Gas City, United States
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Wallace K.J.,Encana Oil and Gas United States Inc. | Reyes Aguirre P.,Schlumberger | Jinks E.,Encana Oil and Gas United States Inc. | Yotter T.H.,Encana Oil and Gas United States Inc. | And 2 more authors.
Society of Petroleum Engineers - SPE Hydraulic Fracturing Technology Conference, HFTC 2016 | Year: 2016

This paper describes a comprehensive field study of eight horizontal wells deployed in the stacked Niobrara and Codell reservoirs in the Wattenberg oilfield (Denver-Julesburg basin). The overall goal was to understand the geometry of the hydraulic fractures (propped), producing volume with respect to completions design, target reservoirs, and well spacing. Through this understanding we are able to develop the asset more effectively and economically. In this study, an unconventional hydraulic fracture model was developed and calibrated against surface and downhole microseismic recordings, fifrac hits in offset vertical wells, chemical tracers, pressure interference testing, diagnostic fracture injection tests (DFITs), and treatment pressure/instantaneous shut-in pressure (ISIP) history matching. The hydraulic fracture geometry and conductivity were simulated using unconventional models populated with a natural discrete fracture network (DFN) defined through outcrop and image log observations along with a rigorous mechanical earth model. A special unstructured grid that conforms to the shape of the calibrated hydraulic fracture model planes was constructed. This unstructured, fractured reservoir grid was fed into a compositional reservoir simulator that was tuned using pressure dependent permeability, offset vertical well pressure depletion, and relative permeability (among others) to match the production history available to date. This workflow allowed for complete integration of geological, geomechanical, and production models in a single platform to produce a consistent set of results. This study concludes that 1) Increasing the hydraulic fracture treatment volume beyond a certain point does not significantly enhance the fracture geometry or improve early time well performance; 2) additional wells are needed to access undrained reservoir; 3) existing vertical-well depletion has a significant impact on early time well performance, and; 4) hydraulic fracture height extension allows initial communication between the Niobrara and Codell reservoirs, however this connectivity dissipates during production likely due to the loss of fracture connectivity vertically. Copyright 2016, Society of Petroleum Engineers.


Johnson J.,Encana Oil and Gas United States Inc. | Turner M.,Encana Oil and Gas United States Inc. | Rhein T.,Petrohawk Energy
Oilfield Review | Year: 2011

The goal of a hydraulic fracturing treatment is to improve well productivity by creating a flow path from the formation to the wellbore.Conventional fracturing treatments fill the fracture completely with proppant, which holds the fracture open to preserve the production pathway.A new hydraulic fracturing technique crectes a network of open channels throughout the proppant pack, improving fracture conductivity by orders of magnitude.Performing this technique has significantly improved the economic viability of wells in several producing fields. Copyright © 2011 Schlumberger.


Fichter J.,Encana Oil and Gas United States Inc. | Wunch K.,Baker Hughes Inc. | Moore R.,Encana Oil and Gas United States Inc. | Summer E.,Hopes Creek | And 2 more authors.
NACE - International Corrosion Conference Series | Year: 2012

Bacterial contamination from drilling and fracturing can lead to serious problems in unconventional oil and gas shale plays. Large water volumes for these processes are transported from aquifers, municipal waters, rivers, lakes, ponds or oilfield flowback water to the wellsite and stored in frac tanks or earthen impoundments. Typically, these waters are contaminated with bacteria. Furthermore, fracturing fluids contain gelling agents or polyacrylamide-based friction reducers which are readily available bacterial food sources. If these fluids are insufficiently treated, establishment of sulfate-reducing bacteria (SRB) and acid-producing bacteria (APB) can lead to operational issues including: 1) biogenic sulfide production and formation souring, 2) plugging from iron sulfide scale production, 3) microbially influenced corrosion (MIC), and 4) premature degradation of fracturing fluids. As operators have moved into hotter, deeper unconventional shale plays, the following question has been posed: "How hot is too hot for bacteria?" Downhole reservoir temperatures can approach 260 to 360°F (127 to 182°C), temperatures previously thought to be inhibitory to bacteria. Are introduced bacterial species capable of becoming established in these hot reservoirs following the drilling and fracturing processes? Does the nutrient influx from drilling and fracturing processes stimulate viable, indigenous bacteria? These are some of the key questions addressed in this study.


