability was often reported. Under such condition, unrepresentative wettability certainly leads to unrepresentative measured data with all of consequences. This article presents a study that uses 363 sandstone samples retrieved from 28 oil and gas fields in Indonesia. The study consists of two stages of analysis. First analysis is performed on data obtained from three wettability tests results while the second one is made with using water-oil relative permeability data, that is usually measured on cleansed core samples. Original wettability data shows that the sandstones varry in wettability from water-wet to oil-wet (48.2% and 30.2% of total samples, respectively). Comparison between data of the two analyses shows that original wettability tends to degrade in strength after cleaning down to neutral wettability, among which neutral wettability appears to be the largest in number (49.1% of total sample). Results also show that weak wettability tends to endure more than stronger ones. The overall results have demonstrated the need for caution in core handling and for measures that can minimize the risk.
Integrating Petrography With Core-Log-Well Test Data For Low Permeability Sandstone Reservoir Characterization: Preliminary Recommendation For Production Optimization Junita Trivianty Musu; Hadi Prasetyo; Bambang Widarsono
Scientific Contributions Oil and Gas Vol 33 No 3 (2010)
Publisher : Testing Center for Oil and Gas LEMIGAS

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.29017/SCOG.33.3.823

Abstract

Integrating petrographic core information into combined core petrophysics, log, and well test data for understanding facies and environmental deposition in rock characterization has proved itself useful to improving quality and reliability of the required conclusions. This integrated approach has specifically shown its use in the cases of complex reservoirs such ones characterized as low-permeability sandstone reservoirs. It is in this spirit that this paper demonstrates how this virtually cost efficient analysis provides preliminary recommendations for the exploitation of such reservoirs. As case study, two types of producing reservoirs (Bekasap, Bangko, Pematang, and Tanjung Formations) have been taken in 2009. The first type is strongly controlled by depositional environment. It is found in the upper part of Bekasap and Bangko formations (1900 - 2300 ft-ss), deposited in estuarine system, and made of very fine to fine grained sand with low to moderate bioturbation. This mostly feldspathic and lithic greywackes have permeability of up to 200 mD. The second type is strongly dominated by diagenesis process and is mainly found in the Upper Pematang and Tanjung Formations (6200 - 7400 ft-ss). This reservoir type is characterized by its coarse-grained and conglomeratic sandstones resulted from fan- elta and braided channel depositional system. Diagenetic events such as compaction, recrystallization of matrix into microcrystalline clay minerals, precipitation of authigenic minerals in pore system are also well identified from the performed petrographic analysis. This is dominated by sublitharenite and litharenite sandstones exhibit horizontal permeability of up to several dozens mD. The two producing reservoir types have undergone carefully planned exploitation and stimulation operations, and the horizontal drilling and fracturing
Estimation Of Water Saturation In Carbonate Reservoirs Without Resistivity Log Data. Part Ii: Formulation Of A New Model Bambang Widarsono; Heru Atmoko; Ridwan Ridwan; Kosasih Kosasih
Scientific Contributions Oil and Gas Vol 32 No 1 (2009)
Publisher : Testing Center for Oil and Gas LEMIGAS

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.29017/SCOG.32.1.827

Abstract

This paper is the second part of the two-part report on study for establishing alternative models that are valid for Indonesian carbonate reservoirs. In this second part formulation of the new models is presented. For the study, 407 plug samples taken from various limestone reservoirs in Indonesia were used. Following Lucia’s procedure the samples were classified, grouped, averaged, and their capillary pressure data was formulated to form water saturation models that are essentially functions of porosity and height above free water level. Validity test on the models are performed on two wells in West Java with very encouraging results. With using the Archie model as reference, justified using well test data, the new models prove themselves reliable while the original Lucia models provide far too optimistic estimates. The model validity check shows tha the models are valid for at least Class 1 and Class 2 rocks in accordance with Lucia classification. Study on Class 3 rock is needed in the future
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

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.29017/SCOG.32.2.839

Abstract

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
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).
Co-Authors Anda Lucia Andi Ruswandi Arie Rahmadi Atmoko, Heru Atyanto D Atmoko Aziz M Lubad Bambang A Widjayanto Caryana, Yusep K Danang Sismartono Desi Yensusminar Diana Dwiyanarti Djoko Sunarjanto Endras Pribadi Fakhriyadi Saptono Hadimuljono, Jonathan Setyoko Hazman Hazman Hazman Hazman, Hazman Herru L Setiawan Herru Lastiadi Herru Lastiadi Setiawan Heru Atmoko Heru Atnioko Heru Atnwko Heru Riyanto Himawan Sutanto Himawan Sutanto, Himawan Humbang Purba Humbang, Purba Ida Ayu Putu Sri Widnyani Jonathan Setyoko Hadimuljono Julikah Julikah Julikah Julikah, Julikah Junita Trivianty Junita Trivianty Musu Kosasih Kosasih KOSASIH KOSASIH, KOSASIH Kosasih Sartadiredja Lucia, Anda Maizar Rahman Mendrofa, Merkurius F Merkurius F Mendrofa Merkurius. F. Mendrofa Mohamad Romli Musu, Junita T. Musu, Junita Trivianty Nurkamelia Nurkamelia, Nurkamelia Ongki Ari Prayoga Panca Wahyudi Pasarai, Usman Patrick M Wong Prayoga, Ongki Ari Pribadi, Endras Rahman, Maizar Ridwan Ridwan Ridwan Ridwan, Ridwan Romli, Mohamad Rosidelly Rosidelly Rosidelly Rosidelly, Rosidelly Rudi Suhartono Ruswandi, Andi Saptono, Fakhriyadi Sartadiredja, Kosasih Septi Anggraeni Setiawan, Herru Lastiadi Sugihardjo Sugihardjo Sugihardjo Suhartono, Rudi Sukarno, Panca W. Suliantara Suliantara Suliantara Suliantara, Suliantara Sunarjanto, Djoko Sunting Kepies Suprajitno Munadi Suprajitno Munadi Tri Muji Susantoro Tri Muji Susantoro, Tri Muji Tunggal Tunggal Tunggal Tunggal, Tunggal Usman Usman Pasarai Usman Pasarai Usman Usman Wanda Ali Akbar Widjayanto, Bambang A Wong, Patrick M Yensusminar, Desi Yohanes, Yohanes D. Wangge Yusep K Caryana