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Zeinijahromi A.,University of Adelaide | Lemon P.,Santos Ltd. | Bedrikovetsky P.,University of Adelaide
Journal of Petroleum Science and Engineering | Year: 2011

Permeability decline during corefloods with varying water composition, especially with low salinity water, has been widely reported in the literature. It has often been explained by the lifting, migration and subsequent plugging of pores by fine particles, which has been observed in numerous core flood tests with altered water composition (salinity, pH) and temperature. This effect can be considered to provide a relatively simple method for mobility control during waterflooding. In previous research, the Dietz model for waterflooding in a layer-cake reservoir with a constant injection and production rate was combined with a particle detachment model to investigate the effect of fines migration and induced permeability decline on reservoir sweep efficiency. In this work, the analytical model was extended to waterflooding with a given pressure drop between injection and production wells. The modelling showed that permeability decline in the water swept zone, caused by the alteration of the injected water composition and induced fines migration, may be able to improve waterflood performance by delaying water breakthrough and reducing the water cut. © 2011 Elsevier B.V.

Oliver S.,Santos Ltd
Society of Petroleum Engineers - SPE/APPEA Int. Conference on Health, Safety and Environment in Oil and Gas Exploration and Production 2012: Protecting People and the Environment - Evolving Challenges | Year: 2012

In late 2011 the Queensland State Government of Australia declared the Cooper Creek Basin in South West Queensland to be a Wild River Area under the Wild River Act 2005. The Wild River Area covers a significant proportion of Santos' current tenements and future development interests in the area. The Wild Rivers Declaration is a highly prescriptive regulatory regime that sets out significant restrictions which would detrimentally impact on existing operations and future oil and gas development opportunities, including emerging coal seam and shale gas prospects in the proposed declaration area. It includes genera! prohibitions on certain activities across extensive areas of channel country and the imposition of setbacks for activities in proximity to watercourses. The issue first arose in late 2010 when the Queensland Government indicated its intent to declare the Cooper Creek Basin as a Wild River through its issue of a Declaration Proposal. During the 12 month consultation period that followed, Santos engaged with the Queensland Government regulators and Ministers to assist the Government to make a Wild Rivers Declaration that achieves a balance between protecting the natural values of the Cooper Creek and allowing the continuation of the sustainable development of the petroleum resources within the Cooper and Eromanga Basins. The paper will provide insight into Santos' experience in taking a lead role in responding to the significant new legislative regime proposed by Government. Key insights include the need for industry tobe proactive and take a role in educating the Government on the industry's operations andthe changes required to ensure compliance with the new regulatory requirements. It will also discuss broadlythe challenges associated with the changing regulatory environment including the role that politics can play and observes that we should continue to expect a 'Wild' ride whenparticipating in thelegislative developmentprocess. The significance of the Declaration is that the restrictions for petroleum activities imposed in the Cooper Creek Basin Wild Rivers Declaration may be imposed upon all Wild Rivers areas in Queensland. In addition, other Australian state governments are watching the implementation of Wild Rivers' legislation in Queensland and are considering the need for similar regulatory regimes in their jurisdictions. Copyright 2012, SPE/APPEA International Conferenceon Hearth, Safety, and Environment in Oil and Gas Exploration and Production.

Collins M.,Santos Ltd
Society of Petroleum Engineers - SPE/APPEA Int. Conference on Health, Safety and Environment in Oil and Gas Exploration and Production 2012: Protecting People and the Environment - Evolving Challenges | Year: 2012

The Santos Health & Well Being program has been running since 2006. Integrated with a range of proactive human resource initiatives implemented over a number of years and guided by Santos values, significant improvements in health related indicators as well as improvements in human resource outcomes have been achieved. These results are built on a foundation of leadership development, employee engagement, targeted interventions and a range of Santos policies that support and focus on people development and encouraging healthy environments across the business. Copyright 2012, SPE/APPEA International Conference on Health, Safety, and Environment in Oil and Gas Exploration and Production.

Gardner B.,Santos Ltd.
Society of Petroleum Engineers - 2014 SPE Artificial Lift Conference - North America | Year: 2014

