Shell Pipeline's Response And Repairs After Hurricane Ivan

A climatology of various ocean features in the Gulf of Mexico (GOM) was developed using the combination of satellite remote sensing and in situ data that spanned periods as long as 32 years. Twelve separate statistics were created, some of which described characteristics of the Loop Current, while others are involved with warm core rings that separate from the Loop Current and cold core rings. These statistics examined the frequency with which the Loop Current was found in the GOM, the orientation of the Loop Current, the frequency of intrusion of Loop Current water onto the west Florida shelf and into the GOM common water region, ring separation period from the Loop Current, ring dissipation, ring speed, ring path, frequency of ring water in the western GOM, and the frequency of warm and cold core rings (WCRs and CCRs, respectively) in the GOM. The results indicate that CCRs were principally responsible for mass and heat redistribution in the eastern GOM (EGOM) and WCRs are responsible for mass and heat redistribution in the western GOM (WGOM). The average period for WCR separation from the Loop Current was 11 months and the range from 5 to 19 months. WCRs moved through the WGOM most often using the central path (i.e., their trajectory was found between 24° and 26°N latitude) and they decreased to about 55% of their initial size when they reach the western wall of the GOM. CCRs were most often found in the EGOM, and their frequency of occurrence in the EGOM surpassed that of WCRs anywhere in the GOM.

Cyclonic activity in the eastern Gulf of Mexico: Characterization from along-track altimetry and in situ drifter trajectories

Near-inertial oscillations in the deep Gulf of Mexico

U-Pb detrital zircon geochronology, supplemented by thin section petrography, point counting, and well logs, were used to constrain the provenance of basal Triassic/Jurassic (?) clastic sedimentary rocks in the Eastern Gulf of Mexico (EGOM). Basal clastics were deposited as syn-rift strata into half grabens present along the EGOM and eastern margin of Laurentia that formed during the initial break up of Pangea. Samples used in this study were collected from the South Florida Basin (SFB) and the South Georgia Rift (SGR). Previous studies of post-rift Jurassic sediment in the Gulf of Mexico has identified a change in source from Laurentian dominated sources in southern Mississippi/Alabama, to Gondwanan dominated sources in the Florida Apalachicola Embayment/offshore. Comparing the provenance of initial syn-rift strata to post-rift strata is used to identify initial sediment sources into the EGOM rift basins, and how provenance changed over time. Detrital zircons were collected from five SFB well cutting samples from the Jurassic (?) Wood River Formation and proximal basal sandstones, and six SGR well cutting samples from the Triassic (?) Newark Supergroup, as well as one sample from offshore southern Florida basement. Predominant age populations for the SFB are consistent with a Pan-African origin (525-680 Ma, 1900-2200 Ma). Samples from the SGR are dominated by Laurentian sources (265-330 Ma, 350-420 Ma, 430-490 Ma, 900-1300 Ma), as well as secondary Pan-African sources (525-680 Ma, 1900-2200 Ma). Provenance data is supported by thin section point counting and well logs. Samples in the northern SGR are predominantly derived from Laurentian sources, while the southern samples 3137 and 1854 are a mix of Laurentian and Gondwana signatures. K-S test comparisons of basal sandstones from this study and post-rift Jurassic Norphlet Formation samples from Lovell (2010) and Lisi (2013) show little correlation between samples, implying they do not share similar sources. The exception is the offshore Apalachicola Embayment samples, which indicates that the SGR may have been a potential source for Jurassic sediment in the northern EGOM. The integration of geochronology and petrographic techniques in this study suggests a mix of primarily sedimentary sources from the Suwannee Terranes and metamorphic sources from Laurentia supplied the initial sediment into the EGOM. Results from this study can be used to better constrain tectonic terranes and paleogeography of the early EGOM.

