LONGTOM—CONFIRMATION OF A NEW PLAY IN OFFSHORE GIPPSLAND

2007 ◽  
Vol 47 (1) ◽  
pp. 91
Author(s):  
K.P. Lanigan ◽  
G. Bunn ◽  
J. Rindschwentner

The Longtom gas field was discovered in 1995, when the Longtom–1/ST1 wildcat well in the northern part of the offshore Gippsland Basin encountered dry gas in tight sandstones towards the base of the Latrobe Group, in what is now called the Admiral Formation of the Emperor Subgroup. In 2004 the Longtom–2/ST1 exploration well confirmed significant vertical and lateral extension of these prospective gas sands, and also provided very encouraging production test and core data. The recent Longtom–3 wells have demonstrated the viability of this new play by confirming significant lateral continuity of the thicker gas sands and demonstrating high gas flow rates. The history of the field’s discovery and appraisal illustrates how a multi-disciplinary and interactive approach, guided by innovative seismic inversion techniques and real-time petrophysical data, resulted in the successful planning and execution of the Longtom–3 drilling and evaluation program. The results of the wells and the outline of the field development plan illustrate how Longtom represents new production potential in this mature basin.

2019 ◽  
Vol 38 (6) ◽  
pp. 474-479
Author(s):  
Mohamed G. El-Behiry ◽  
Said M. Dahroug ◽  
Mohamed Elattar

Seismic reservoir characterization becomes challenging when reservoir thickness goes beyond the limits of seismic resolution. Geostatistical inversion techniques are being considered to overcome the resolution limitations of conventional inversion methods and to provide an intuitive understanding of subsurface uncertainty. Geostatistical inversion was applied on a highly compartmentalized area of Sapphire gas field, offshore Nile Delta, Egypt, with the aim of understanding the distribution of thin sands and their impact on reservoir connectivity. The integration of high-resolution well data with seismic partial-angle-stack volumes into geostatistical inversion has resulted in multiple elastic property realizations at the desired resolution. The multitude of inverted elastic properties are analyzed to improve reservoir characterization and reflect the inversion nonuniqueness. These property realizations are then classified into facies probability cubes and ranked based on pay sand volumes to quantify the volumetric uncertainty in static reservoir modeling. Stochastic connectivity analysis was also applied on facies models to assess the possible connected volumes. Sand connectivity analysis showed that the connected pay sand volume derived from the posterior mean of property realizations, which is analogous to deterministic inversion, is much smaller than the volumes generated by any high-frequency realization. This observation supports the role of thin interbed reservoirs in facilitating connectivity between the main sand units.


2001 ◽  
Vol 41 (2) ◽  
pp. 131
Author(s):  
A.G. Sena ◽  
T.M. Smith

The successful exploration for new reservoirs in mature areas, as well as the optimal development of existing fields, requires the integration of unconventional geological and geophysical techniques. In particular, the calibration of 3D seismic data to well log information is crucial to obtain a quantitative understanding of reservoir properties. The advent of new technology for prestack seismic data analysis and 3D visualisation has resulted in improved fluid and lithology predictions prior to expensive drilling. Increased reservoir resolution has been achieved by combining seismic inversion with AVO analysis to minimise exploration risk.In this paper we present an integrated and systematic approach to prospect evaluation in an oil/gas field. We will show how petrophysical analysis of well log data can be used as a feasibility tool to determine the fluid and lithology discrimination capabilities of AVO and inversion techniques. Then, a description of effective AVO and prestack inversion tools for reservoir property quantification will be discussed. Finally, the incorporation of the geological interpretation and the use of 3D visualisation will be presented as a key integration tool for the discovery of new plays.


2019 ◽  
Vol 9 (12) ◽  
pp. 2394 ◽  
Author(s):  
Yun-Cheng Liao ◽  
Bin Liu ◽  
Juan Liu ◽  
Sheng-Peng Wan ◽  
Xing-Dao He ◽  
...  

