Ghosh, Pinaki (The University of Texas at Austin) | Zepeda, Angel (The University of Texas at Austin) | Bernal, Gildardo (The University of Texas at Austin) | Mohanty, Kishore (The University of Texas at Austin)
Waterflood in low permeability carbonate reservoirs (<50 mD) leaves behind a substantial amount of oil due to capillary trapping and poor sweep. Addition of polymer to the injected water increases the viscosity of the aqueous phase and decreases the mobility ratio, thus, improving the sweep efficiency and oil production from the tight formations. Performance of current synthetic EOR polymers is limited by salinity, temperature and injectivity issues in low permeability formations. Mechanical shear degradation can be applied to high molecular weight synthetic polymers to improve the injectivitiy; but makes the process less economical due to significant viscosity loss and consequent increase in polymer dosage. Recently, a different class of polymer has been developed called "hydrophobically modified associative polymers (AP)". The primary goal of this work is to investigate the performance of associative polymers in low permeability carbonate reservoirs. We compare the performance of associative polymers with that of conventional HPAM polymers in low permeability formations. A low molecular weight associative polymer was investigated as part of this study. A detailed study of polymer rheology and the effect of salinity at the reservoir temperature (60 °C) was performed. Additional experiments were performed in bulk and porous media to investigate the synergy of associative polymers with hydrophilic surfactant blends at different brine salinities. Single phase polymer flow experiments were performed in outcrop Edwards Yellow and Indiana limestone cores of low permeability to determine the optimum polymer concentration to achieve the desired in-situ resistance factor (or apparent viscosity). Similar experiments were performed with HPAM polymer for a comparative study. Results showed successful transport of this associative polymer in low permeability formations after a small degree of shear degradation. The resistance factors for the associative polymer were higher than those for HPAM. Shear degraded polymers showed significant improvement in polymer transport in lower permeability cores with reduction in RRF.
This paper summarizes a technology using SMP to provide downhole sand control in openhole environments. With multistage operations becoming the industry norm, operators need easily deployable diversion technologies that will protect previously stimulated perforations and enable addition of new ones. This paper reviews several aspects of the use of in-stage diversion. Development of a new polymer composite that degrades via hydrolysis in hot water or brine holds potential for use in structural applications for intervention-less downhole tools. The polymer-injection project in the Dalia field, one of the main fields of Block 17 in deepwater Angola, represents a world first for both surface and subsurface aspects.
Polymer flooding in sensitive areas can require the transport of polymer fluids over long distances. Conventional wisdom limits transport distance or degradation occurs. This paper argues that critical velocity, not distance, is the controlling factor. Polymer flooding has been used to enhance the production of oil from mature fields in Oman. This article discusses the trial of several approaches to improve the treatment of water produced from these fields.
Researchers from Chevron are looking into a new approach to understand the drivers of polymer hydration. How might this affect the design of mixing systems in the field, and could it affect offshore EOR applications? Fluid Efficiency and Rhapsody Venture will partner to refine and launch a new molecular technology to improve the flow in pipelines. In this second article of a series covering water management in hydraulic fracturing (HF) in unconventional resources, the properties and characteristics of the flowback fluids are discussed, together with the general categories of technologies that are best suited to treat them. This is the first of several articles on the subject of water management for unconventional hydraulic fracturing.
The strategy supports the Maximise Economic Recovery from UK Oil & Gas Strategy and Vision 2035, whose goal is to achieve £140 billion additional gross revenue from UKCS production by that time. The projects are designed to reduce technical risks in enhanced oil recovery and expand application of EOR methods in conventional and unconventional reservoirs. In recent years, some effort has been made to use EOR techniques, particularly CO2 injection, to extract additional oil and gas from unconventional resources. This has the potential to change the dynamics (again) of oil production from these tight and difficult reservoirs. One of my best moments is to have made the technical case for polymer flooding and to see the fruits of this several decades later.
The Italian operator reported positive appraisal and exploration results from wells drilled some 10,000 km apart. The five discoveries combined hold an estimated 1.8 billion bbl of light oil in place. Conventional oil and gas discovered resources in 2019 are on pace to rise 30% from last year and reach their highest level since the beginning of the industry downturn. Here, a recap of the first quarter's 15 biggest oil and gas discoveries, which altogether are propelling the increase. The startup of the 1300-m water depth field is Eni’s fifth new field since 2014 in its West End development offshore Angola.
Aker Solutions and FSubsea have agreed to a joint venture, named FASTSubsea, to help operators increase oil recovery. Researchers from Chevron are looking into a new approach to understand the drivers of polymer hydration. How might this affect the design of mixing systems in the field, and could it affect offshore EOR applications? A pilot project demonstrates that facilities design plays an important role in providing sources of CO2 for the gas-handling process for injection into a carbonate formation as a tertiary recovery mechanism. The paper discusses the main factors affecting CO2 corrosion, provides an assessment of what to look for in major equipment, and details recommended material of construction and corrosion mitigation/control methods.
