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A British independent bet its future on proving that fractured basement formations could produce large amounts of oil and gas. Based on its first two wells, the proposition that these highly fractured layers of awful-quality reservoir rock can produce billions of barrels of oil is looking very unlikely, but there might be something of value down there. Last April, Hurricane Energy predicted those two development wells could easily produce 17,000 B/D of oil from rock it said held “half a billion barrels of oil.” Now Hurricane’s ambitious plans and its identity as “basement reservoir specialists” are in tatters. The initial wells were productive but much of what was coming out of the lower one—205/21a-7z—was water.
Edwards, Andrew (Weatherford Completion Systems) | Tuffy, Declan (bp Exploration Ltd.) | Sweeney, Kieran (bp Exploration Ltd.) | Glennie, James (Weatherford Completion Systems) | Babazade, Farrukh (Weatherford Completion Systems) | Robertson, Bruce (Weatherford Completion Systems) | Murdoch, Euan (Weatherford Completion Systems)
This paper will portray the development and deployment of remote-activated sliding sleeve devices commissioned for use in a two-stage completion North Sea project. The sliding sleeves are required within the lower completion to provide access to the reservoir, protection to a control line and act as part of the fluid-loss envelope. Remote activation technology has been implemented to the sleeve designs to improve efficiency and introduce operational flexibility.
Three variants of sleeves were designed and deployed to facilitate well objectives. The first variant is run-in-hole (RIH) Open to provide a circulation path and subsequently closed post displacement activities. The second variant is RIH Closed and is distributed across the reservoir. These sleeves are remotely opened post Xmas tree installation and provide the tubing/annulus communication for production or injection. The third variant is again RIH Closed, but this is a purely mechanical sleeve to allow further access to compartments or different reservoir units later in the well's life. A variant of open-hole anchor with bypass capability was also developed and tested.
Remote-activated sliding sleeves were prototyped and qualified to API 19AC. In addition to the standard requirements of API 19AC, open/close cycles were also performed with lost circulation material-laden (LCM) fluid along with low hydrostatic pressure function testing. This latter testing is to allow for sequential functioning without having to shut in or choke back the well, instead functioning while the well is flowing or even under full operational drawdown. Three wells have been completed to date, two producers and one injector. The RIH Open sleeves have successfully acted as a replacement to a traditional fluid loss valve and the RIH Closed sleeves have allowed zonal isolation, selective water shut-off and reservoir management. The use of open-hole anchors has also been standardised, in producers to support future stimulation operations and in injectors to combat thermal contraction. Across all three wells the RIH Open sleeves have all been actuated successfully via Radio Frequency Identification (RFID) tag carrier or timer and the RIH Closed via pressure sequence and / or timer. The second producer also saw the first implementation of the staged clean-up functionality with sleeves opening at four different intervals over a period of 17 days.
Bahrain oil Field being the first oil discovery in the gulf region in 1932 is now in a mature stage of development. Crestal gas injection in the oil bearing, under saturated, layered and heavily faulted carbonate Mauddud reservoir has continued to be the dominant drive mechanism since 1938. Thirty-eight 40-acre 5-spot waterflood patterns were implemented from 2011 to 2012. These patterns were located in both South East and North West part of Mauddud reservoir with a maximum injection rate of 80 MBWPD. With less than 10% PV water injected as of December 2012, premature water breakthrough was observed in most of the producers. Rapid water breakthrough in Mauddud A (Ba) is attributed to presence of high permeability vugs and layers resulting water cycling and poor sweep in the matrix leaving bypassed oil. Following recommendations from the 2013 partner Peer Assist, the South East and North West waterfloods have been converted from pattern to peripheral with down dip wells providing water injection. Peripheral re-alignment has arrested the production decline, reduced water cut and stabilized the production.
Surveillance data such production logs, reservoir saturation logs, noise logs, temperature and tracer data form the basis of understanding waterflood performance. Additionally, an array of analytical tools were used for diagnosis and analysis. Amongst the diagnostic tools, the Y- function helped to understand water cycling and sweep; the modified-Hall plot helped understand high-permeability channel or lack thereof and water-oil-ratio (WOR) gave the clue on fluid displacement. Additional plots such as "X" plot, hydrocarbon pore volume injected vs. recovery, Jordan plot, Cobb sweep plot, Stagg's plot and decline curve analysis were generated to gain insight on the sweep, recovery and remaining moveable oil of the waterflood.
Based on the waterflood analysis, a field study was initiated in December 2016 by shutting more than 80% of water injection followed by complete shut-in in September 2017. The motivation was to reduce the water cut, improve production taking advantage of gravity drainage effect of gas injectors located up dip of waterflood areas. The implementation of water injection shut-in is still ongoing in the field and pressure/production performance is being closely monitored.