A high temperature (up to 950 °C) sensor was proposed and demonstrated based on a micro taper in-line fiber Mach–Zehnder interferometer (MZI) structure. The fiber MZI structure comprises a single mode fiber (SMF) with two micro tapers along its longitudinal direction. An annealing at 1000 °C was applied to the fiber sensor to stabilize the temperature measurement. The experimental results showed that the sensitivity was 0.114 nm/°C and 0.116 nm/°C for the heating and cooling cycles, respectively, and, after two days, the sensor still had a sensitivity of 0.11 nm/°C, showing a good stability of the sensor. A probe-type fiber MZI was designed by cutting the sandwiched SMF, which has good linear temperature responses of 0.113 nm/°C over a large temperature range from 89 to 950 °C. The probe-type fiber MZI temperature sensor was independent to the surrounding refractive index (RI) and immune to strain. The developed sensor has a wide application prospect in the fields of high temperature hot gas flow, as well as oil and gas field development.


2011 ◽  
Vol 51 (2) ◽  
pp. 693
Author(s):  
Peter Tingate ◽  
Monica Campi ◽  
Geoffrey O'Brien ◽  
John Miranda ◽  
Louise Goldie Divko ◽  
...  

Understanding the CO2 storage potential and petroleum prospectivity of the Gippsland Basin are critical to managing the resources of this region. Key controls on determining the prospectivity for CO2 storage and petroleum include understanding the fluid migration history and reservoir characteristics in the basin. Gippsland Basin hydrology, reservoir characteristics and petroleum systems are being studied to better understand how CO2 can be safely stored in the subsurface. Hydrocarbon migration pathways have been delineated using petroleum systems modelling. The latest hydrocarbon charge history data has been acquired to test the containment potential of individual structures along these migration pathways. The charge history results indicate the Golden Beach gas field has had a complex hydrocarbon fill history, and that early charge has migrated through the regional seal. The results also indicate that early oil charge was very common in the basin, including large structures that are now filled with gas (e.g. Barracouta). The results allow the regions with good CO2 containment potential to be delineated for further storage investigations. A new evaluation of the reservoir characteristics of the Latrobe Group—through porosity/permeability analysis and automated mineral analysis (AMA)—has provided insights into CO2 injectivity and capacity. The AMA results constrain the mineralogy and diagenetic history of the reservoirs and seals. In addition, the data highlights the presence of carbonates, glauconite and K-feldspar that are potentially reactive with injected CO2.


1971 ◽  
Vol 11 (1) ◽  
pp. 85 ◽  
Author(s):  
B. R. Griffith ◽  
E. A. Hodgson

The offshore Gippsland Basin, underlies the continental shelf and slope between eastern Victoria and Tasmania.The basin is filled with up to 25,000' of sediment, varying in age from Lower Cretaceous to Recent. The Lower Cretaceous section is represented by at least 10,000' of nonmarine greywackes of the Strzelecki Group. The overlying sediments of Upper Cretaceous to Eocene age comprise the interbedded sandstones, siltstones, shales and coals of the Latrobe Group, with a cumulative thickness of about 15,000'. Offshore, the Latrobe Group is overlain unconformably by up to 1500' of calcareous mudstones of the Lakes Entrance Formation and up to 5000' of Gippsland Limestone carbonates. Pliocene to Recent carbonates, reaching a maximum thickness of about 1000', complete the sedimentary section of the basin.Australia's first commercial offshore field, the Barracouta oil and gas field, was discovered in the Gippsland Basin in February 1965. Further exploratory drilling over the following two and a half years led to the discovery of the Marlin gas field and the Kingfish and Halibut oil fields.The principal hydrocarbon accumulations are reservoired by sediments of the Latrobe Group within closed structural highs on the Latrobe unconformity surface. Seal is provided by the mudstones and marls of the Lakes Entrance Formation and Gippsland Limestone.A field development programme was initiated immediately after Barracouta had been confirmed as a commercial gas reservoir. By the end of 1967, the Barracouta 'A' platform had been erected. Construction and positioning of the Marlin, Halibut and the two Kingfish platforms followed.To date development drilling has been completed on the Barracouta and Halibut fields, while development of the Marlin field has been temporarily suspended following completion of four wells. Development of the Kingfish oil field which commenced in March 1970, is still in a relatively early stage.The Barracouta field has been producing gas and oil since March and October, 1969 respectively. The Marlin gas field was put on stream in November, 1969 and the Halibut oil field in March 1970. As yet no wells drilled in the Kingfish oil field have been completed for production.The four fields provide a major source of hydrocarbons for the Australian market. By the end of September, 1970 cumulative production of sales quality gas from the Barracouta and Marlin fields was almost 23 BCF. Cumulative production of stabilised oil from Barracouta was 2 million barrels and over 26 million barrels from Halibut.