The Black Drum Pogonias cromis is an abundant estuarine-dependent fish that supports recreational and commercial fisheries. We examined the phylogeography and historical demography of the Black Drum along the Atlantic and Gulf of Mexico coasts of the United States using mitochondrial DNA sequences and nuclear DNA microsatellites. Black Drum exhibited high haplotype diversity and low nucleotide diversity across its range. We observed 249 haplotypes that resolved into two haplogroups: haplogroup 1 was most abundant along the Texas coast, and haplogroup 2 was more abundant in the Atlantic Ocean and the eastern Gulf of Mexico. Analysis of molecular variance, pairwise estimates of genetic differentiation, assessment of isolation by distance, Bayesian clustering, and multivariate ordination indicated that most population structure within Black Drum was associated with a western Gulf of Mexico versus Atlantic–eastern Gulf of Mexico split. However, analysis of molecular variance, haplotype diversity, and measures of genetic differentiation provided evidence of weak population structure on the Texas coast, perhaps due to a of combination of isolation by distance and limited emigration into and dispersal from the upper and lower Laguna Madre on the lower coast. Mismatch distributions, neutrality tests, and Bayesian skyline plots suggest that haplogroup 1 underwent rapid demographic and range expansion approximately 15,000 years ago, whereas the demographic and range expansion of haplogroup 2 was more gradual and began earlier (circa 25,000–30,000 years ago). Our results suggest that Black Drum may benefit from being managed as two stocks: (1) western Gulf of Mexico and (2) Atlantic Ocean plus eastern Gulf of Mexico. Additionally, weak but significant genetic divergence in the Laguna Madre coincides with known life history divergence in this region. Caution should be used regarding the management of Black Drum in Texas as a single demographic unit.

Ram Powell is a stratigraphically trapped sequence of turbidite reservoirs in 2,500-4,000 ft of water in the Eastern Gulf of Mexico. The discovery was made in 1985 and the field has been the subject of extensive geoscience and engineering studies. In spite of this work there is still significant uncertainty in Ram Powell reserves. The Ram Powell development plan is underway, with fabrication of a tension-leg platform and 60,000 b/d plus 200 MMcf/d facility. Drilling will include 7 high rate horizontal wells and 3 water injection wells. Reserves accessed in this development scheme are approximately 250 million barrels equivalent. Model-based seismic inversion (constrained by 12 appraisal penetrations, rock property data and seismic interpretation) was employed over the main reservoir interval (J, L and N sands) to create models that are consistent with 3D seismic data. These models were used in several simulation studies including element models to determine optimal well placement, and full-field models to predict overall reservoir performance. The results of the study both reduced and enabled management of reservoir volume uncertainty; they were critical for determining the number, horizontal length and placement of wells (vertically and areally). The results also provided the basis for a proposal to increase the facility capacity limits to 70,000 b/d plus 260 MMcf/d. Some significant learnings are (1) model-based inversion is now in a production mode that can be rapidly applied to reservoir problems, (2) many reservoir complexities are simply below seismic resolution and inversion is unable to add with certainty significantly more resolution and, (3) detailed reservoir models that reflect reservoir conditions and are easily manipulated are required for reservoir optimization. Introduction Purpose. The Ram Powell Field is currently under development with fabrication of a tension-leg platform and 60,000 b/d and 200 MMcf/d production facility. Development will include 7 high rate horizontal wells and 3 water injection wells with a single subsea well drilled much later. Production is scheduled to begin in August, 1997 and the expected reserves are 250 million barrels equivalent. The purposes of this paper are (1) to describe the process used to integrate 3D seismic, geological, and rock property data into a static model that was used for reservoir simulation, (2) to illustrate how the modeling was used to manage uncertainty, and (3) to illustrate the impact of this work on development planning and facility design. Setting. Ram Powell is a stratigraphically trapped sequence of turbidite oil and gas reservoirs in 2,500-4,000 feet of water in the eastern Gulf of Mexico. The discovery was made in 1985 and has had extensive geoscience studies performed since then by each of the Ram Powell joint venture partners. A fairly extensive set of data is available including three 3D seismic surveys, twelve wells (drilled from five surface locations), 420 feet of conventional core, one production test, in addition to the normal set of petrophysical logs, RFT's, and sidewall samples (Figures 1, 2 and 3). In spite of the extensive data set, uncertainty remains with respect to Ram Powell reserves. Uncertainty in reservoir limits, net thickness, effective permeability (vertical and horizontal), fluid properties, well placement, and well design all have an impact on reservoir performance prediction (rate and cumulatives). There are three reservoirs in the initial development phase (J, L, and N sands). P. 477