This study underscores the importance of fit-for-purpose surveillance data along with ensemble of modern analytical tools to diagnose and analyze waterflood performance. This understanding also paves the way for much improved learning to take appropriate actions and help devise long-term reservoir management strategy.
Service firms are diversifying their portfolios, in part driven by large-scale budget cuts among operators since the industrywide downturn. Subsea advancements in the works include longer tiebacks, an underwater drone that lives on the seafloor, and a robotic manifold capable of actuating dozens of valves. Do these new capabilities, born of necessity, signal a sea change in industrywide technology development? The biennial SPE Offshore Europe conference will explore a diverse set of topics, including the application of digital technologies and preparing for a low-carbon energy future and ongoing work around standardization and decommissioning. Hurricane Energy is still on pace for first oil in 2019 for the Lancaster field, which may lead to more significant development in the UK North Sea.
Africa (Sub-Sahara) Sonangol's deepwater Orca-1 well encountered oil in the presalt layer of Block 20/11 in the Cuanza basin offshore Angola. The well reached a measured depth of 12,703 ft. Initial well tests saw flow rates of 16.3 MMcm/D of gas and 3,700 BOPD. Cobalt International Energy (40%) is the operator, with partners Sonangol Research and Production (30%) and BP Exploration Angola (30%). Asia Pacific Premier Oil's Kuda Laut-1 well in Indonesia's Tuna production sharing contract has encountered 183 net ft of oil-bearing reservoir and 327 net ft of gas-bearing reservoir. Following evaluation operations, the well will be sidetracked to drill the Singa Laut prospect in an adjacent fault block. Premier is the operator (65%), with partner Mitsui Oil Exploration Company (35%).
Africa (Sub-Sahara) BG Group discovered gas in the Taachui-1 well and sidetrack in Block 1, offshore Tanzania. The drillship Deepsea Metro Idrilled Taachui-1 close to the western boundary of Block 1, then sidetracked the well and drilled to a total depth of 4215 m. The well encountered gas in a single gross column of 289 m within the targeted Cretaceous reservoir interval. Net pay totaled 155 m. Estimates of the mean recoverable gas resources are around 1 Tcf. Statoil (65%) and co-venturer ExxonMobil (35%) made a sixth discovery--the Piri-1 well--in Block 2 offshore Tanzania. Piri-1 was drilled by drillship Discoverer Americas, at a water depth of 2360 m.
Africa (Sub-Sahara) Cairn Energy has flowed oil from its SNE-2 well offshore Senegal. Drillstem testing of a 39-ft interval achieved a maximum stabilized but constrained flow rate of 8,000 B/D of high-quality pay. A flow rate of 1,000 B/D of relatively low-quality pay was achieved from another zone. Drilled to appraise a 2014 discovery, the well lies in the Sangomar Offshore block in 3,937 ft of water 62 miles from shore. Drilling reached the planned total depth of 9,186 ft below sea level. Cairn has a 40% interest in the block with the other interests held by ConocoPhillips (35%), FAR (15%), and Petrosen (10%).
Africa (Sub-Sahara) San Leon Energy reported encouraging performance from its OML 18 field in Nigeria. Reperforation of an oil well increased gross field production to approximately 61,000 B/D before output was temporarily scaled back to 53,000 B/D for a shut-in, upgrade, and workover of the well. A number of other field wells will be reperforated in coming months, the company said. San Leon holds a 9.72% interest in the field, which is operated by Eroton (35%). Nigerian National Petroleum Corp. holds the remaining stake. FAR said that drilling has begun on the SNE-5 appraisal well offshore Senegal. The well and the following SNE-6 well will evaluate the upper SNE reservoir units' connectivity and deliverability by oil flow testing that will include interference tests.
Hurricane Energy reported that it believes the Greater Lancaster Area is a single hydrocarbon accumulation, which would make it the largest undeveloped discovery on the United Kingdom Continental Shelf. Operations on the 205/23-3A Halifax well were complete with the well leading to an oil discovery, the company said. Initial data analysis also indicated that the well is linked to the Lancaster field and forms a single large hydrocarbon accumulation. Preliminary third-party analysis of the well shows a "very significant" hydrocarbon column of at least 3,792 ft within the basement rock and it extends well below the local structural closure, Hurricane said. Following discussions with the UK Oil and Gas Authority, the company said the well has been suspended with future possibilities of deepening and/or further testing.
Siccar Point Energy has concluded well-testing operations on the 204/10a-5 appraisal well in the Cambo field, northwest of Shetland. A vertical pilot hole was initially drilled, confirming over 100 ft of oil column and a higher-than-anticipated net pay of 58 ft. Extensive logging and coring were conducted, confirming a high-quality multi-Darcy reservoir with petrophysical properties better than anticipated. A 1,612‑ft horizontal section was then drilled to conduct an extended well test. Following initial well-cleanup operations, the well was successfully tested on natural flow for 10 days.