Gale B.R.,Encana Oil and Gas United States Inc. | Trostel M.V.,Encana Oil and Gas United States Inc. | Armitage D.L.,Cartasite | Mason M.A.,Cartasite | Bautista L.S.,Cartasite
Proceedings - SPE Annual Technical Conference and Exhibition | Year: 2011

Over 40% of all injuries and fatalities in the oil and gas industry are attributed to vehicular operations. Additionally, nearly one third of all fatalities were due to highway motor vehicle crashes as reported in a study of deaths in the industry between 2003-2008 (Retzer, et. al, NIOSH, 2011). For years the industry has tried a myriad of strategies to influence behavior, yet the risk of motor vehicle incidents (MVI's) remains a challenge for the industry and remains at the top of the list of hazards. The proliferation of inexpensive sensors and wireless networks presented an opportunity to measure subtle patterns of human behavior that might be leading indicators of a driver's crash risk. Several years ago, Encana Oil & Gas (USA) Inc. (Encana) and a Denver based technology firm, Cartasite, teamed up to study driver behavior. The goals of this research were twofold: ⊙ profile the patterns of individuals against a large population of drivers, and ⊙ attempt to influence those patterns to reduce risk, fuel consumption, and emissions. The yearlong study program produced encouraging results and after analyzing the data, the decision was made to move forward with commercial product development. Encana has now deployed this technology on its entire fleet for over a year. A new Driving Safety Program has been put in place at Encana to effectively leverage the insights and data being collected. The impact of Encana's Driving Safety Program, presented herein, are encouraging and suggest that corporations may well be able to significantly reduce motor vehicle incidents and increase safety for field workers. Copyright 2011, Society of Petroleum Engineers.


Raymond J.,Dow Microbial Control | Parnell E.,Baker Hughes Inc. | Fichter J.,Encana Oil and Gas United States Inc.
NACE - International Corrosion Conference Series | Year: 2014

Conventional antimicrobial treatments for hydraulic fracturing fluids, flow-back water, and produced water include chemistries such as glutaraldehyde, tetrakis-(hydroxymethyl)-phosphonium sulfate (THPS), and quaternary ammonium compounds (quats). While the rapid microbial kill efficacy of these biocides in top-side water sources are effectively demonstrated by traditional microbial enumeration methodologies, such as "bug-bottles", the long-term potential for protection of the oil and gas reservoirs from microbial-induced damage has received limited attention. A stringent two-stage laboratory method has been developed to assess rapid and long-term biocide efficacy, ranging from the mild, top-side conditions of water sources in drilling and fracturing operations to the harsh conditions of downhole environments. Specifically, water sources used in stimulation and fracturing operations were treated with various concentrations of biocide combinations and incubated at elevated temperatures during the course of the laboratory experimental procedure. At predetermined time points during the two-month test, the heat-aged samples were challenged with oil and gas field microbial contaminants (acidproducing and sulfate-reducing bacteria) to evaluate extended biocide performance in water chemistries and temperatures that mimicked downhole environments. This paper discusses a summary of effective biocide treatments for the holistic protection of hydraulic fracturing operations from microbial contamination. © 2014 by NACE International.


Golikeri S.V.,IPSI LLC | Yu J.,IPSI LLC | Lee G.,IPSI LLC | Elliot D.,IPSI LLC | And 3 more authors.
GPA Annual Convention Proceedings | Year: 2011

Encana Oil and Gas has completed an evaluation of retrofit options to increase the capacity and recovery levels at their Fort Lupton facilities. The stripping gas option uses about 18% less horsepower than that for the conventional retrofit option. The evaluation and selection of a proprietary Stripping Gas Refrigeration scheme that produces a 20% increase in capacity and 38% increase of ethane recovery without the addition of residue gas compression and/or propane refrigeration is discussed. This is an abstract of a paper presented at the 90th Annual Convention of the GPA (San Antonio, TX 4/3-6/2011).


Gierlowski-Kordesch E.H.,Ohio University | Gierlowski-Kordesch E.H.,Encana Oil and Gas United States Inc. | Cassle C.F.,Ohio University | Cassle C.F.,Encana Oil and Gas United States Inc.
Earth-Science Reviews | Year: 2015

