scholarly journals Pluto 4D—Australia's first 4D over a gas field is an outstanding success

2018 ◽  
Vol 58 (1) ◽  
pp. 395 ◽  
Author(s):  
Larry Tilbury ◽  
Andre Gerhardt
Keyword(s):  
History Matching ◽  
Feasibility Studies ◽  
Seismic Survey ◽  
Gas Field ◽  
Water Contact ◽  
Depth Migration ◽  
Water Ingress ◽  
Noise Data ◽  
Excellent Control ◽  
4D Seismic

The Pluto 4D seismic survey is Australia’s first 4D survey acquired over a gas field and has been an outstanding success despite the prior high technical risk of not being able to detect 4D differences above the background noise. At the time of the Pluto 4D monitor survey, the Pluto field had been on production for three years and nine months and produced approximately 1 Tcf of gas. The first monitor survey was acquired by PGS between November 2015 and February 2016 using dual sources and 12 streamers of 7050 m (geostreamer configuration). Also of note was the use of steerable sources to assist with repeatability, and towing the streamers at 20 m to minimise noise. Data was processed by CGG to pre-stack depth migration (PreSDM), took 12 months to deliver and required significant interaction between Woodside geoscientists and CGG to ensure an excellent 4D product. 4D feasibility studies carried out before acquisition showed that saturation changes (related to water ingress) were expected to show strong 4D responses near the gas water contact (GWC) and would be interpretable if the monitor survey was run after approximately three to four years of production. If the monitor survey was delayed, it showed that the pressure response became too large, swamped the 4D differences and made interpretation difficult or impossible. Strong ‘hardening’ responses on the 4D difference volumes are interpreted as water ingress into the field. Hardening responses are seen in all reservoir sequences in the Triassic from the TR27 to the TR32 units and range from strong (obvious) to weak (possible). Several examples are shown – the strongest response is seen in the large Triassic (TR27.3) valley within an essentially shale prone unit, which shows water ingress into the valley and moving upwards from the GWC towards the producing well. The results/insights from the 4D data have provided excellent control points for the history matching of the Pluto Field.

Pluto gas field: Successful placement of an infill well based on 4D seismic monitoring

2020 ◽  
Vol 39 (7) ◽  
pp. 464-470
Author(s):  
Benjamin Peterson ◽  
André Gerhardt
Keyword(s):  
Feasibility Studies ◽  
Gas Production ◽  
Seismic Survey ◽  
Gas Field ◽  
Water Contact ◽  
North West ◽  
Water Ingress ◽  
Gas Fields ◽  
4D Seismic ◽  
Gas Expansion

Seismic 4D monitoring technology has not been as widely employed for gas fields as it has for oil. Many gas fields rely on depletion drive, which has a 4D seismic response that can be uncertain and difficult to predict. On the other hand, aquifer-supported gas fields with measurable water ingress have a reasonable chance of success in terms of generating an interpretable 4D amplitude signal. Pluto gas field in the North West Shelf of Australia falls into this category. Following discovery in 2005, Pluto was appraised by five wells, which found a consistent gas gradient and gas-water contact across the entire field and its various reservoirs. Gas production began in 2012. Time-lapse seismic feasibility studies concluded that gas-saturation changes could be observed with a monitor seismic survey acquired three to four years after first gas. The Pluto 4D Monitor 1 survey was acquired at the start of 2016 and revealed both hardening and softening anomalies. Hardening is interpreted as water ingress (expected) and softening as gas expansion (unexpected). The Pluto 4D results provided important insights into reservoir connectivity and discontinuities. Large hardening anomalies at the TR27 (lower) level can be clearly seen in the data, showing avenues for water ingress. More importantly, a large softening anomaly below the original gas-water contact in the TR29 (upper) reservoir is interpreted to be gas expansion into the aquifer created by a U-tubing effect around a possible barrier in the gas leg. This suggests that the entire TR29 reservoir may not be accessed by the producing PLA04 well. Based on this 4D interpretation, the PLA07 well was drilled and completed in 2019 to produce the TR29 gas updip from the gas expansion anomaly and to increase Pluto field recovery.

