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Avo Inversion Using Levenberg-Marquardt Optimization Technique Suprajitno Munadi; Humbang Purba
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.33.2.812

Abstract

AVO is not only well known as gas indicator over the last two decades but also more importantly, AVO provides us with a means for extracting petrophysical parameters from seismic data. Using AVO anomaly one can derive important petrophysical parameters such as Poisson’s ratio and S-wave velocity. By knowing S-wave velocity nearly all other petrophysical parameters can be calculated. An effective procedure for inverting AVO anomaly is presented in this paper. It avoids inefficient trial and error steps during the matching process between AVO anomaly and calculated AVO. This method uses Levenberg-Marquardt optimization technique.
Seismic Versus Sonic Revisited Suprajitno Munadi
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.32.1.826

Abstract

The sonic log enables all features along the depth scale can be correlated with all features in the ime scale as found in the seismic section. However, this sonic log must beThe sonic log enables all atures along the depth scale can be correlated with all features in the time scale as found in the seismic section. However, this sonic log must be corrected to the time-depth curve obtained from the check shot survey. The problem arises when some zones around the borehole such as the invaded zones or the flushed zones exhibit dispersive properties. This dispersive properties causes discrepancies between integrated sonic transit time and the time-depth curve. As a result, the synthetic seismogram generated from the sonic log will not match with the corresponding seismic section. To solve this problem, a practical method for correcting the discrepancies is presented in this paper. Although the method is inspired by paper published in the seventies, but the way to approach the problem is different. This problem looks simple, but its effect on mapping top and bottom of the reservoir is important. An example of implementation from the real field is also given. corrected to the time-depth curve obtained from the check shot survey. The problem arises when some zones around the borehole such as the invaded zones or the flushed zones exhibit dispersive properties. This dispersive properties causes discrepancies between integrated sonic transit time and the time-depth curve. As a result, the synthetic seismogram generated from the sonic log will not match with the corresponding seismic section. To solve this problem, a practical method for correcting the discrepancies is presented in this paper. Although the method is inspired by paper published in the seventies, but the way to approach the problem is different. This problem looks simple, but its effect on mapping top and bottom of the reservoir is important. An example of implementation from the real field is also given.
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

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.29017/SCOG.32.2.838

Abstract

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.
Application of Artificial Neural Network for Assisting Seismic-Based Reservoir Characterization Bambang Widarsono; Fakhriyadi Saptono; Patrick M Wong; Suprajitno Munadi
Scientific Contributions Oil and Gas Vol 25 No 1 (2002)
Publisher : Testing Center for Oil and Gas LEMIGAS

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.29017/SCOG.25.1.879

Abstract

 Reservoir rock physical properties, such as porosity and water saturation, always play prominent roles in the development of oil and gas fields. Accurate information regarding their distribution is always desired. For this new approach that uses a purpose, a combination of intelligent computing (artificial neural network or ANN) and rock physics, with a full utilization of core data, well logs and seismic-derived attributes, is proposed. The method is basically an effort to link the required rock physical properties to seismic- derived attributes through the use of rock physics theories. The ANN itself is used to fill the gaps of data array required by the proposed method through its capacity for pattern recognition. The proposed method is applied to a limestone reservoir in East Java. Validation is carried out by comparing the results to the observed data at well locations as well as by geological justification. The application has shown a new potential for supporting reservoir modeling and field development.
Fast Hilbert Transform Suprajitno Munadi
Scientific Contributions Oil and Gas Vol 11 No 1 (1988)
Publisher : Testing Center for Oil and Gas LEMIGAS

