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The most reliable way to determine stress orientation is to identify features (either geological features or wellbore failures) the orientation of which is controlled by the orientations of the present-day in-situ stresses. Other methods that rely on observing the effect of stress on rock properties using oriented core have been found to be less reliable and subject to influence by factors other than in-situ stress. As previously discussed, wellbore breakouts occur in vertical wells at the azimuth of SHmin, and drilling-induced tensile failures occur 90 to breakouts at the azimuth of SHmax. Therefore, the orientations of these stress-induced wellbore failures uniquely define the orientations of the far-field horizontal stresses when using data from vertical wells. This is true for breakouts whether they are detected using 4-arm- or 6-arm-oriented caliper logs or using electrical or acoustic images, whether obtained by wireline or logging while drilling (LWD) tools.
A leading cause of unsuccessful acid treatment is failure to contact all the damage with the acid. Fluids pumped into a formation preferentially take the path of least resistance. This makes the placement and coverage of the acid an important component of the treatment design. In a typical treatment, most acid enters the formation through the least damaged perforation tunnels, as the schematic in Figure 1 shows. When this happens, it can be readily concluded that acidizing does not work well and is expensive.
The 58,000-ton Argos production platform destined for BP's Mad Dog Phase 2 development in the deepwater US Gulf has sailed from its construction site in South Korea. The semisubmersible was built by Samsung Heavy Industries and was loaded onto a Boskalis heavy-transport vessel at the yard during the last week in January. BP chief Bernard Looney recently praised the Mad Dog Phase 2 project as a testament to the operator's ability to drive costs out of historically costly endeavors. Original budget estimates for Mad Dog Phase 2 ranged upwards of $20 billion, however BP and its partners were able to bring the tab down to $9 billion through simplification and standardization of Argos' design. The project is expected on stream in late 2021.
Shell said it will be adding up to $4.5 billion more in writedowns this year due to issues related to continued low oil and gas prices and disappointing results from a major deepwater development in the Gulf of Mexico. On a day when oil prices dropped on a resurgence of worries about another economic hit due to responses to a surge in COVID-19 cases, Shell's prediction that it was pushing up its write downs by $3.5 to 4.5 billion to near $22 billion was in keeping with the mood swing that follows a month-long-rally. Shell said its adjusted upstream earnings would be negative for the fourth quarter due to the asset valuations reductions. Its production was reduced by a string of recent hurricanes in the Gulf of Mexico and weak demand meant for products, which also meant refineries were running at low levels. One item that stood out on the list featuring onerous contracts and tax credit issues, was a reduction in the value of its Appomattox platform, which is operated by Shell in partnership with CNOOC, which holds a 21% stake.
This marks the first of two Formation Evaluation features for 2021. This topic, along with EOR Operations and Artificial Lift, had such a high number of devoted conference papers, and a high degree of reader interest, that it was expanded and will appear in the August issue as well. The papers chosen by reviewer Rahul Dastidar explore innovative approaches developed by authors of SPE conference papers toward avoiding data bias, working around the absence of openhole data, and reducing the uncertainty of mass-transport complexes. The authors discuss two quality-control approaches that are not meant to replace linearly inverted T2 distributions but which can optimize NMR measurements in real time. The next paper outlines important experience gained in two tight gas fields offshore the UAE for which openhole data were not available for purposes of petrophysical evaluation.
Enbridge is looking to restart operations on its Garden Banks pipeline in the Gulf of Mexico (GOM) as soon as communications are restored following damage from Hurricane Laura in late August. The company declared force majeure on the Garden Banks and the Nautilus lines after inspecting the facilities, but only the Nautilus has started back up. The posted end date for the Garden Bank notice is listed as 26 November. The 1 Bcf/D Garden Banks pipeline extends from Garden Banks Block 128 to South Marsh Island Block 76, where it interconnects with four existing interstate pipelines to move gas onshore. The pipeline also connects the Auger, Enchilada, Baldpate South Marsh Island, and the Magnolia platforms.
Drilling engineers who mine the earth for petroleum and mineral resources may be plying their trade on the Moon, asteroids, and Mars sooner rather than later. This is not a remake of the 1998 Hollywood movie, "Armageddon," in which Bruce Willis leads a ragtag team of oilfield drillers into space to detonate a Texas-size asteroid before it collides with the earth. The European Space Agency (ESA) is partnering with Russia's Roscosmos and private industry to land an ESA-designed robotic drill and laboratory in 2025 to collect and process volatiles (elements and compounds that vaporize in a vacuum) from regolith at the lunar south pole. The project supports the aim of NASA's 2024 mission to land astronauts in the same lunar region to survey the site of the future Artemis Base Camp which will require not only the oxygen that ESA and Roscosmos hope to exploit, but water as well. Regolith is the loose unconsolidated rock and dust that sits atop a layer of bedrock.
This commentary has been prepared by the SPE Reservoir Advisory Committee (RAC) to provide high-level insights for the discussion on the potential consequences of long-term shut-ins on conventional and unconventional reservoirs. The RAC comprises 61 subject matter experts (SMEs) covering the domain of reservoir technical discipline. The views presented in the commentary are the opinions of the SMEs and do not constitute an official position of the SPE on the subject matter. From a completions, production, and facilities perspective, there are significant, and potentially devastating, effects for the long-term shut-ins of wells. Everything we leave in the well and the surface facilities will be subject to corrosion, deterioration, and other chemical/mechanical effects. Perforations and the well itself may become plugged and deformed and the pumps and bottomhole assemblies may be rendered dysfunctional due to the settlement of sand and other debris/contaminants. Moreover, scale buildup and wax and asphaltene precipitation in and around the wellbore are well-known potential problems during shut-ins. The oil and gas industry has a very long history of well surveillance, well maintenance, and well remediation--but as an induction, we have not had any circumstances on the scale of the current situation.
In efforts to preserve cash and repair busted balance sheets in reaction to depressed prices, companies are continuing to withdraw capital and curtail investments worldwide. Oil and gas companies are selling off assets with recoverable reserves of more than 5 billion bbl of liquids and 7.5 billion BOED of natural gas, Rystad Energy estimates. While some divestments were announced before the COVID-19 crash, more were added in its aftermath. The research and consultancy group examined divestment opportunities announced since the fourth quarter of 2019 that exclude unconventional and US onshore assets. An estimated 104,000 square miles of exploration acreage, including potential exploration license sales, are also up for grabs by majors, E&Ps, industrial companies, and integrated companies.