Exploration success on the North West Shelf via continuous application of seismic technologies

2009 ◽  
Vol 49 (1) ◽  
pp. 205
Author(s):  
Mark Thompson ◽  
M Royd Bussell ◽  
Michael Wilkins ◽  
Dave Tapley ◽  
Jenny Auckland
Keyword(s):  
Seismic Imaging ◽  
Leading Edge ◽  
Seismic Survey ◽  
Water Contact ◽  
North West ◽  
Depth Migration ◽  
Petroleum Systems ◽  
The North ◽  
Continuous Application ◽  
Near Term

Expansion of the North West Shelf Venture (NWSV) production infrastructure is driving plans for sequential development of the small satellite fields. The desire for additional gas reserves has fuelled increased exploration and appraisal drilling in recent years with encouraging results. The NWSV area is a complex geologic environment with multiple play levels, petroleum systems and trapping styles. Seismic imaging is poor in many areas, primarily due to multiple contamination. In 2004, the NWSV acquired the leading edge, regional Demeter 3D Seismic Survey. Since then, continuous application of improved processing techniques, such as 3D Surface-related Multiple Elimination (SRME) and Pre-Stack Depth Migration (PreSDM), have been key to providing significant imaging enhancements. Exploration drilling based on Demeter data resulted in three significant new gas discoveries. Pemberton–1 (2006) explored Triassic sub-cropping sands in a horst block at the southwestern end of the Rankin Trend. The well encountered an upside gas column due to the presence of intra-Mungaroo Formation shales providing a base-seal trapping geometry. Lady Nora–1 (2007) tested the fault block west of the Pemberton horst and encountered a 102 m gross gas column with gas on rock. The upside result accelerated a near term appraisal opportunity at Lady Nora–2 (2008). Persephone–1 (2006) drilled a down-thrown Legendre Formation dip closure in the Eaglehawk graben. Success relied on the sealing potential of the North Rankin Field bounding fault. In spite of pressure depletion associated with over 20 years of production, Persephone–1 encountered a 151 m gross gas column at virgin pressures and a different gas-water contact to North Rankin. The result demonstrated active and significant fault seal along the major North Rankin Field bounding fault. These recent, successful exploration wells have resulted in identification of follow-up drilling opportunities and a drive for ongoing seismic imaging improvements. The discoveries have material impacts on NWSV development plans for the Greater Western Flank and in the vicinity of the Perseus, North Rankin and Goodwyn gas fields.

The Babbage Field, Block 48/2a, UK North Sea

2020 ◽  
Vol 52 (1) ◽  
pp. 97-108 ◽  
Author(s):  
R. M. Phipps ◽  
C. J. Tiltman
Keyword(s):  
Seismic Imaging ◽  
Complex Salt ◽  
Reverse Time ◽  
Gas Field ◽  
Water Contact ◽  
Depth Migration ◽  
Reservoir Permeability ◽  
Northern Edge ◽  
Sandstone Formation ◽  
Volume Range

AbstractThe Babbage gas field was discovered in 1988 by exploration well 48/2-2 which drilled into the Permian-age lower Leman Sandstone Formation below a salt wall. Seismic imaging is compromised by the presence of this salt wall, which runs east–west across the southern part of the structure, creating uncertainties in depth conversion and in the in-place volumes. Pre-stack depth migration with beam and reverse time migrations appropriate for the complex salt geometry provided an uplift in subsalt seismic imaging, enabling the development of the field, which is located at the northern edge of the main reservoir fairway in a mixed aeolian–fluvial setting. Advances in artificial fracturing technology were also critical to the development: in this area, deep burial is associated with the presence of pore-occluding clays, which reduce the reservoir permeability to sub-millidarcy levels. The Babbage Field was sanctioned in 2008, based on an in-place volume range of 248–582 bcf; first production was in 2010. It produces from five horizontal development wells that were artificially fracced to improve deliverability of gas from the tight matrix. None of the wells has drilled the gas–water contact, which remains a key uncertainty to the in-place volumes, along with depth-conversion uncertainty below the salt wall.

Combining Saturation Changes and 4D Seismic for Updating Reservoir Characterizations

2006 ◽  
Vol 9 (05) ◽  
pp. 502-512 ◽  
Author(s):  
Arne Skorstad ◽  
Odd Kolbjornsen ◽  
Asmund Drottning ◽  
Havar Gjoystdal ◽  
Olaf K. Huseby
Keyword(s):  
Wave Velocity ◽  
Seismic Data ◽  
History Matching ◽  
Reservoir Characterization ◽  
Seismic Survey ◽  
Production Data ◽  
Reservoir Model ◽  
Simple Method ◽  
4D Seismic ◽  
Elastic Inversion

