Browsing by Subject "Deepwater"

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Characterizing transitional flow deposits in the proximal Brushy Canyon Formation, Texas
(2015-12) Ustipak, Kelsi Rae; Mohrig, David; Milliken, Kitty; Ponten, Anna; Steel, Ronald
Transitional flow deposits are identified, characterized, and placed in a stratigraphic context in the proximal Brushy Canyon Formation, Guadalupe Mountains, Texas. Transitional flows are sand-laden, mud-rich sediment gravity flows that deposit matrix-rich sandstones that are laterally equivalent to matrix-poor sandstones in deepwater lobe environments. Understanding spatial variability in deepwater facies and developing correct process models based on outcrop studies facilitates accurate predictive drilling and exploration in deepwater hydrocarbon reservoirs. In this study, two well-known outcrops of the Brushy Canyon Formation are investigated with high-resolution data sets of detailed stratigraphic sections, grain size analysis, and thin sections. Results of the study reveal that transitional flow deposits have grain size trends and lateral bed thickness trends that distinguish them from the deposits of other sediment gravity flows.
Controls on mixed carbonate-siliciclastic slope and basinal depositional architecture
(2022-05-10) Price, Buddy James; Janson, Xavier; Kerans, C. (Charles), 1954-; Mohrig, David; Covault, Jacob; Eberli, Gregor P
Deepwater carbonate depositional systems represent historically understudied environments. The Permian Basin provides an advantageous location to re-evaluate these settings due to subsurface data density as well as existing outcrop and subsurface studies providing a framework on which to expand. Regional well log mapping coupled with cores and seismic data highlight a range of carbonate accumulations along the slopes and in the deeper basin indicating a need for updates to current Permian Basin basinal depositional models. Thickness maps and cross sections highlight multiple mounded and elongate carbonate-mud rich accumulations along the western slopes of the Delaware Basin. The mounded nature, lack of platform focused sourcing, and presence of oblique cross-cutting channels suggest these features represent carbonate contourite drifts as opposed to gravity-driven deposits. The drifts extend from the slopes at specific locations corresponding to bathymetric irregularities that likely locally weakened currents, causing deposition. Drift accumulations significantly alter slope geometries but present only one control on slope variation. Additionally, underlying carbonate buildups generates antecedent topography and drives differential compaction which influences platform to basin relief, subsequent slope gradients, and progradation-aggradation ratios. Bottom currents may also locally sweep sediments from toe-of-slope environments, inhibiting progradation. In the deeper basin, mapping highlights previously undocumented calciclastic submarine fans. The fans appear to be point sourced from the platform by antecedent topography, slope reentrants, and regional faults. Some fans extend into the basin over 100km and reach 250m in thickness. The fans range in composition, containing both carbonate debrites and turbidites, and varying volumes of mud-rich siliciclastic turbidites. Runout of gravity flows resulted in concentration of comparatively coarser carbonate material in proximal fan environments and finer siliciclastic mudstone, siltstone, and organic matter in fan fringe environments. This work highlights the first recognition of a carbonate drift system and the expanded interpretation of large-scale calciclastic submarine fans in the Permian Basin. As the Permian Basin represents one of the most heavily studied and geologic data-rich areas in the world, new interpretations of carbonate drift systems and calciclastic submarine fans indicate these systems are likely more common and overlooked in the ancient rock record.
Deepwater ventures : organizing for Gulf of Mexico well construction operations
(2010-12) Hernandez, Carlos Alberto, 1983-; Lewis, Kyle, 1961-; McCann, Bruce
Deepwater Gulf of Mexico well construction operations are some of the most challenging and expensive operations in the E&P industry; not only does the outer continental shelf of the Gulf of Mexico present the distinct environmental challenges of hurricanes and loop currents, its geologic profiles can include such challenges as salt, tar or pressurized zones. To overcome these challenges technology is being pushed to its operational and mechanical limits but technology advances can only accomplish so much without the presence of capable personnel. In the E&P industry, human resources are becoming more limited due to the “Big Crew Change”; a disproportionate relief of the retiring Baby Boomers by Generation X workforce that now requires Generation Y assistance. Regardless of the aforementioned, operators venture out into deepwater with hopes to capitalize on the recently discovered attractive development and exploratory opportunities, but to do so they must organize and properly develop their internal well construction organization in a manner that all members are capable to address the challenges as they come. Therefore, team organization is an operator’s priority, a challenge that should be addressed through common project management practices. This paper parallels the project management practices to establish the appropriate organizational structure for an operator’s deepwater well construction group, manage the human resources to properly delineate responsibilities and to structure their staff management processes to acquire, develop and manage personnel in a manner scalable with the operator’s expansion agenda.
