Hybrid Method: Surface Geochemical and CWT Gamp for Reducing the Risk of Exploration in the Sanga Sanga Area, Kutai Basin, East Kalimantan, Indonesia

2021 ◽  
Author(s):  
A. M. Putranto
Keyword(s):  
Hybrid Methods ◽  
Low Frequency ◽  
Threshold Value ◽  
Transformation Method ◽  
Source Rocks ◽  
Positive Sign ◽  
Seismic Attribute ◽  
Hydrocarbon Production ◽  
East Kalimantan ◽  
Seismic Lines

Sanga Sanga Block is a mature field that has been producing more than 50 years. In 2018, the operatorship has been awarded to PT. PERTAMINA together with 4 exploration wells as firm commitment for the next three years. Geologically, the proven fields in the Sanga Sanga area is a combination of both structural and stratigraphic traps. The study area was deposited in a deltaic environment which is prolific for its petroleum system elements such as reservoir, seal, and source rocks. The exploration objectives are clearly to prove the resources portfolio into reserve and sustain hydrocarbon production in the Sanga Sanga block. Hybrid methods, both Surface Geochemical and CWT Gamp, are constructed to identify and predict the presence of hydrocarbon accumulation. Surface Geochemical uses a direct (Acid Extracting Soil Gas & Fluoresence Analysis) and an indirect (Microbial Technique) method. The combination of both direct and indirect methods shows that signs of anomaly occurred in areas that are geologically potential for exploration by using a minimum threshold value based on analogues from dry exploration wells. The correlation of low anomaly with dry wells is nearly 90%. CWT Gamp is a transformation method of seismic attribute frequency by comparing low frequency anomalies as Direct Hydrocarbon Indicators in seismic data. This method has been applied to 3D and 2D seismic lines and resulted a good (60% – 70%) hydrocarbon correlation (DHI) at frequencies between 12-25 Hz. Combination of those methods provides a positive sign for the position of exploration wells in Sanga Sanga area and clearly boosts the confidence of the placement of exploration well, especially in delta prone areas which are very high in structural and stratigraphic trap systems.

A possible new hydrocarbon play, offshore central West Greenland

1998 ◽  
pp. 28-30
Author(s):  
Nina Skaarup ◽  
James A. Chalmers
Keyword(s):  
Seismic Data ◽  
Mineral Resources ◽  
Source Rocks ◽  
Bright Spot ◽  
Offshore Area ◽  
West Greenland ◽  
The Government ◽  
Structural Closure ◽  
Multichannel Seismic Data ◽  
Seismic Lines

NOTE: This article was published in a former series of GEUS Bulletin. Please use the original series name when citing this article, for example: Skaarup, N., & Chalmers, J. A. (1998). A possible new hydrocarbon play, offshore central West Greenland. Geology of Greenland Survey Bulletin, 180, 28-30. https://doi.org/10.34194/ggub.v180.5082 _______________ The discovery of extensive seeps of crude oil onshore central West Greenland (Christiansen et al. 1992, 1994, 1995, 1996, 1997, 1998, this volume; Christiansen 1993) means that the central West Greenland area is now prospective for hydrocarbons in its own right. Analysis of the oils (Bojesen-Koefoed et al. in press) shows that their source rocks are probably nearby and, because the oils are found within the Lower Tertiary basalts, the source rocks must be below the basalts. It is therefore possible that in the offshore area oil could have migrated through the basalts and be trapped in overlying sediments. In the offshore area to the west of Disko and Nuussuaq (Fig. 1), Whittaker (1995, 1996) interpreted a few multichannel seismic lines acquired in 1990, together with some seismic data acquired by industry in the 1970s. He described a number of large rotated fault-blocks containing structural closures at top basalt level that could indicate leads capable of trapping hydrocarbons. In order to investigate Whittaker’s (1995, 1996) interpretation, in 1995 the Geological Survey of Greenland acquired 1960 km new multichannel seismic data (Fig. 1) using funds provided by the Government of Greenland, Minerals Office (now Bureau of Minerals and Petroleum) and the Danish State through the Mineral Resources Administration for Greenland. The data were acquired using the Danish Naval vessel Thetis which had been adapted to accommodate seismic equipment. The data acquired in 1995 have been integrated with the older data and an interpretation has been carried out of the structure of the top basalt reflection. This work shows a fault pattern in general agreement with that of Whittaker (1995, 1996), although there are differences in detail. In particular the largest structural closure reported by Whittaker (1995) has not been confirmed. Furthermore, one of Whittaker’s (1995) smaller leads seems to be larger than he had interpreted and may be associated with a DHI (direct hydrocarbon indicator) in the form of a ‘bright spot’.