Although numerous studies on mesoscale eddies in the Gulf of Mexico (GoM) have been conducted, a comprehensive study on their temporal and spatial characteristics is still lacking. In this study, we combine three eddy detection algorithms to detect eddies from the 26-year sea surface height record in the GoM and examine their characteristics. We find distinct characteristics between Loop Current Eddies (LCEs), Loop Current Frontal Eddies (LCFEs), and mesoscale eddies that are not directly related to the Loop Current (LC). Seasonal variability appears in both the LCFEs and non-LCFE cyclonic eddies and shows large uncertainties. More specifically, more LCFEs are formed in January to July than in August to December, likely related to the seasonal variation of the northward penetration of the LC. And the formation of non-LCFE cyclonic eddies shows a biannual variability, which could be linked to the position and strength of the background current in the western GoM. Low-frequency (interannual to multidecadal) variability is also detected. In the eastern GoM, the extent of northward penetration of the LC can affect the generation of LCFEs and result in low-frequency variations. In the western GoM, the low-frequency variability of eddy occurrence and amplitude could be related to the surface circulation strength. This study can serve as an up-to-date reference for eddy-related investigations in the GoM.

Congratulations are due this year’s winners of the Offshore Technology Conference (OTC) awards. The recipients will be honored during OTC, which runs 2–5 May at the Reliant Center in Houston. The OTC Distinguished Individual Achievement Award will recognize J. Kim Vandiver, a professor at the Massachusetts Inst. of Technology. He is being honored for his technical breakthroughs in the dynamics of vortex-induced vibration, which have enhanced the design of structures to with-stand high ocean currents, enabling oil and gas production to occur in progressively deeper water. The 2005 OTC Distinguished Achievement Award for Organizations goes to Kerr-McGee Oil and Gas Corp. and Technip for their pioneering efforts in the Gulf of Mexico in delivering three generations of spar floating production systems in 9 years. This is the second OTC award for Kerr-McGee in recent years. In 2002, the company won the same award for its Neptune Spar project, the first spar production platform. Kerr-McGee and Technip have developed a total of five production spars, using three different designs, over the past decade. The collaboration resulted in the world’s first production spar—now referred to as a “classic” spar design—which was installed at the Kerr-McGee-operated Neptune field in the eastern Gulf of Mexico in 1997. In 2001, the companies developed the world’s first application of truss spars at the Kerr-McGee-operated Nansen and Boomvang gas fields in the East Breaks area of the Gulf of Mexico. Nansen lies in 3,678 ft of water, while Boomvang is in 3,453 ft. Another truss spar for the Gunnison field began production in 2002. Last year saw another world’s first with the development and delivery of the third-generation spar, called a “cell spar,” for the Kerr-McGee-operated Red Hawk field in the Gulf’s Garden Banks Block 877. Kerr-McGee holds a 50% interest in the field, with Devon Energy also taking a 50% share. Red Hawk is a two-well subsea development in 5,300 ft water depth. A sixth spar, using the truss design, is currently under construction for another deepwater project at Kerr-McGee’s Constitution field. The cell spar is designed essentially as an alternative to a long-distance tieback. The design consists of a vertical configuration of seven cylinders that are 20 ft in diameter and form a giant column that supports a 4,700-ton production platform. The spar is anchored to the seafloor by polyester moorings that are lighter, less expensive, and less corrosive than steel cables. Red Hawk’s production is at 120 million ft3/D of gas with expansion capacity of up to 300 million ft3/D. The breakthrough with the Red Hawk spar was its economy and small size. The less expensive cell spars will enable producers to look at deepwater reserves that in the past might have been too small to develop. Reserves previously required approximately 100 mil-lion BOE to justify development, but with smaller production platforms, reserves of less than half that size are now viable. Other producers have begun to adopt Kerr-McGee’s and Technip’s groundbreaking technology. Thirteen spars have been installed in the Gulf of Mexico, and Technip has built 10 of them and is currently constructing another. Technip also just signed a contract with Murphy Oil for the construction of a spar for the Kikeh field in Malaysia, which will be the first spar installed outside the Gulf of Mexico.