Improved regulatory oversight using real-time data monitoring technologies in the wake of Macondo
(2014-08) Carter, Kyle Michael; Van Oort, Eric
As shown by the Macondo blowout, a deepwater well control event can result in loss of life, harm to the environment, and significant damage to company and industry reputation. Consistent adherence to safety regulations is a recurring issue in deepwater well construction. The two federal entities responsible for offshore U.S. safety regulation are the Department of the Interior’s Bureau of Safety and Environmental Enforcement (BSEE) and the U.S. Coast Guard (USCG), with regulatory authorities that span well planning, drilling, completions, emergency evacuation, environmental response, etc. With such a wide range of rules these agencies are responsible for, safety compliance cannot be comprehensively verified with the current infrequency of on-site inspections. Offshore regulation and operational safety could be greatly improved through continuous remote real-time data monitoring. Many government agencies have adopted monitoring regimes dependent on real-time data for improved oversight (e.g. NASA Mission Control, USGS Earthquake Early Warning System, USCG Vessel Traffic Services, etc.). Appropriately, real-time data monitoring was either re-developed or introduced in the wake of catastrophic events within those sectors (e.g. Challenger, tsunamis, Exxon Valdez, etc.). Over recent decades, oil and gas operators have developed Real-Time Operations Centers (RTOCs) for continuous, pro-active operations oversight and remote interaction with on-site personnel. Commonly seen as collaborative hubs, RTOCs provide a central conduit for shared knowledge, experience, and improved decision-making, thus optimizing performance, reducing operational risk, and improving safety. In particular, RTOCs have been useful in identifying and mitigating potential well construction incidents that could have resulted in significant non-productive time and trouble cost. In this thesis, a comprehensive set of recommendations is made to BSEE and USCG to expand and improve their regulatory oversight activities through remote real-time data monitoring and application of emerging real-time technologies that aid in data acquisition and performance optimization for improved safety. Data sets and tools necessary for regulators to effectively monitor and regulate deepwater operations (Gulf of Mexico, Arctic, etc.) on a continuous basis are identified. Data from actual GOM field cases are used to support the recommendations. In addition, the case is made for the regulator to build a collaborative foundation with deepwater operators, academia and other stakeholders, through the employment of state-of-the-art knowledge management tools and techniques. This will allow the regulator to do “more with less”, in order to address the fast pace of activity expansion and technology adoption in deepwater well construction, while maximizing corporate knowledge and retention. Knowledge management provides a connection that can foster a truly collaborative relationship between regulators, industry, and non-governmental organizations with a common goal of safety assurance and without confusing lines of authority or responsibility. This solves several key issues for regulators with respect to having access to experience and technical know-how, by leveraging industry experts who would not normally have been inaccessible. On implementation of the proposed real-time and knowledge management technologies and workflows, a phased approach is advocated to be carried out under the auspices of the Center for Offshore Safety (COS) and/or the Offshore Energy Safety Institute (OESI). Academia can play an important role, particularly in early phases of the program, as a neutral playing ground where tools, techniques and workflows can be tried and tested before wider adoption takes place.
Regional character of the lower Tuscaloosa formation depositional systems and trends in reservoir quality
(2012-12) Woolf, Kurtus Steven; Wood, Lesli J.