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.29017/SCOG.11.1.894

Abstract

The use of Hilbert Transform is becoming more and more Important for analysis and processing of geophysical data. However, the direct mathematical formulation in the form of contour integration is not easy to pro. A specific formulation which relates the Hilbert transform and the Fourier transform has been established for developing a computer Programme. This relationship enables us to execute the Hilbert Transformation in a very quick manner using the well known Fast Fourier transform algorithm.The application of this method for generating quadrature seismic trace and recovering minimum phase specimum from the magnitude demonstrates the effectiveness of the programme. The conversion of non-minimum phase seismic wavelet whichas similar spectral magnitude can be done using the hilbert transform.
A New Type Of Digital Band - Pass Filter Suprajitno Munadi
Scientific Contributions Oil and Gas Vol 9 No 1 (1986)
Publisher : Testing Center for Oil and Gas LEMIGAS

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.29017/SCOG.9.1.898

Abstract

Digital filtering is mathematical process which provides a means of filtering data numerically. The filtering process can be carried out in the frequency domain to discriminate signal and noise based on the frequency differencesThe digital band-pass frequency filtering has been effectively accomplished using a new type of digital filter. This filter is the result of compolving a boxcar spectral window with a frequency shifted Gaussian function which produces a very smooth transition between the pass-band and the stop-band region. The slope of the filter is controlled by the exponential coefficient of the Gaussian function. For a very narrow pass-band the exponential coefficient also controls the resolution of the filter.Experiments have been done with the Synthetic Vertical Seismic Profiles data to prove the performance of the filter and shows a good results. 
A Method For Generating Plane Wave And Zero-Offet Vsp Synthetic Seismograms Suprajitno Munadi
Scientific Contributions Oil and Gas Vol 8 No 1 (1985)
Publisher : Testing Center for Oil and Gas LEMIGAS

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.29017/SCOG.8.1.900

Abstract

Synthetic Vertical Seismic Profiles (VSP) seianograms are a useful aid to the interpretation of VSP re- conds, Plane wave VSP syntherics multiples and mode conversions can be computed rapldly n the frequency domain using a new recursive formulation. The method urilises the concept of "renultanz" phase related reflection and tranamission coefficients for a layer atack. High frequerncy signals can be handled with relative euse. The ability to control the order of the multiple avolds wraparound problems with the discrete Fourier transform. Several examples are used to lhustrate the method with relewance to seismic exploration.
SEISMO-ELECTRIC PHENOMENA FROM GRANITE CRACK CONTAINING CRUDE OIL Suprajitno Munadi
Scientific Contributions Oil and Gas Vol 30 No 1 (2007)
Publisher : Testing Center for Oil and Gas LEMIGAS

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.29017/SCOG.30.1.974

Abstract

Seismo-electric phenomena gained more attention from geophysicists over the last decade.The development of theoretical background and the success of laboratory experimentsas well as limited field applications give a lot of opportunities and hope as a meansfor providing exploration and production data. Seismo-electric effect accommodates anyphenomena which links seismic and electrical energy including seismic to electric conversionas well as electro kinetic in origin.Experiment has been conducted to prove that free ions can be considered to accumulateinside a granite crack containing crude oil which in turn can generate stream oscillatoryelectric current when a seismic wave hit the fracture. As a result, electric potential canbe detected at the mouth of the fracture which intersects the borehole. The environmentalnature of the mouth which is full of fluid facilitates the detection of high resolution seismoelectricsignal by simple electrodes which is made of metal.
THE EFFECT OF OIL CONTENT ON SONIC WAVE PROPAGATION (Analyses from Well Log Data) Suprajitno Munadi
Scientific Contributions Oil and Gas Vol 30 No 2 (2007)
Publisher : Testing Center for Oil and Gas LEMIGAS

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.29017/SCOG.30.2.983

Abstract

The effect of fluid content to the sonic wave propagation in the reservoir rock hasbeen studied experimentally using the well log data. Evidence shows that the water contentaffects the sonic wave propagation only in a specific interval, while oil content also affectsthe sonic wave propagation but at a specific low interval. There is a discontinuity wherethe effect of oil content changes suddenly with an increasing oil content. Higher than thisvalue it seems that there is no effect of oil content on sonic wave transit time.