Pulley Ridge, a limestone ridge that extends nearly 300 km along the southwestern Florida shelf in the eastern Gulf of Mexico, supports a mesophotic coral ecosystem (59 to 94 m deep), surrounded by deeper waters. An ongoing evaluation of Porifera biodiversity observed and collected during expeditions by Harbor Branch Oceanographic Institute (2003-2015) have shown the existence of approximately 102 sponge species, with at least 20 species new to science. The present paper describes two novel Poecilosclerida from mesophotic reefs and deep escarpments in the Pulley Ridge Region, Eastern Gulf of Mexico, namely Discorhabdella ruetzleri n.sp. (Crambeidae, Poecilosclerida) and Hymedesmia (Hymedesmia) vaceleti n. sp. (Hymedesmiidae, Poecilosclerida). This is the first record of Discorhabdella for the greater Caribbean and the Central West Atlantic. The skeleton of D. ruetzleri n.sp. includes the unique pseudoastrose acanthostyles of the genus, and it is distinct from congeners in the size ranges of the megascleres and in the occurrence of predominantly smooth instead of tuberose choanosomal and ectosomal subtylostyles. The intense blue color and the spicule combination of Hymesdesmia (H.) vaceleti n.sp. makes this species unique among other Hymedesmia spp. from the western Atlantic. The discovery represents a considerable expansion in the known biogeographical distribution of the genus Discorhabdella which is represented now by six species with a discrete geographic distribution (New Zealand, Azores, Western Mediterranean Sea, Eastern Pacific in Panama). This work is the first contribution to an ongoing effort to discover and document the importance of sponge biodiversity on mesophotic reefs and associated deep-water habitats in the Gulf of Mexico and the Caribbean.

Objective Understanding the spatial connectivity of elasmobranch populations is critical for regional fisheries management. The Blacktip Shark Carcharhinus limbatus is abundant in coastal waters of the Gulf of Mexico (GoM) and important in recreational and commercial fisheries. Based on genetic and tagging studies, GoM Blacktip Sharks are currently managed under separate quotas between the eastern and western GoM (divided at 88°W), but no studies have used vertebral chemistry to assess the population structure of adult Blacktip Sharks. Methods We compared vertebral elemental signatures (barium [Ba], magnesium [Mg], manganese [Mn], strontium [Sr], and zinc [Zn]) for the first year of life with last occupied habitats (vertebral edges) in Blacktip Sharks collected from the western (Texas and Louisiana) and eastern (Alabama and Florida) coastal waters of the northern GoM. Result We found significant regional differences in Ba, Mg, Mn, and Sr vertebral edge signatures, suggesting ecological separation of Blacktip Sharks. Significant correlation between first-year and edge signatures suggested a high degree of residency between life stages. Cross-validated discriminant function analyses yielded highest regional classification accuracies when Florida sharks were grouped separately west of 88°W (90%), demonstrating the unique elemental signatures of eastern versus western GoM Blacktip Sharks under current management delineations. Conclusion Combined, these findings demonstrate that trace element markers can distinguish regional populations of Blacktip Sharks and provide a complimentary approach in addition to genetics and physical tagging to support current stock management efforts. Abstract Impact statement Stocks of Blacktip Sharks are managed under separate quotas in the eastern and western Gulf of Mexico. In this study, elemental signatures in mineralized vertebral cartilage of Blacktip Sharks confirm ecological population separation. Natural chemical tags in shark vertebrae offer an additional tool to characterize population connectivity and stock delineation for highly migratory shark species.

A historical assessment of Karenia brevis in the western Gulf of Mexico

Overlap between Atlantic bluefin tuna spawning grounds and observed Deepwater Horizon surface oil in the northern Gulf of Mexico

Fish‐mediated carbon export provides a significant proportion of the biological carbon pump in oligotrophic regions. Bioenergetic models estimate this carbon transport, but many lack species‐specific traits and no carbon export model has been developed in the mesopelagic Gulf of Mexico. Intensive mesopelagic sampling efforts in the northern and eastern Gulf of Mexico have provided high‐resolution information regarding community composition, species' vertical migratory characteristics, diel depth occupancies, and diets. A stochastic, individual‐based model was developed for deep‐pelagic fishes in the northern Gulf of Mexico to estimate bioenergetic rates and carbon export fluxes. Fishes that ate gelatinous zooplankton consumed more mass per body weight per day than predators of cephalopods and fishes, ostensibly to increase the throughput of prey with less carbon (gelata) or more refractory materials (Crustacea). A dynamic energy budget submodel indicated that during 81% of occurrences, asynchronous vertically migrating fishes rested for 1 d before migrating again, but migrations on successive days were possible. In terms of carbon export, myctophids and stomiids contributed greater than 53% and 12% of the active carbon flux for the entire assemblage in all scenarios. The assemblage‐wide carbon export rate driven by vertically migrating fishes was 0.14–0.72 mg C m−2 d−1, 61% of the ingested carbon by the assemblage. Incorporating species‐specific traits and individual variability in bioenergetic models allows for more complex research questions (e.g., the effect of feeding guilds and asynchronous migration on carbon export) compared to the carbon export models that otherwise assume all fishes within a functional group are equivalent.