For decades the Upper Cretaceous Lower Tuscaloosa Formation of the U.S. Gulf Coast has been considered an onshore hydrocarbon play with no equivalent offshore deposits. A better understanding of the Lower Tuscaloosa sequence stratigraphic and paleogeographic framework, source-to-sink depositional environments, magnitude of fluvial systems, regional trends in reservoir quality, and structural influences on its deposition along with newly acquired data from offshore wells has changed this decades-long paradigm of the Lower Tuscaloosa as simply an onshore play. The mid-Cenomanian unconformity, underlying the Lower Tuscaloosa, formed an extensive regional network of incised valleys. This incision and accompanying low accommodation allowed for sediment bypass and deposition of over 330 m thick gravity-driven sand-rich deposits over 400 km from their equivalent shelf edge. Subsequently a transgressive systems tract comprised of four fluvial sequences in the Lower Tuscaloosa Massive sand and an overlying estuarine sequence (Stringer sand) filled the incised valleys. Both wave- and tide-dominated deltaic facies of the Lower Tuscaloosa are located at the mouths of incised valleys proximal to the shelf edge. Deltaic and estuarine depositional environments were interpreted from impoverished trace fossil suites of the Cruziana Ichnofacies and detailed sedimentological observations. The location and trend of valleys are controlled by basement structures. Lower Tuscaloosa rivers were 3.8m – 7.8m deep and 145m – 721m wide comparable to the Siwalik Group outcrop and the modern Missouri River. These systems were capable of transporting large amounts of sediment indicating the Lower Tuscaloosa was capable of transporting large amounts of sediments to the shelf edge for resedimentation into the deep offshore. Anomalously high porosity (>25%) and permeability (>1200md) in the Lower Tuscaloosa at stratigraphic depths below 20,000 ft. are influenced by chlorite coating the detrital grains. Chlorite coatings block quartz nucleation sites inhibiting quartz cementation. Chlorite coats in the Lower Tuscaloosa are controlled by the presence and abundance of volcanic rock fragments supplying the ions needed for the formation of chlorite. Chlorite decrease to the east in sediments derived from the Appalachian Mountains. An increase in chlorite in westward samples correlates with an increase of volcanic rock fragments derived from the Ouachita Mountains.
Rule-based and machine learning hybrid reservoir modeling for improved forecasting
(2021-08-13) Jo, Honggeun; Pyrcz, Michael; Lake, Larry W.; Prodanović , Maša; Olson, Hilary C.; Sun, Tao
Reservoir characterization becomes challenging in deepwater depositional systems where high exploration costs and complicated geological structures often limit data collection. Rule-based geostatistical subsurface modeling can overcome this data-gap challenge and produce geological representations for these reservoirs using geological rules constrained by even sparse data sets. The rule-based model simulates sediment dynamics through depositional rules in generating reservoir architecture and the associated rock properties distributions. As a result, rule-based models integrate conceptual information, including temporal deposition sequence and consequent compensational stacking patterns. However, selecting realistic rule parameters (e.g., stacking patterns and geometry of depositional elements) and integrating quantitative data (e.g., well logs and fluid production history) remain as obstacles to the broad application of rule-based subsurface models. In this research, I develop a robust rule-based modeling method for deepwater reservoir and machine learning-assisted data conditioning methods for various data (i.e., well data, stratigraphy, and production history) in the rule-based models. In this regard, I study the following subjects: (1) investigation of the realistic rule-parameters and removal of the numerical artifacts by comparing the models with geological observation, (2) solution to the long-standing conditioning challenge of rule-based models through the novel application of machine learning approach, and (3) examination of machine learning applications for a superior model inference model in standard geostatistical methods. The developed workflow enables reservoir characterization in deepwater reservoirs by reproducing their realistic geological heterogeneity and integrating various observed data into the models, resulting in accurate production forecasts. Moreover, the flexibility of the workflow can broaden its applications to different depositional settings, such as fluvial or deltaic reservoirs.
Stratigraphic architecture, depositional systems, and lithofacies of the Mississippian upper Barnett Two-Finger Sand, Midland Basin, Texas
(2018-01-25) Mauck, Justin Vaughn; Loucks, R. G.