Santos has produced oil from the Cooper Basin, central Australia since 1983. A range of artificial lift systems are used, dependent on fluid rate and reservoir depth with the beam pump the dominant artificial lift system. Historically the fleet experienced high subsurface failure frequency and increasing operating cost. Information regarding pump operating conditions and the root cause of failure was inconsistent in reporting standard and not readily available. As a consequence the details and mode of failure were not well understood. This paper will focus on analysis of beam pump failure root causes and trends, and how the operator has used this data combined with automated equipment to reduce failure frequency and operating cost. Santos started a program of beam pump automation in 2006. Before 2009, Santos relied on review of individual well files to determine pump operating history and failure mode. No central collation of well history or pump failure information was available. A database was built, which compiled failure details for more than 2,000 pump installations. This database has enabled run life, failure mode and frequency to be tracked and analysed. A program of automation and control upgrades to 85% of the beam pump population has provided greater visibility of operating conditions and parameters by means of telemetry to the office. This information in conjunction with the database is now used to better understand reasons for failure, and to design future downhole configurations as a result. In 2006, all Santos beam pumps were non-automated and had a failure frequency of 0.4 failures per well per year. Since the implementation of the automated fleet and the database, data shows frequency has reduced by 70% for automated wells. In comparison, the remaining non-automated beam pumps continue to have a failure frequency of 0.3 to 0.4. Since 2006 the beam pump well count has increased by 60% while the number of annual pump repairs has reduced by 30%. The data indicates failure modes are different on wells with automation. As an example, automated wells have a lower frequency of parted rods, resulting from better rod string design and control. This paper will assist operators to benchmark beam pump run life in similar operating conditions such as the Cooper Basin. It also presents data and findings to support the benefit a beam pump automation and control program may provide. Detailed understandings of failure modes have helped Santos and its joint venture partners gain significant economic benefit, and develop "Best Practice" guidelines for beam pump system design as a consequence.

Burgoyne M.,Santos Ltd | Shrivastava R.,Santos Ltd
Journal of Natural Gas Science and Engineering | Year: 2016

Stress (or pressure) dependence of coal permeability is a commonly observed and generally accepted dynamic behaviour that is often ignored from production performance forecasting. Reasons for this omission typically include (a) the difficulties in reliably characterizing stress dependent effects from a limited number of pressure buildup (PBU) tests, and (b) large uncertainties in our understanding of both the porosity and compressibility of coals. This paper demonstrates a new analytical workflow, and proposes a new set of equations that overcomes some of those limitations. Engineers can use this paper to analytically translate expected permeability changes with pressure, to productivity changes with pressure differences.This paper utilizes a slightly modified form of Palmer-Mansoori (P&M) model in a workflow that includes. 1: Estimation of coal cleat volume compressibility using permeability-depth trends. 2: Characterization of mechanical skins from interpreted apparent skins. 3: Calculation of stress dependent pseudo pressure (SDPP) - converting permeability changes with pressure to productivity changes with pressure differences - enabling the use of well productivities over time as part of a SDP characterization process. 4: The matching through regression of relative changes in well productivity indices in groups of wells - utilizing the SDPP approach - with a single stress dependent controlling parameter, in a way that is suited to extrapolating away from well control.Theoretical support for this approach is provided via derivations from published models. A methodology is outlined - sharing the results of a field example - to demonstrate the relative ease with which the analytical process can be applied. Further, pitfalls are highlighted of using well productivities as a direct proxy for permeability changes, or even utilizing coarse grid numerical simulation in the matching process. Finally, further applications and limitations of its application are also discussed.This paper addresses existing knowledge gaps in the coal bed methane (CBM) industry by providing a simple, yet efficient, workflow for characterizing and incorporating stress-dependence of permeability in CBM Reservoir Engineering. This is achieved through the application of new analytical equations to characterize stress dependent pseudo pressure, enabling the direct use of well productivity changes, and can be used standalone, or as a means to accelerate a numerical history matching workflow. © 2016 Elsevier B.V.

Guillen Falcon G.E.,Santos Ltd.
Society of Petroleum Engineers - SPE Asia Pacific Unconventional Resources Conference and Exhibition | Year: 2015

Early Permian Cattle Creek Coals in Fairview Field in Queensland Australia is an insitu multicomponent Coal Seam Gas Reservoir. The Early Permian East coals or Springwater play typically occur at depths between 1,100 m to 1,800 m. These medium volatile bituminous coals are characterized as having lower permeability (5 mD), a high gas content (10 - 15 m3/t daf), an elevated concentration of ethane and heavier hydrocarbon components (2 - 14% C2), and higher inerts concentration (0.2 - 12% CO2 3% N2) than found in many CSG fields. . An analysis and history match of the production data from existing appraisal wells with a particular emphasis on the produced gas composition and its variation with depletion was performed using both an in-house compositional simulator which used the extended Langmuir Isotherm as the basis for the equilibrium relationship between the free and the sorbed gas phase and a commercial compositional simulator. Methane, Carbon Dioxide, Ethane, Propane and Nitrogen were simulated during this study. The results showed potential differences between the produced gas composition obtained during well production (considering the adsorption/desorption behavior of a multicomponent gas in a coal seam reservoir) and the in-situ gas composition determined from gas sampling during desorption tests. Heating value profiles were generated and compared illustrating the potential impact of the reservoir dynamic behaviour. The results also showed how the produced concentration of N2 (free gas phase) can be 4 to 7 times higher than its insitu concentration and that a variation of up to 75% of the initial concentration in free gas phase of CO2 and C2H6 concentration is possible due to the variability of the isotherms indicated from core. Copyright 2015 Society of Petroleum Engineers.