The trophic ecology of the stomiid assemblage (Pisces, Stomiiformes, Stomiidae) in the eastern Gulf of Mexico, a region with physical and biological characteristics typical of oligotrophic low-latitude regimes, was investigated. Over 1400 specimens representing 69 species and 17 genera were examined. Four patterns of feeding were evident among the abundant stomiids: (1) myctophid predation; (2) zooplankton/small micronekton predation; (3) penaeidean shrimp predation; and (4) copepod/micronekton predation. One rare species preyed on cephalopods. Il was concluded that stomiids exhibited a high level of prey-selectivity, particularly considering the broad range of prey types available in the eastern Gulf of Mexico. The absence of numerically dominant potential prey (e.g.Cyclothone spp., sternoptychids) in the diets of piscivorous stomiids is possibly a function of feeding periodicity coupled with stomiid vertical migration. Stomiids may feed at night in the upper 200 m on vertically migrating myctophids while disregarding co-occurring nonmigrating prey during the daytime. Integration of stomiid abundance and diet data suggests that: (1) stomiids are the dominant upper trophic-level predators of the Gulf of Mexico mesopelagial, (2) stomiids inflict the highest predation impact on myctophids in low-latitude midwater ecosystems, and (3) the historic use of predation-avoidance arguments to explain certain mesopelagic phenomena (e.g. vertical migration, ventral photophores) appears to be substantiated by estimates of stomiid predation-impact. The stomiids may serve as key trophic mediators in the transfer of energy from the mesopelagial to the bathyand benthopelagial.

Monohull based production platforms are the most widelyused floating production systems worldwide. They are proven as a reliable workhorse and have provided the industry with a commercially attractive platform for producing large and small offshore oil developments in most major offshore producing regions. The ship-shaped monohull offers low cost "real estate" for production facilities, and its integrated storage and offloading feature eliminates the oil export pipeline. To date an FPSO * has not been employed in the US Gulf of Mexico because of the extensive infrastructure of existing host platforms and pipelines on the continental shelf. However, in recent OCS lease sales, operators have acquired vast, undeveloped acreage that is increasingly remote from this infrastructure. Beyond the shelf, the potential for a low capital cost platform and elimination of, what can be a cripplingly expensive oil export trunkline, has many operators considering FPSOs to develop these remote, deepwater prospects. This paper examines and discusses major technical and regulatory issues that the industry (regulators, operators, contractors) must collectively address prior to introducing the first FPSO into the US Gulf of Mexico. * Abbreviations are explained at the end of the paper. Introduction The monohull FPSO was first used to produce the small Castellon field in the Mediterranean Sea in 1977. The system produced 20,000 bopd from a single subsea well tied-back to a turret moored converted tanker in 350 feet of water. This FPSO was the genesis of what has become the most widely employed floating production system worldwide. Over 60% of the worlds floating production platforms in use today are either converted from tankers or are purpose built monohulls. From 1977 to 1993, 24 FPSOs were installed, 17 of which were conversions. They were mostly used to develop small oil fields in areas remote from pipeline infrastructure. Large integrated oil storage capacity permited periodic shuttling of parcels of produced crude in shuttle tankers to a sales point, while enabling uninterrupted production and eliminating the need for an oil pipeline. These FPSOs proved to be reliable workhorses, that gave operators a commercial option to exploit marginal, remote oil fields. As confidence in these systems grew, along with technological advances in subsea wells and flexible risers, operators began to expand their application to progressively larger developments in increasingly deeper waters and harsher environments. Since 1994, 36 FPSOs have been installed. Of these, 15 are in the demanding North Sea and Atlantic Frontier Provinces. Petrobras has converted several VLCCs for use as FPSOs in the Campos basin in water depths upto 6000 feet. Table 1 captures the progression of FPSOs from its humble beginnings at Castellon, to the most technologically advanced FPSO recently installed in Statoils Asgard field in the Norwegian North Sea. Despite its widespread and burgeoning use, only one FPSO has been employed to develop an offshore field in US waters. That was Exxon's Offshore Storage and Treating Unit (OS&T) that operated in the Santa Barbara Channel in 500 feet of water from 1981 to 1995. A monohull FPS has never been used in the US Gulf of Mexico, one of the most prolific offshore oil and gas producing regions in the world.