The upper Barnett Two Finger Sand in West Texas forms oil and gas reservoirs that produce from natural fractures and low-permeability intraparticle matrix nano- to micropores. The section contains two mixed silt- to very fine sand-sized siliciclastic‒carbonate units that are composed of relatively thin 0.5 mm to 1 m hybrid/cogenetic event beds that amalgamate to form a deepwater submarine fan system in the Mississippian Tobosa Basin. Siliceous mudstones occur between these coarser grained units. The sediment sources for the fan lobes were from the northern and eastern margins (inner ramp) of the basin. The depositional setting, based on elevated TOC (up to 3.1%), lack of wave-related hydrodynamic features, and deepwater biota (cephalopods, Archeodiscus sp. foraminifera), is interpreted as having been below storm-wave base in a generally dysaerobic bottom-water setting with brief periods of oxygenation. Most of the TOC is Type III, but minor amount of Type II is present. Calculated Ro values average 1.2%, situating it in the late oil to early gas window. Core-plug porosity ranges between 0.5 to 4.4% and all permeability analyses were less than 0.001 md. Pore types include intraparticle fluid-inclusion pores and clay-platelet mineral pores. Some microvugs (<1 µm to 10 µm), that may be related to dissolution are observed. Rare organic-matter pores are present. Based on decline curves from producing wells and shut-in-pressure tests performed during the development of the Moonlight Field, it was concluded that the permeability network in the wells are natural fractures. After a few years of production, however, the decline curves suggest that some production is from the matrix. The concepts developed concerning the depositional setting and sediment-source areas and directions may aid in extending the development of the Two Finger Sand.
Structural framework and seismic geomorphology of the Cretaceous beneath the Mad Dog Area, deep to ultradeep waters Gulf of Mexico
(2013-05) Markez, Damian; Wood, Lesli J.
Recent drilling of deep stratigraphy in subsalt offshore Gulf of Mexico has revealed the presence of thick, amalgamated, Cretaceous siliciclastic reservoirs with the potential to become valid exploration targets. Similar to the Lower Tertiary deepwater play, the significant down-dip distance (> 400 km) from the source deltaics, the data gap across the modern structurally complex salt-tectonics-dominated slope and the difficulties of imaging subsalt stratigraphy pose challenges for the construction of meaningful deepwater system models to aid in exploration and appraisal efforts. A 3D seismic dataset in the Mad Dog field at the basinward end of the modern allochthonous salt canopy and outboard of the Sigsbee Escarpment offers the opportunity to study the nature of the deep stratigraphy at central positions in the basin. The nature of the Cretaceous sedimentary system has been investigated through detailed structural and seismic geomorphologic mapping. An early syndepositional contractional event has been identified and temporally associated with Mesozoic emplacement of a deep salt sheet. These events are masked by the major Neogene-age phase of fold amplification that dominates the present-day subsalt structural framework. Ponded-basin deepwater sedimentation processes control early phases of deposition in the Cretaceous Mad Dog area and sediment-gravity flows are deposited as complexes of low sinuosity amalgamated channelized deposits in roughly-confined sediment pathways. Ponded fills show internal lateral accretion architectures that grow sigmoid in nature as the migrating systems interact with the approaching minibasin margins making evident the structural control on sediment architecture. Later phases of deposition are characterized by slightly sinuous feeder channels with multiple lobe development at their terminus. Variable directions of sediment source pathways indicate a linear-sourced slope apron depositional model for these systems. In addition to the more structured morphologic elements, there were also pervasive mass-transport processes active, presumably triggered by Mesozoic halokinesis. Data in sparse deep wells in the GoM that penetrate the Cretaceous suggest that the Late Cretaceous deepwater depositional system was composed of coarse-grained high density gravity flows. The geometries seen in seismic beneath the Mad Dog area support the existence of such a basinwardly extensive deepwater fan systems developed during the Cretaceous, and the low sinuosity channel geometries and small length:width ratio and amalgamated nature of fan lobes suggest that these systems may have indeed been high-density in nature.