2021 ◽  
Author(s):  
Yongzhong Zhang ◽  
Hualin Liu ◽  
Weigang Huang ◽  
Zhaolong Liu ◽  
Baohua Chang

High permeability zones in the water-drive gas reservoir tend to act as dominant channels for formation water to invade into gas reservoir from the aquifer. The presence of high permeability zones results in uneven water flow front in reservoir and early water breakthrough in gas well, which seriously affects the gas field development. In this paper, conventional logging and production logging data are used to identify and characterize high permeability zones, so as to guide the optimization of development plan of Kela 2 gas field. A method to determine the lower limit of high permeability zones by using cumulative frequency curve of permeability distribution is proposed, and high permeability zones of 21 wells are identified. These high permeability zones account for 10–15% of the effective reservoir thickness in single wells, and they are mainly distributed in the middle of the Bashijiqike (K1bs) Formation (i.e., K1bs12, K1bs21 and K1bs22). The analysis of production logging data shows that the effective gas producing intervals only account for 29.2% of the total number of test intervals, most of which are related to high permeability zones. Further study shows that the high gas flow from the high permeability zones dominates the wellbore production profile, and the gas in low permeability zones flows vertically to the high permeability zones and horizontally to wellbore through these zones. Through the analysis of production profiles over the years and computer modelling, it is confirmed that water channelling occurred in some gas wells at the depth where the high permeability zones are located, which leads to a significant decline in production of these wells. Based on the study of distribution and behaviour characteristics of the high permeability zones, two suggestions on controlling inhomogeneous water invasion are put forward to realize the sustainable and stable production of the gas field.


1992 ◽  
Vol 32 (1) ◽  
pp. 67 ◽  
Author(s):  
K. A. Parker

The discoveries of the Katnook Field and, later, the Ladbroke Grove Field were significant milestones for hydrocarbon exploration in the southeast of South Australia as well as for the Otway Basin in general. The initial 1987 discovery at Katnook-1 of a relatively shallow gas accumulation in the basal part of the Eumeralla Formation was eclipsed in late 1988 at the Katnook-2 appraisal stage where deeper and more significant gas reserves were discovered in the Pretty Hill Sandstone.Technological improvement, in seismic acquisition, in particular, use of longer offset configurations and higher fold, and in filtering and correction techniques at the processing stage, are discussed in relation to improved geologic understanding. These aspects ultimately led to drilling success in both exploration and appraisal.At the deep Katnook discovery stage several significant problem areas remained unresolved. These related to uncertainties in vertical distribution of gas pay, level of a gas-water contact, and unreliable reserve estimates the result of the inability of conventional log analysis techniques to distinguish gas-bearing from water-bearing sands. Both in the evaluation of Katnook-2 and at the Katnook-3 appraisal stage, expensive cased-hole testing programs were undertaken to determine the size, extent and producibility of the gas accumulation. A key development between drilling Katnook-2 and Katnook-3 was the discovery of carbon dioxide-rich gas at Ladbroke Grove during 1989 in an adjacent structure to the south.The Katnook Field was the first commercial gas field development in the southeast, South Australian part of the Otway Basin, with gas sales commencing in March 1991, within a year of completing field appraisal. The discoveries, and subsequent development, have led to a renewed focus on the Otway Basin as a prospective hydrocarbon province.


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