Maintaining line of sight in oil and gas exploration: A case study from Mahakam Delta, Indonesia

2020 ◽  
Vol 39 (8) ◽  
pp. 558-565
Author(s):  
Balakrishnan Kunjan ◽  
Witan Ardjakusumah ◽  
Kevin McDonald ◽  
Hannah Booth ◽  
Seda Rouxel ◽  
...  
Keyword(s):  
Oil And Gas ◽  
Airborne Gravity ◽  
Quality Of Data ◽  
Depth Migration ◽  
Oil And Gas Exploration ◽  
East Kalimantan ◽  
Well Data ◽  
Technical Effort ◽  
Seismic Lines ◽  
Over Time

In all exploration processes, the evaluation of basins, permits, and individual prospects changes over time with incremental availability and quality of data, technical effort expended, and knowledge gained. The NU prospect, located in the Mahakam Hilir PSC (East Kalimantan), is an example in which geologic chance of success (GCOS) predictions can change over time with increasing acquisition and availability of geophysical and geologic data and the studies done on them. We show how studies done on any one prospect or group of prospects can progressively increase/decrease the chance of at least one success in an exploration campaign of several wells. After a series of four wells was drilled in the PSC, which did not deliver commercial success, a change in approach was required to continue exploration. This included the acquisition of airborne gravity gradiometry data, initial trial prestack depth migration (PSDM) reprocessing of two key 1989 vintage 2D lines, acquisition of vintage well data from four Sambutan Field wells, acquisition of nine vintage 2D seismic lines over the field, and PSDM reprocessing of the nine 2D seismic lines. All data were then integrated to build a new geologic model. As a result, the NU prospect GCOS progressively moved from less than 10% to nearly 40%.

Sparse spectral attributes to detect hydrocarbons: A case study from deep dolomite reservoirs

2019 ◽  
Vol 7 (3) ◽  
pp. T701-T711
Author(s):  
Jianhu Gao ◽  
Bingyang Liu ◽  
Shengjun Li ◽  
Hongqiu Wang
Keyword(s):  
Seismic Data ◽  
Signal To Noise Ratio ◽  
Low Frequency ◽  
Spectral Amplitude ◽  
Data Set ◽  
Frequency Spectra ◽  
Hydrocarbon Production ◽  
Hydrocarbon Detection ◽  
Time Frequency ◽  
Gas Bearing

Hydrocarbon detection is always one of the most critical sections in geophysical exploration, which plays an important role in subsequent hydrocarbon production. However, due to the low signal-to-noise ratio and weak reflection amplitude of deep seismic data, some conventional methods do not always provide favorable hydrocarbon prediction results. The interesting dolomite reservoirs in Central Sichuan are buried over an average depth of 4500 m, and the dolomite rocks have a low porosity below approximately 4%, which is measured by well-logging data. Furthermore, the dominant system of pores and fractures as well as strong heterogeneity along the lateral and vertical directions lead to some difficulties in describing the reservoir distribution. Spectral decomposition (SD) has become successful in illuminating subsurface features and can also be used to identify potential hydrocarbon reservoirs by detecting low-frequency shadows. However, the current applications for hydrocarbon detection always suffer from low resolution for thin reservoirs, probably due to the influence of the window function and without a prior constraint. To address this issue, we developed sparse inverse SD (SISD) based on the wavelet transform, which involves a sparse constraint of time-frequency spectra. We focus on investigating the applications of sparse spectral attributes derived from SISD to deep marine dolomite hydrocarbon detection from a 3D real seismic data set with an area of approximately [Formula: see text]. We predict and evaluate gas-bearing zones in two target reservoir segments by analyzing and comparing the spectral amplitude responses of relatively high- and low-frequency components. The predicted results indicate that most favorable gas-bearing areas are located near the northeast fault zone in the upper reservoir segment and at the relatively high structural positions in the lower reservoir segment, which are in good agreement with the gas-testing results of three wells in the study area.

scholarly journals A SFTD Algorithm for Optimizing the Performance of the Readout Strategy of Residence Time Difference Fluxgate

Sensors ◽  
2018 ◽  
Vol 18 (11) ◽  
pp. 3985 ◽  
Author(s):  
Siyu Chen ◽  
Yanzhang Wang ◽  
Jun Lin
Keyword(s):  
Residence Time ◽  
Time Domain ◽  
Signal To Noise Ratio ◽  
Low Frequency ◽  
Transformation Method ◽  
Time Difference ◽  
Single Frequency ◽  
Time Frequency ◽  
Frequency Magnetic Field ◽  
The Time Domain