Summary Elastic seismic inversion is a tool frequently used in analysis of seismic data. Elastic inversion relies on a simplified seismic model and generally produces 3D cubes for compressional-wave velocity, shear-wave velocity, and density. By applying rock-physics theory, such volumes may be interpreted in terms of lithology and fluid properties. Understanding the robustness of forward and inverse techniques is important when deciding the amount of information carried by seismic data. This paper suggests a simple method to update a reservoir characterization by comparing 4D-seismic data with flow simulations on an existing characterization conditioned on the base-survey data. The ability to use results from a 4D-seismic survey in reservoir characterization depends on several aspects. To investigate this, a loop that performs independent forward seismic modeling and elastic inversion at two time stages has been established. In the workflow, a synthetic reservoir is generated from which data are extracted. The task is to reconstruct the reservoir on the basis of these data. By working on a realistic synthetic reservoir, full knowledge of the reservoir characteristics is achieved. This makes the evaluation of the questions regarding the fundamental dependency between the seismic and petrophysical domains stronger. The synthetic reservoir is an ideal case, where properties are known to an accuracy never achieved in an applied situation. It can therefore be used to investigate the theoretical limitations of the information content in the seismic data. The deviations in water and oil production between the reference and predicted reservoir were significantly decreased by use of 4D-seismic data in addition to the 3D inverted elastic parameters. Introduction It is well known that the information in seismic data is limited by the bandwidth of the seismic signal. 4D seismics give information on the changes between base and monitor surveys and are consequently an important source of information regarding the principal flow in a reservoir. Because of its limited resolution, the presence of a thin thief zone can be observed only as a consequence of flow, and the exact location will not be found directly. This paper addresses the question of how much information there is in the seismic data, and how this information can be used to update the model for petrophysical reservoir parameters. Several methods for incorporating 4D-seismic data in the reservoir-characterization workflow for improving history matching have been proposed earlier. The 4D-seismic data and the corresponding production data are not on the same scale, but they need to be combined. Huang et al. (1997) proposed a simulated annealing method for conditioning these data, while Lumley and Behrens (1997) describe a workflow loop in which the 4D-seismic data are compared with those computed from the reservoir model. Gosselin et al. (2003) give a short overview of the use of 4D-seismic data in reservoir characterization and propose using gradient-based methods for history matching the reservoir model on seismic and production data. Vasco et al. (2004) show that 4D data contain information of large-scale reservoir-permeability variations, and they illustrate this in a Gulf of Mexico example.

Tupi Nodes pilot: A successful 4D seismic case for Brazilian presalt reservoirs

2021 ◽  
Vol 40 (12) ◽  
pp. 886-896
Author(s):  
Nathalia Martinho Cruz ◽  
José Marcelo Cruz ◽  
Leonardo Márcio Teixeira ◽  
Mônica Muzzette da Costa ◽  
Laryssa Beatriz de Oliveira ◽  
...  
Keyword(s):  
Oil Recovery ◽  
History Matching ◽  
Oil And Gas ◽  
Feasibility Studies ◽  
Oil And Gas Industry ◽  
Time Lapse ◽  
Seismic Inversion ◽  
Carbonate Reservoirs ◽  
Ocean Bottom ◽  
4D Seismic

The oil and gas industry has established 4D seismic as a key tool to maximize oil recovery and operational safety in siliciclastic and low- to medium-stiffness carbonate reservoirs. However, for the stiffer carbonate reservoirs of the Brazilian presalt, the value of 4D seismic is still under debate. Tupi Field has been the stage of a pioneering 4D seismic project to field test the time-lapse technique's ability in monitoring production and water-alternating-gas (WAG) injection in the Brazilian presalt. Ocean-bottom node (OBN) technology was applied for the first time in the ultra-deep waters of Santos Basin, leading to the Tupi Nodes pilot project. We started with feasibility studies to forecast the presalt carbonate time-lapse responses. The minerals that constitute these carbonate rocks have an incompressibility modulus that is generally twice as large as those of siliciclastic rocks. This translates into discrete 4D signals that require enhanced seismic acquisition and processing techniques to be correctly detected and mapped. Consequently, two OBN seismic acquisitions were carried out. Time-lapse processing included the application of top-of-the-line processing tools, such as interbed multiple attenuation. The resulting 4D amplitude images demonstrate good signal-to-noise ratio, supporting both static and dynamic interpretations that are compatible with injection and production histories. To unlock the potential of 4D quantitative interpretation and the future employment of 4D-assisted history-matching workflows, we conducted a 4D seismic inversion test. Acoustic impedance variations of about 1.5% are reliably distinguishable beyond the immediate vicinity of the wells. These 4D OBN seismic surveys and interpretations will assist in identifying oil-bypassed targets for infill wells and calibrating WAG cycles, increasing oil recovery. We anticipate that studies of the entire Brazilian presalt section will greatly benefit from the results and conclusions already reached for Tupi Field.

