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Dai, Chong (Rice University) | Dai, Zhaoyi (Rice University) | Paudyal, Samiridhdi (Rice University) | Ko, Saebom (Rice University) | Zhao, Yue (Rice University) | Wang, Xin (Rice University) | Yao, Xuanzhu (Rice University) | Kan, Amy (Rice University) | Tomson, Mason (Rice University)
Abstract Calcite, as one of the most common scales in oilfield can be inhibited by common scale inhibitors. The measurement of calcite nucleation and inhibition is a challenge, because of the difficulty to control pH as a result of CO2 partitioning in and out of the aqueous phase. A new kinetic turbidity test method was developed so that the partial pressure of CO2, pH, and SI can be precisely controlled. Calcite nucleation and inhibition batch tests were conducted under various conditions (SI = 0.24-2.41, T = 4-175 °C, and pH = 5.5-7.5) in the presence of common phosphonate and polymeric inhibitors. Based on experimental results, calcite nucleation and inhibition semi-empirical models are proposed, and the logarithm of the predicted induction time is in good agreement with the measured induction time. The models are also validated with laboratory and field observations. Furthermore, a new BCC CSTR Inhibition (BCIn) test method that applied the Continuous Stirred Tank Reactor (CSTR) theory has been developed, for the first time. This BCIn method was used for calcite inhibitor screening tests and minimum inhibitor concentration (MIC) estimation. By only running one experiment (< 1 hour) for each inhibitor, BCIn method selected the effective inhibitors among 18 common inhibitors under the conditions of SI = 1.23 at 90 °C and pH = 6. It was also found that the critical concentration (Ccrit) from BCIn method has a correlation with the MIC from batch tests. This study provided a simple and reliable solution for conducting calcite scale inhibition tests in an efficient and low-cost way. Furthermore, the newly developed prediction models can be used as guidance for laboratory tests and field applications, potentially saving enormous amounts of time and money.
The sheer expanse of the deep sea and the technological challenges of working in an extreme environment make these depths difficult to access and study. Scientists know more about the surface of the moon than the deep seafloor. The Monterey Bay Aquarium Research Institute (MBARI) is leveraging advancements in robotic technologies to address this disparity. An autonomous robotic rover, Benthic Rover II, has provided new insight into life on the abyssal seafloor, 4,000 m beneath the surface of the ocean. A study published in Science Robotics details the development and proven long-term operation of this rover.
Waste Not … Clean Energy Fuels and BP announced that their renewable natural gas (RNG) joint venture will build on previously announced plans to finance and develop new projects at dairy farms, starting in the Midwest. Located in South Dakota and Iowa, the dairy farms, with more than 30,000 cows, have the estimated potential to convert the methane produced from waste into more than 7 million gallons of RNG annually. Agriculture accounts for nearly 10% of US greenhouse-gas (GHG) emissions, according to the US Environmental Protection Agency, and the idea is that capturing methane from farm waste can lower these emissions. RNG is used as a transportation fuel and has lower GHG emissions on lifecycle basis when compared with conventional gasoline and diesel. The California Air Resources Board has given similar projects a carbon intensity (CI) score of weighted average of 320 compared with CI scores of 101 for conventional diesel fuel and 15 for electric batteries.
Amber Sparks is a marine environmental scientist and oil and gas consultant. She is a cofounder of Blue Latitudes. Sparks specializes in ecological impact assessments, marine biological monitoring, and habitat restoration through the lens of the Rigs to Reefs program. Her work is primarily centered around the ecological, economic, and social issues surrounding the implementation of Rigs to Reefs decommissioning option in California and internationally. Sparks holds a BA in marine science from UC Berkeley and a MAS in marine biodiversity and conservation from Scripps Institution of Oceanography. In 2018, she was recognized on Forbes 30 Under 30 list in the energy sector for her work with Blue Latitudes.
California's oil and gas regulator on 21 October proposed that the state ban new oil drilling within 3,200 ft of schools, homes, and hospitals to protect public health in what would be the nation's largest buffer zone between oil wells and communities. It's the latest effort by Democratic governor Gavin Newsom's administration to wind down oil production in California, aligning him with environmental advocates pushing to curb the effects of climate change and against the powerful oil industry in the nation's seventh-largest oil-producing state. State officials called it one of the most aggressive steps in the nation, and perhaps the world, to protect public health and safety from the dangers of oil and gas drilling. More than 2 million Californians live within 3,200 ft of oil drilling sites, primarily in Los Angeles County and the Central Valley. "Extracting oil is a dirty business, and it's had a real impact on Californians," said Jared Blumenfeld, California's secretary for environmental protection.