Residence time difference (RTD) fluxgate sensor is a potential device to measure the DC or low-frequency magnetic field in the time domain. Nevertheless, jitter noise and magnetic noise severely affect the detection result. A novel post-processing algorithm for jitter noise reduction of RTD fluxgate output strategy based on the single-frequency time difference (SFTD) method is proposed in this study to boost the performance of the RTD system. This algorithm extracts the signal that has a fixed frequency and preserves its time-domain information via a time–frequency transformation method. Thereby, the single-frequency signal without jitter noise, which still contains the ambient field information in its time difference, is yielded. Consequently, compared with the traditional comparator RTD method (CRTD), the stability of the RTD estimation (in other words, the signal-to-noise ratio of residence time difference) has been significantly boosted with sensitivity of 4.3 μs/nT. Furthermore, the experimental results reveal that the RTD fluxgate is comparable to harmonic fluxgate sensors, in terms of noise floor.

Rogue Wave and Breather Structures with “High Frequency” and “Low Frequency” in 𝒫𝒯-Symmetric Nonlinear Couplers with Gain and Loss

2016 ◽  
Vol 71 (10) ◽  
pp. 961-969 ◽  
Author(s):  
Dang-Jun Yu ◽  
Jie-Fang Zhang
Keyword(s):  
High Frequency ◽  
Rogue Wave ◽  
Low Frequency ◽  
Zero Solution ◽  
Rogue Waves ◽  
Transformation Method ◽  
Rational Solutions ◽  
Plane Wave Solution ◽  
Gain And Loss ◽  
Basic Characteristics

AbstractBased on the modified Darboux transformation method, starting from zero solution and the plane wave solution, the hierarchies of rational solutions and breather solutions with “high frequency” and “low frequency” of the coupled nonlinear Schrödinger equation in parity-time symmetric nonlinear couplers with gain and loss are constructed, respectively. From these results, some basic characteristics of multi-rogue waves and multi-breathers are studied. Based on the property of rogue wave as the “quantum” of pattern structure in rogue wave hierarchy, we further study the novel structures of the superposed Akhmediev breathers, Kuznetsov-Ma solitons and their combined structures. It is expected that these results may give new insight into the context of the optical communications and Bose-Einstein condensations.

The Frequency Effects on Fatigue Threshold of PVC-M and PVC-U in Air and Water Medium

2008 ◽  
Vol 41-42 ◽  
pp. 183-187
Author(s):  
N. Samat ◽  
Alan Whittle ◽  
Mark Hoffman
Keyword(s):  
Stress Ratio ◽  
Low Frequency ◽  
Threshold Value ◽  
Cyclic Fatigue ◽  
Fatigue Threshold ◽  
Water Medium ◽  
Chlorinated Polyethylene ◽  
Frequency Effects ◽  
Testing Environment ◽  
Impact Modifier

The cyclic fatigue threshold value (Kth) of PVC materials with (PVC-M) and without (PVC-U) impact modifier was determined and compared in air and water environments. The PVCM specimens contain 6 pphr of chlorinated polyethylene (CPE) impact modifier. The testing was undertaken at a stress ratio of R=0.1 and fatigue threshold was evaluated at 3 different frequencies: 1Hz, 7Hz and 20Hz. Frequency noticeably affected the fatigue threshold value; regardless of the testing environment; at low frequency the fatigue threshold of PVC-M was below PVC-U, however, this difference gradually decreased with increasing frequency as Kth of PVC-M increased but Kth of PVC-U remained constant. This trend was accelerated in water where a higher of fatigue threshold, Kth, was also observed. A lower fatigue threshold of PVC-M than PVC-U is associated with the presence of CPE particles. The absorption of water into the PVC matrix was evident with the formation of nodular structures observed on the fracture surface. The presence of the nodular structures (at regions close to the threshold) has retarded the fibrillation of crazes, which then blunted the crack propagation.

The Great Australian Bight – from AVO prospectivity screening to potentially drillable targets in one of the world's remaining untapped basins

2017 ◽  
Vol 57 (2) ◽  
pp. 793
Author(s):  
Dushyan Rajeswaran ◽  
Marcin Przywara
Keyword(s):  
Low Frequency ◽  
Structural Complexity ◽  
Source Rocks ◽  
High Definition ◽  
Depth Migration ◽  
Velocity Models ◽  
Structural Style ◽  
Petroleum Resource ◽  
Dual Sensor ◽  
Well Data