Rock physics modelling and analysis of time-lapse seismic response in the Pyrenees Field, offshore Western Australia

2015 ◽  
Vol 55 (2) ◽  
pp. 470
Author(s):  
Stanislav Kuzmin ◽  
Mauricio Florez ◽  
Guy Duncan ◽  
Konstantinos Kostas
Keyword(s):  
Seismic Response ◽  
Coming Out ◽  
Significant Risk ◽  
Rock Physics ◽  
Time Lapse ◽  
Seismic Survey ◽  
Water Contact ◽  
Fluid Saturation ◽  
Oil Water ◽  
4D Seismic

Rock physics modelling of the time-lapse seismic response of the Pyrenees Field was carried out to evaluate the feasibility of monitoring reservoir drainage and performance. Initially, the purpose of 4D seismic was to monitor the upward displacement of the oil-water contact. It was recognised that the likelihood of gas breakout imposed a significant risk to the feasibility of monitoring the oil-water contact. Models for different scenarios were used to assess this uncertainty and demonstrated that, in either case, an observable change in seismic properties would occur, providing technical support for 4D seismic acquisition. The monitor seismic survey acquired in 2013, showed detectable changes in both interval velocity and reflectivity that was associated with gas coming out of solution in the reservoir, where depletion occurred below the bubble point. This agrees with pre-acquisition predictions based on rock physics modelling. Additional rock physics analysis was carried out to calibrate the observed 4D response to changes in both fluid saturation and effective stress.

Success story of integrated subsurface study to deliver a successful infill drilling: Buntal-5 case study

2021 ◽  
Author(s):  
B. Khoironi
Keyword(s):  
History Matching ◽  
Gas Field ◽  
Water Contact ◽  
Seismic Amplitude ◽  
Water Breakthrough ◽  
Geological Features ◽  
Open Hole ◽  
Geophysical Study ◽  
Infill Drilling ◽  
Geological Concept

Buntal is a mature gas field located in South Natuna Sea Block B PSC. The field was discovered by well Buntal-1 and delineated by appraisal well Buntal-2. The field consists of multi-stacked sandstone reservoirs, which were deposited under fluvial deltaic environment. The major Buntal reservoirs have been produced since 2004 from two subsea wells. Buntal-3 was producing from zones Beta-1 and Beta-2, while Buntal-4 was a horizontal well producing from Zone-1C. Both of those wells had loaded up prior to Buntal-5 drilling. This paper describes the details of a multidisciplinary approach taken for the proposal of Buntal-5 infill drilling. An integrated geological and geophysical study were carried out to quantify resources and uncertainties of the remaining thin unproduced zones. In total, there are 8 virgin zones as Buntal-5 initial target namely Beta-0, Zone-1A, Zone-1B, Zone-1D, Zone-1E, Zone-2B, Zone-3 and Zone-3A. Max-trough seismic amplitude was utilized to identify geological features across for each Buntal reservoir. The result was then combined with geological concept based on its depositional environment to justify a reasonably higher hydrocarbon volume which can not be estimated only by wells’ data. A reservoir simulation study was also carried out to not only to evaluate production potential from the virgin zones but also to capture upside potential from the produced zones. Simulation history matching result on Zone-1C revealed early water breakthrough experienced by Buntal-4 well due to water cresting phenomena which left significant gas reserves. This result added upside potential to Buntal-5 which initially only targeted marginal remaining unproduced zones. The well was drilled at the end of 2019 and proven to be a major success. Buntal-5 open hole logs data indicate thicker and better virgin zones reservoir quality as expected by integrated geological and geophysical study. Furthermore, significant remaining gas was encountered in Zone-1C with actual gas water contact was within the simulation result proving the water cresting theory, the zone itself add well’s gas-in-place by 30% on top of the unproduced zones’ gas-in-place.

Using 4D Seismic Surveys and History Matching to Estimate Critical and Maximum Gas Saturation

2014 ◽  
Author(s):  
Dennis Chinedu Obidegwu ◽  
Romain Louis Chassagne ◽  
Colin Macbeth
Keyword(s):  
History Matching ◽  
Seismic Surveys ◽  
Gas Saturation ◽  
4D Seismic

The method for modeling the development of a gas field on the basis of a hierarchy of mathematical models

2019 ◽  
Vol 5 (3) ◽  
pp. 69-82
Author(s):  
Vitaly P. Kosyakov ◽  
Amir A. Gubaidullin ◽  
Dmitry Yu. Legostaev
Keyword(s):  
Mathematical Models ◽  
Energy State ◽  
Reservoir Pressure ◽  
Gas Field ◽  
Water Contact ◽  
Simple Models

This article presents an approach aimed at the sequential application of mathematical models of different complexity (simple to complex) for modeling the development of a gas field. The proposed methodology allows the use of simple models as regularizers for the more complex ones. The main purpose of the applied mathematical models is to describe the energy state of the reservoir — reservoir pressure. In this paper, we propose an algorithm for adapting the model, which allows constructing reservoir pressure maps for the gas field, as well as estimating the dynamics of reservoir pressure with a possible output for determining the position of the gas-water contact level.

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