'Spirorbis' worm tubes, described from the geologic record spanning the Silurian through the Middle Jurassic, have been assigned freshwater to brackish to marine affinities. Now interpreted as phoronid worm tubes of microconchid origin, the true paleoenvironment (i.e. paleosalinity) for these tubeworms can be determined with a detailed study of their distribution with respect to local sedimentology as well as with recognition of their biologic characteristics to determine their ability to osmoregulate. Osmoregulation is a key characteristic in determining the ability of a marine body type to tolerate freshwater. The literature on over three hundred localities worldwide covering Phanerozoic lacustrine sites and Paleozoic to Lower Triassic marine-influenced sites were searched and those containing microconchid fossils ranging from "freshwater to marine" were documented; data collection included presence or absence of these worm tubes, their preservation mode as transported or in life position, and their associated fauna and flora along with paleoenvironmental interpretation. These worm tubes are not documented from any purely freshwater continental paleoenvironment unconnected to the ocean. All fossil occurrences of these microconchid tubes are in association with coastlines, whether within a nonmarine-marine transition (tidal coast, estuary, delta) or a distal transition floodplain within a low-gradient coastal area potentially affected by rare storm surges or tsunamis. The biology of this organism supports a marine affinity because of its and its sister phylum Brachiopoda need for osmoregulation within marine salinities only. Opportunistic settling on hard substrates or plants and the growth of a shell occurring within an hour during larval settlement are similar to modern spirorbid polychaete worms. The '. Spirorbis' problem of multiple life habitats is solved: microconchid worm larvae can settle anywhere where currents exist along a coastline and as far inland as storm surges can go, but they only thrive within true marine conditions and are not freshwater fauna. Microconchid worm tubes preserved within continental settings indicate marine influence only, not living habitats. © 2015 Elsevier B.V.


Mitchell R.F.,Halliburton Co. | Sweatman R.,Encana Oil and Gas United States Inc. | Young G.,Encana Oil and Gas United States Inc.
SPE/IADC Drilling Conference, Proceedings | Year: 2013

This paper describes thermal modeling and its combination with drilling fluid analysis to reveal concealed changes in well conditions during various drilling and completion operations. These hidden conditions represent significant changes in the well's drilling and completion fluid temperature, pressure, and density (FTPD) that may help explain wellbore stability and integrity issues. For example, the model results may allow operators to look for FTPD-related wellbore stability issues where the hole is not circulated and is static for many hours. Deeper wells and those with greater differences between induced and natural temperature and pressure conditions may have dangerous conversions of pressure over-balances into under-balances that can cause pore fluid influx, cross-flow, collapse, and other severe wellbore failures. Long, deep holes that are being circulated may also be modeled to look for FTPD-related issues not revealed by other means. Conditions such as over-balanced pressure and stable rock conditions may actually change to under-balanced pressure and unstable rock conditions with consequences including kicks, solids beds from formation breakouts, flow after cementing, stuck pipe by hole collapse, salt creep acceleration, etc. A case history is discussed where the prototype model correctly predicted that no formation gas influx would occur during a long static period. A nearby well with similar open-hole conditions experienced a blowout during the same static time period. A comparison of the well's annular pressure measurements to the model's predictions indicated that the pressure changes were thermally induced and were not from a formation pore-pressure source. When the annular pressures subsided as predicted, no gas was found in the annulus. Studies will continue to test the FTPD model in different types of wells, well conditions, and applications for drilling and completion operations, and the prototype model may be modified accordingly. Copyright 2013, SPE/IADC Drilling Conference and Exhibition.


Kulmann J.,Encana Oil and Gas United States Inc. | Herbert C.K.,Encana Oil and Gas United States Inc.
GPA Annual Convention Proceedings | Year: 2011

As the oil and gas industry works more and more with electrical components and with equipment that requires electricity, attention has become more focused on how to train personnel and how to keep workers safe from electrical hazards. A discussion covers some of the hazards of electricity specific to the oil and gas industry; some electrical safety best practices; awareness of arc flash; ways to prevent or mitigate the risk associated with arc flash; and basic requirements of an electrical safety program to be in compliance with industry accepted practices. This is an abstract of a paper presented at the 90th Annual Convention of the GPA (San Antonio, TX 4/3-6/2011).


Williams-Stroud S.C.,MicroSeismic Inc. | Barker W.B.,MicroSeismic Inc. | Smith K.L.,Encana Oil and Gas United States Inc.
73rd European Association of Geoscientists and Engineers Conference and Exhibition 2011: Unconventional Resources and the Role of Technology. Incorporating SPE EUROPEC 2011 | Year: 2011

Microseismic activity was monitored during stimulation of a horizontal well in a tight gas shale using a wide-aperture array of geophones deployed on the surface above the well location. The lateral was drilled perpendicular to the presumed maximum horizontal stress direction, but long, linear, well-constrained microseismic event trends developed at an angle to the wellbore. Source mechanisms of the events show the failure planes of the events were parallel to the microseismicity trends. However, in-situ stress analysis from a crossed-dipole shear log acquired in the well showed the event trends are not parallel to the maximum horizontal stress direction. This result has important implications for stress interpreted from source mechanism analysis and for the impact of natural fractures on the stimulation treatment. Prior knowledge of existing fractures in the reservoir may be critically important for deciding the deviation of horizontal wellbores in order to optimize the stimulation treatment and placement of subsequent wells for field development.

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