Summary Managed pressure drilling (MPD) is a form of drilling that allows greater and more precise wellbore pressure control than conventional drilling. In addition, the mud weight used will be lower than for the conventional mud weight, and a secondary choke or frictional pressure will be applied on the surface to create a combined annular pressure profile within the well. For this paper, we investigated the effect of high power fiber laser heat tension on the carbonate rock body of the Kangan Formation during the irradiation process with accurate simulation work and by comparing the model with experimental results. First, the enforced stress by heat from the laser source was analyzed, and then the fracture propagation pattern in the rock body throughout the entire irradiation process was obtained. This research presented the weakening and fracturing mechanism that was generated from heat exposure during laser irradiation and determined numerical results for fracture pressure before and after laser irradiation. Also, MPD as an effective technology to control this induced anomaly was proposed during the laser-assisted drilling (LAD) operation to prevent any loss, gain, hole instability, or other drilling problem related to this fracturing and weakening.
Singh, A. (Stanford University, Stanford, Now at ResFrac Corporation) | Zoback, M. D. (Stanford University, Stanford) | Xu, S. (Stanford University, Stanford, Now at Research Institute of Petroleum Exploration and Development, Beijing)
ABSTRACT: Variations of minimum horizontal stress (Shmin) with depth and geological layering are observed frequently in unconventional hydrocarbon reservoirs through field stress measurements. In this study, we show that these variations can be predicted by laboratory creep experiments performed on rock samples from representative geological layers utilizing the concept of viscoelastic stress relaxation. We present a modified viscoelastic stress relaxation power law framework that can be applied for normal and strike-slip faulting environments and show its application to a case study in a prolific unconventional oil & gas formation located in the northeastern United States. We utilize viscoelastic power law parameters measured through laboratory creep experiments to compute a discrete 1-D Shmin profile at depths corresponding to the rock samples. The computed Shmin values are validated with field measurements conducted at the same depths and show that the laboratory measured creep parameters can be used to accurately predict field scale 1-D stress variations in unconventional reservoir formations. Finally, we show through offset stress measurements and microseismic data that the 1-D stress profile can be applicable over large spatial scales if there is continuity in the lithological layering.
Abstract Drill sequence optimization is a common challenge faced in the oil and gas industry and yet it cannot be solved efficiently by existing optimization methods due to its unique features and constraints. For many fields, the drill queue is currently designed manually based on engineering heuristics. In this paper, a heuristic priority function is combined with traditional optimizers to boost the optimization efficiency at a lower computational cost to speed up the decision-making process. The heuristic priority function is constructed to map the individual well properties such as well index and inter-well distance to the well priority values. As the name indicates, wells with higher priority values will be drilled earlier in the queue. The heuristic priority function is a comprehensive metric of inter-well communication & displacement efficiency. For example, injectors with fast support to producers or producers with a better chance to drain the unswept region tend to have high scores. It contains components that weigh the different properties of a well. These components are then optimized during the optimization process to generate the beneficial drill sequences. Embedded with reservoir engineering heuristics, the priority function helps the optimizer focus on exploring scenarios with promising outcomes. The proposed heuristic priority function, combined with the Genetic Algorithm (GA), has been tested through drill sequence optimization problems for the Brugge field and Olympus field. Optimizations that are directly performed on the drill sequence are employed as reference cases. Different continu- ous/categorical parameterization schemes and various forms of heuristic priority functions are also investigated. Our exploration reveals that the heuristic priority function including well type, constraints, well index, distance to existing wells, and adjacent oil in place yields the best outcome. The proposed approach was able to achieve a better optimization starting point (∼5-18% improvement due to more reasonable drill sequence rather than random guess), a faster convergence rate (results stabilized at 12 vs. 30 iterations), and a lower computational cost (150-250 vs. 1,300 runs to achieve the same NPV) over the reference methods. Similar performance improvement was also observed in another application to a North Sea type reservoir. This demonstrated the general applicability of the proposed method. The employment of the heuristic priority function improves the efficiency and reliability of drill sequence optimization compared to the traditional methods that directly optimize the sequence. It can be easily embedded in either commercial or research simulators as an independent module. In addition, it is also an automatic process that fits well with iterative optimization algorithms.
With an increasing emphasis on emission restrictions and environmental impact of carbon-based energies, transportation industries are rapidly focusing on research, development, and implementation of zero-emission fuels and technologies. In the United States, the maritime industry provides key transportation services for people and goods. Immediate and future legislation at the state and federal levels are beginning to push passenger vessel operators to seek more carbon-neutral propulsion methods and begin the necessary transition towards a zero-emission future. Small high-speed, zero-emission vessel concepts are being introduced in the United States, most notably the SWITCH project of San Francisco. The SWITCH project aims to put the first hydrogen fuel cell e-ferry into service in 2021. To date, the zero-emission fast ferry efforts have focused on smaller passenger vessels. This paper examines the potential design elements and operating conditions required for a large (450 passengers) high-speed vessel to meet zero-emission standards. Key ferry metrics of speed and passenger capacity are studied with this concept hull to compare a zero-emission propulsion system against a more traditional carbon-based system. To account for major project decision factors, the economics/cost and regulatory restrictions of a hydrogen fuel cell system are considered for a high-speed passenger vessel of this scope. A sensitivity analysis is performed to determine the technological and performance gains necessary for fuel cell power to match the current capabilities of carbon-based powers. Future development of zero-emission technologies is discussed to evaluate the continually improving opportunities for such a large high-speed vessel.