Total’s Egina floating production, storage, and offloading vessel is its largest ever, weighing 220,000 tonnes and measuring 330-m-long by 60-m-wide. It's equipped to produce up to 200,000 B/D and hold up to 2.3 million bbl of oil. Total advanced its global deepwater campaign 29 December with the launch of production from the Egina Field 150 km offshore Nigeria. The Egina floating production, storage, and offloading vessel, which Total says is its largest ever, will be connected to 44 subsea wells and produce up to 200,000 B/D of oil. The field lies in 1600 m of water on Oil Mining Lease (OML) 130.
Even with oil and gas prices at historical lows, top quality resources continue to be developed to meet the global demand of approximately 91 million B/D of oil and 332 Bcf/D of natural gas. TWA Forum Section Editors Craig Frenette, Samuel Ighalo, Winston Kosasi, and Rodrigo Terrazas interviewed experts from a diverse set of project types and discussed the development of the projects in the current economic context. Logan Popko, manager of asset development at Cenovus Energy speaks on the Christina Lake oil sands project; Ron Dusterhoft, technology fellow for production enhancement at Halliburton, talks about unconventional shale assets; Pete Hagen, general manager, commercial, at Chevron Australia, shares his insight on the Gorgon and Wheatstone liquefied natural gas projects; and Daniel Picard, special adviser to the director of the Libra Project, Petrobras (on secondment from Total), focuses on the offshore pre-salt megaproject, Libra, in Brazil. Logan Popko (LP): Despite the recent surge in oil supply from US tight oil plays and international production, high-quality, large volume resources continue to be scarce across the world and I believe that development of the Canadian oil sands will be critical to meeting the world's increasing energy demand. The technology we apply at the Christina Lake oil sands project is called steam-assisted gravity drainage (SAGD). It involves drilling horizontal wells to target a resource that is too deep to mine and then injecting steam into it to mobilize oil that can be as hard as a hockey puck at initial reservoir conditions.
Time lapse seismic is a proven technology for reservoir monitoring. It allows accessing useful information about the fluid movement, pressure changes and so on. This technology, however, has still some limitations in term of area of application. Shallow marine Middle East carbonate reservoirs are one of them.
In order to test this limit, ADMA-OPCO performed a 4D pilot (OBC/OBC) over a giant carbonate field, where the 2013 monitor has repeated the geometry of the 1994 base (parallel shooting). In this paper, we describe the challenges of the 4D processing of this data, the applied solutions and some results.
The water bottom over the pilot area ranges from 15 to 25 m. The main challenges of this 4D processing are: Geometry errors in the legacy OBC data: they have negligible impact in 3D but they increase the 4D noise. Significant time was spent correcting these errors. Noise contamination: the 2C component over the area is highly contaminated by Scholte waves and guided waves. Additionally, the geophone of the monitor data was highly impacted by current noise. It was necessary to bring the hydrophone and geophone to a satisfactory S/N before summation, in order to derive reliable operator for PZ summation. One important point for this 4D project was to favor the less statistical and less adaptive process. Multiple attenuation: in 4D, the multiple can be highly non repeatable because of changing sea water conditions. The area is known for its severe contamination of short period multiples due to shallow-marine, hard sea bottom environment. After PZ summation, an optimized 3D deconvolution was performed. 4D time and amplitude destriping: it was important to remove the distortion due to different acquisition conditions, coupling etc.
Geometry errors in the legacy OBC data: they have negligible impact in 3D but they increase the 4D noise. Significant time was spent correcting these errors.
Noise contamination: the 2C component over the area is highly contaminated by Scholte waves and guided waves. Additionally, the geophone of the monitor data was highly impacted by current noise. It was necessary to bring the hydrophone and geophone to a satisfactory S/N before summation, in order to derive reliable operator for PZ summation. One important point for this 4D project was to favor the less statistical and less adaptive process.
Multiple attenuation: in 4D, the multiple can be highly non repeatable because of changing sea water conditions. The area is known for its severe contamination of short period multiples due to shallow-marine, hard sea bottom environment. After PZ summation, an optimized 3D deconvolution was performed.
4D time and amplitude destriping: it was important to remove the distortion due to different acquisition conditions, coupling etc.
The data integrity analysis and correction, the optimal denoise and demultiple, the careful attention paid to the acquisition-related distortion removal as well as adapted 4D QCS allowed to obtain an interpretable 4D signal which gives useful information about the reservoirs.
These successful results were made possible by a careful control of the noise and multiple attenuation, favoring the use of the deterministic and constrained processes over the adaptive processes even if these latter may be superior in 3D processing; and a robust S/N separation in the 4D crossequalisation/parallel processing were designed and applied. These elements enabled to get an interpretable 4D signal under the very challenging conditions of the considered area and reservoirs.