Brew S.R.,Santos Ltd
74th European Association of Geoscientists and Engineers Conference and Exhibition 2012 Incorporating SPE EUROPEC 2012: Responsibly Securing Natural Resources | Year: 2012

In 2000 a full azimuth 3D seismic survey was acquired over an undeveloped coal seam gas field in order to determine detailed structure, seam thicknesses and fracture regimes. In 2010 this survey was reprocessed to determine whether it was possible to get reliable 'sweet spot' and stress indicators from the seismic. In the intervening 10 years several wells have been drilled with varying levels of production and hydraulic fracturing success. A few even had casing collapse during drilling as a result of extreme stress with a resultant loss of drill stem. Consequently, if seismic could identify localised stress azimuth and magnitude through seismic anisotropy then it would have a significant impact on any future development; particularly with the need for horizontal drilling for both environmental and production purposes. Wells drilled on the field, subsequent to the 3D acquisition, had image logs recorded and processed, thus it was possible to calibrate azimuthal anisotropic seismic attributes with those logs and quantify the results. The presentation discusses the acquisition geometry and the approach taken in the processing and analysis. Various comparisons are made to assess which attributes are key indicators of stress. Finally the results are reviewed and quantified.

Clarke F.,Santos Inc.
Society of Petroleum Engineers - Progressing Cavity Pumps Conference 2013 | Year: 2013

The Cooper Basin is one of Australia's largest onshore resource projects. It is geographically located in central Australia in a remote and harsh area commonly known as the "Outback". On behalf of its joint venture partners, Santos operates more than 400 oil wells and 820 gas wells covering an extended operating area of approximately 12,000 square miles. A variety of artificial lift systems are used dependent on reservoir depth and fluid rate. This paper will focus on the application of Progressing Cavity Pumps (PCP) with a review of historical run life data and key lessons learned from 2004 to 2012. Santos installed its first PCP system in 1990. The trial was considered unsuccessful as a result of a pump failure occurring within a matter of days. No further trials of a PCP system were undertaken until 2004. This second 2 well trial was able to demonstrate the operability of the PCP system by achieving run lives of 180 and 250 days. These results were encouraging enough to move forward with expanded trials in a wider range of reservoirs located in various fields. The peak of the PCP implementation program in the Cooper Basin reached 145 installations in 2008. Unfortunately many of the applications fell outside of newly understood technical limits. Consequently a number of subsurface failures occurred which resulted in many unplanned workovers. As a result of poor PCP reliability, a change to more dependable forms of artificial lift was undertaken. The total PCP installation base has decreased to 38 systems of which 18 are operating in one particular field achieving pump run lives of 400 to 800 days. This paper will assist operators to benchmark PCP system performance in similar light oil applications as found in the Cooper Basin. Additionally, the paper will outline a set of technical limits developed from our operating experience and lastly, it will provide a guideline to understand the risks associated with operating PCP systems in a light oil application. Copyright 2013, Society of Petroleum Engineers.

Waldron A.R.,Santos Ltd | Camac B.A.,Santos Ltd
Leading Edge | Year: 2016

In 2014, the Santos-operated Cooper Basin Joint Venture hydraulically fracture-stimulated 465 zones from tight-gas-sand and unconventional reservoirs. Microseismic monitoring technology was introduced to reduce the technical risk associated with frack programs through higher confidence in calibrated and optimized frack models for conventional-sand, tight-sand, and shale targets. Ths would provide cost reductions through minimizing zones of frack overlap and reserves enhancement via optimized field-development planning through targeted infill field development via early recognition of well placement, spacing and identified drainage patterns, and frack-stage spacing.

Clarkson C.R.,University of Calgary | Jensen J.L.,University of Calgary | Chipperfield S.,Santos Ltd
Journal of Natural Gas Science and Engineering | Year: 2012

There has been a rapid evolution of technology used to evaluate unconventional gas reservoir and hydraulic-fracture properties, and there currently are few standardized procedures to be used as guidance. Therefore, more than ever, petroleum engineers and geoscientists are required to question data sources and have an intimate knowledge of evaluation procedures.We propose a workflow for the optimization of unconventional gas reservoir (UGR) field development to guide discussion of UGR evaluation. Critical issues related to reservoir sample and log analysis, rate-transient and production data analysis are raised. Further, we have provided illustrations of each step of the reservoir evaluation process using tight gas examples. Our intent is to provide some guidance for best practices. In addition to reviewing existing methods for reservoir evaluation, we introduce new methods for measuring pore size distribution (small-angle neutron scattering), evaluating core-scale heterogeneity, log-core calibration, and evaluating core/log data trends to assist with scale-up of core data. Our focus in this manuscript is on tight and shale gas reservoirs. © 2012 Elsevier Ltd.

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