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If the problem is formation damage, then matrix acidizing may be an appropriate treatment to restore production. This page discusses ways to evaluate whether a well is a good candidate for acidizing. This plugging can be either mechanical or chemical. Mechanical plugging is caused by either introduction of suspended solids in a completion or workover fluid, or dispersion of in-situ fines by incompatible fluids and/or high interstitial velocities. Chemical plugging is caused by mixing incompatible fluids that precipitate solids.
Var Energi has confirmed a discovery at its King and Prince exploration wells in the Balder area in the Southern North Sea. Success at the combined King and Prince exploration wells lifts preliminary estimates of recoverable oil equivalents between 60 and 135 million bbl. King/Prince was drilled in PL 027 by semisubmersible rig Scarabeo 8. The Prince well encountered an oil column of about 35 m in the Triassic Skagerrak formation within good to moderate reservoir sandstones, while the King well discovered a gas column of about 30 m and a light oil column of about 55 m with some thick Paleogene sandstone. An additional King appraisal sidetrack further confirmed a 40-m gas column and an oil column of about 55 m of which about 35 m are formed by thick and massive oil-bearing sandstone with excellent reservoir quality.
Equinor struck oil in Production License 554 with a pair of wells at its Garantiana West prospect. Exploration wells 34/6‑5 S and 34/6-5 ST2 were drilled some 10 km north-east of the Visund field, with the former encountering a total oil column of 86 m in the Cook formation. The latter well encountered sandstones in the Nansen formation, but did not encounter commercial hydrocarbons. Recoverable resources are estimated at between 8 and 23 million BOE. "This is the first Equinor-operated well in the production license, and the fifth discovery on the Norwegian continental shelf this year," said Rune Nedregaard, senior vice president, exploration and production south. "The discovery is in line with our roadmap of exploring near existing infrastructure in order to increase the commerciality."
Interwell tracer tests are widely used. This article reviews some of the studies reported in open literature. The selection introduces different problems that have been addressed, but the original papers should be studied to obtain a more detailed description of the programs. The Snorre field is a giant oil reservoir (sandstone) in the Norwegian sector of the North Sea. Injection water and gas were monitored with tracers, 18 and the resulting tracer measurements are discussed in this page.
The jackup-type mobile offshore drilling unit (MODU) has become the premier bottom-founded drilling unit, displacing submersibles and most platform units. The primary advantage of the jackup design is that it offers a steady and relatively motion-free platform in the drilling position and mobilizes relatively quickly and easily. Although they originally were designed to operate in very shallow water, some newer units, such as the "ultra-harsh environment" Maersk MSC C170-150 MC, are huge (Figure 1) and can be operated in 550 ft in the GOM. This type of unit can be commercially competitive only in the North Sea and in very special situations. Figure 1--Maersk's giant jackup (largest in the world) designed for deepwater use (550 ft in the GOM) and harsh North Sea environment.
If pore volume contraction contributes prominently to overall expansion while the reservoir is saturated, then the reservoir is classified as a compaction drive. Compaction drive oil reservoirs are supplemented by solution gas drive if the reservoir falls below the bubblepoint; they may or may not be supplemented by a water or gas cap drive. Compaction drives characteristically exhibit elevated rock compressibilities, often 10 to 50 times greater than normal. Rock compressibility is called pore volume (PV), or pore, compressibility and is expressed in units of PV change per unit PV per unit pressure change. Rock compressibility is a function of pressure.
Nearly 150 workers have been evacuated or are due for evacuation from Shell's Shearwater project in the North Sea since a COVID-19 outbreak emerged at the end of June, the company said on 20 July, as the industry called for an exemption from self-isolation rules for offshore workers. So far, 26 people at the Shearwater oil and gas hub have tested positive for COVID-19, with another 122 categorized as having been "close contacts" of those infected, Shell told S&P Global Platts. Most have already been flown to shore, with a small number isolating at the facility before returning to shore, Shell said, adding that the spread of infection was slowing, with only five cases detected in the last 7 days of the outbreak. Shearwater is the focus of concerns that rising UK infection rates could spread to the offshore oil and gas sector, which normally provides 1 million B/D of oil including the Brent and Forties benchmark grades and meets about half the country's gas needs. Offshore workforce numbers have recently recovered to well over 10,000, following a steep fall last year in response the pandemic, according to industry figures.
Chevron, Shell, and TotalEnergies are supporting a 12-month research project, which is expected to achieve a world-first in demonstrating high-resolution satellite-based monitoring of anthropogenic methane (CH4) emissions at sea. Led by Canadian-based GHGSat, the new research project aims to assess the feasibility of space-based methane monitoring technology to measure emissions from offshore oil and gas platforms. GHGSat is testing a technique developed by NASA, amongst others, and proven in fields such as ocean height and ice-thickness measurement. With a vantage point 500 km above the Earth, and high revisit rates, the company believes satellites could hold the key to verifying emissions from rigs, easily and cost-effectively. The study will monitor 18 offshore sites in locations such as the North Sea and the Gulf of Mexico for over 12 months.
Odfjell has been awarded a three-well, $40-million drilling contract for its semisubmersible drilling unit Deepsea Stavanger by Equinor. The rig will join sister units Deepsea Atlantic and Deepsea Aberdeen under contract with the Norwegian operator. The rig is scheduled to start drilling the first of three planned exploration wells in the North Sea in February 2022. The wells are expected to take about 4 months to complete. The contract includes continuing options after the initial phase.
An exploration well drilled by Wintershall on its Dvalin North prospect in the Norwegian Sea has encountered a significant gas reservoir. The discovery at Dvalin North is estimated to hold to hold 33–70 million BOE and is just 12 km north of the company's operated Dvalin field and 65 km north of the operated Maria field. The well also encountered hydrocarbons in two shallower secondary targets, with a combined resource estimate of 38–87 million BOE, making the potential for the field in excess of 150 million BOE. The well, drilled by the Deepsea Aberdeen rig, encountered gas, condensate, and oil columns of 33 m and 114 m in the Cretaceous Lysing and Lange formations, respectively. In the primary target in the Garn Formation, the well found a gas column of 85 m.