The Ceduna Sub-basin in Australia’s southern margin offers an untapped opportunity for significant petroleum resource as part of the global exploration portfolio. Analogous to the prolific Niger delta in both size and structural style, this highly-extensional province contains up to 15 km of largely untested post-rift sediments including two widespread Late Cretaceous deltas linked to world-class oil-prone marine Cretaceous source rocks. Regional interpretation of legacy 2D seismic across the Bight Basin brings the sheer scale and structural complexity of this giant Cretaceous depocentre into perspective, but it is only through the detailed analysis of 8001 km2 of dual-sensor towed streamer 3D seismic that its true potential can be quantified. Rigorous phase and amplitude AVO QC of the pre-stack information, coupled with optimised velocity models fed into the depth migration sequence, have ensured amplitude fidelity and phase stability across all offset ranges. This has enabled a systematic and robust exploration workflow of AVO analysis and pre-stack inversion despite limited well data. Numerous dual-sensor case studies have nevertheless demonstrated these Relative Acoustic Impedance and Vp/Vs volumes to be reliably robust for prospect de-risking because of the extended low frequency bandwidth. Frontier screening supported by a partially-automated high-resolution stratigraphic framework has led to the identification of numerous prospects at multiple stratigraphic levels across the survey area. This includes isolation of laterally extensive and vertically amalgamated fan-like structures within the shallow Hammerhead delta using horizon-constrained high-definition spectral decomposition, and the extraction of potential AVO anomalies within the deeper structurally-controlled White Pointer sands draped across large gravity-driven listric growth faults.

Detection of a lactate threshold during incremental exercise?

1989 ◽  
Vol 67 (2) ◽  
pp. 885-888 ◽  
Author(s):  
R. H. Morton
Keyword(s):  
Anaerobic Threshold ◽  
Threshold Value ◽  
Work Load ◽  
Continuous Model ◽  
Transformation Method ◽  
Load Range ◽  
Segmented Model ◽  
First Derivative ◽  
Modeling Methodology ◽  
Divergence Of Opinion

An important question in the study of the exercise response is the real or imaginary nature of the anaerobic threshold, and mathematical modeling techniques have been invoked to assist in resolving this issue. Two opposing views with competing data models recently published in this journal are criticized. One view suggests a segmented model with a discontinuous first derivative at the threshold. The other suggests a continuous model over the whole work load range, implying the anaerobic threshold to be imaginary. However, neither group of authors has devoted proper rigorous attention to the models they use. Had this been done, some of the divergence of opinion may have been avoided. Ideal data from an alternate segmented model that has a continuous first derivative at the threshold are considered for comparative purposes. This suggests that the log-log transformation method may well lead to improved detection of a threshold when one exists, although the estimates of the threshold value obtained are unreliable. Modeling methodology is a useful approach to the resolution of scientific issues, but there exist fundamental implications and alternatives that must be fully recognized.

Decay Instability of an Electromagnetic Wave Incident on a Weakly-Inhomogeneous Magnetised Plasma

1982 ◽  
Vol 37 (2) ◽  
pp. 97-101
Author(s):  
Bhimsen K. Shivamoggi
Keyword(s):  
Electromagnetic Wave ◽  
Pump Wave ◽  
Low Frequency ◽  
Langmuir Wave ◽  
Density Perturbation ◽  
Threshold Value ◽  
Wave Incident ◽  
Ion Acoustic Wave ◽  
Decay Instability ◽  
Electromagnetic Wave Incident

Abstract This paper considers the parametric decay of an electromagnetic wave incident on a weakly-inhomogeneous magnetised plasma into a Langmuir wave and an ion-acoustic wave. The Vlasov model is used in order to calculate the low-frequency electron-density perturbation produced by the beating of the side-band modes with the pump wave. The results show that the threshold value of the pump wave to undergo a decay instability drops in the presence of an inhomogeneity in the plasma.

scholarly journals Experimental Study of a Multipoint Random Dynamic Loading Identification Method Based on Weighted Average Technique

2019 ◽  
Vol 2019 ◽  
pp. 1-10
Author(s):  
Xiaonan Gai ◽  
Kaiping Yu
Keyword(s):  
Dynamic Loading ◽  
Thermal Protection ◽  
Low Frequency ◽  
Weighted Average ◽  
Threshold Value ◽  
Structure Identification ◽  
Load Spectrum ◽  
Average Technique ◽  
Identification Method ◽  
Actual Load

Most of random dynamic loading identification research studies are about the original inverse pseudoexcitation method which does not fundamentally reduce the negative effect of ill-conditioned frequency response function matrix on accuracy of loading identification. This paper describes a new improved method based on weighted average technique to reduce peak errors between identified load spectrum and the actual load spectrum near some natural frequencies. Meanwhile, relative error of root mean square value between identified load and the actual load is reduced. The introduced selection method of threshold value is innovative which is the key of weighted average technique. This improved loading identification method is successfully applied to experiments of cantilever beam and thermal protection composite plate structure. Identification results prove that the proposed method is valid by good agreement between identified power spectrum density and the actual one. Moreover, this method has higher accuracy than inverse pseudoexcitation method in low-frequency band.

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