Anadarko’s Jupiter-1 exploration well in Block SL-07B-11 offshore Sierra Leone has encountered hydrocarbons. This has been confirmed by the results of drilling, wireline logs and samples of reservoir fluids.
The well, located over 25 kilometres west of the Mercury-1 well which discovered oil in the block, intersected 30 metres of hydrocarbon pay in the primary Upper Cretaceousobjective and did not encounter a hydrocarbon water contact. The well has been preserved for possible future re-entry, as the area is likely to require additional evaluation.
Jupiter-1 was drilled by the Transocean Discoverer Spirit drillship to a total depth of 6,465 metres in a water depth of 2,199 metres. On completion of operations, the drillship will move 15km northeast to the Mercury-2 well which will target several reservoir levels including extensions of the oil accumulations discovered by the Mercury-1 well.
Anadarko (55%) is Operator of offshore Block SL-07B-11 along with partners Repsol (25%) and Tullow (20%).
Angus McCoss, Exploration Director of Tullow, commented today:
“Jupiter is the third discovery in the Liberian Basin by Tullow and its Partners and provides further support for the stratigraphic play in the region. The presence of a working petroleum system producing gas and light oil in the basin is encouraging. Our technical teams will continue evaluating prospectivity across our significant regional acreage position. We will further test the play through the drilling of Mercury-2 in Sierra Leone and Kosrou-1 which is currently drilling in Côte d’Ivoire.”
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The research was sponsored by a grant from the center, which is a legislative agency of the Pennsylvania General Assembly.
The Center for Rural Pennsylvania is a bipartisan, bicameral legislative agency that serves as a resource for rural policy within the Pennsylvania General Assembly, its website indicates.
According to the report, this research studied the water quality in private water wells in rural Pennsylvania before and after the drilling of nearby Marcellus Shale gas wells. It also documented “both the enforcement of existing regulations and the use of voluntary measures by homeowners to protect water supplies.”
In its introduction, the authors said they evaluated water sampled from 233 water wells near Marcellus gas wells in rural regions of Pennsylvania in 2010 and 2011.
“Among these were treatment sites (water wells sampled before and after gas well drilling nearby) and control sites (water wells sampled though no well drilling occurred nearby),” the study indicated. “Phase 1 of the research focused on 48 private water wells located within about 2,500 feet of a nearby Marcellus well pad, and Phase 2 focused on an additional 185 private water wells located within about 5,000 feet of a Marcellus well pad.”
During that phase, the researchers collected both pre- and post-drilling water well samples and analyzed them for water quality at various analytical labs. During Phase 2, the researchers or homeowners collected only post-drilling water well samples, which were then analyzed.
The post-drilling analyses were compared with existing records of pre-drilling water quality, which had been previously analyzed at state-accredited labs, from these wells.
“According to the study results, approximately 40 percent of the water wells failed at least one Safe Drinking Water Act water quality standard, most frequently for coliform bacteria, turbidity and manganese, before gas well drilling occurred,” the report indicated. “This existing pollution rate and the general characteristics of the water wells, such as depth and construction, in this study were similar to past studies of private water wells in Pennsylvania.”
The study’s pre-drilling results for dissolved methane showed its occurrence in about 20 percent of water wells—although levels were generally far below any advisory levels.
“Despite an abundance of water testing, many private water well owners had difficulty identifying pre-existing water quality problems in their water supply,” the report indicted. “The lack of awareness of pre-drilling water quality problems suggests that water well owners would benefit from unbiased and consistent educational programs that explain and answer questions related to complex water test reports.”
In this study, statistical analyses of post-drilling versus pre-drilling water “did not suggest major influences from gas well drilling or hydrofracturing (fracking) on nearby water wells, when considering changes in potential pollutants that are most prominent in drilling waste fluids.”
When comparing dissolved methane concentrations in the 48 water wells that were sampled both before and after drilling, the research found no statistically significant increases in methane levels after drilling—and no significant correlation to distance from drilling.
“However, the researchers suggest that more intensive research on the occurrence and sources of methane in water wells is needed,” the report indicated.
The report then cited the Pennsylvania Oil and Gas Act of 1984, which indicates that gas well operators are “presumed responsible” for pollution of water supplies within 1,000 feet of their gas well for six months after drilling is completed if no pre-drilling water samples were collected from the private water supply.
“This has resulted in extensive industry-sponsored pre-drilling testing of most water supplies within 1,000 feet of Marcellus drilling operations,” the report states. “However, the research found a rapid drop-off in testing beyond this distance, which is driven by both the lack of presumed responsibility of the industry and also the cost of testing for homeowners.”
The authors of the study said their research suggests that a standardized list of minimum required testing parameters should be required across all pre-drilling surveys to eliminate confusion among between water supply owners and water professionals.
The study indicates that this standardized list should include bromide. The research found that bromide levels in some water wells increased after drilling and/or fracking. These increases may suggest more subtle impacts to groundwater and the need for more research.
“Bromide increases appeared to be mostly related to the drilling process,” the study indicated.
Additionally, “a small number of water wells also appeared to be affected by disturbances due to drilling as evidenced by sediment and/or metals increases that were noticeable to the water supply owner and confirmed by water testing results.”
Increased bromide and sediment concentrations in water wells were observed within 3,000 feet of Marcellus gas well sites in this study, suggesting “that a 3,000 foot distance between the location of gas wells and nearby private water wells is a more reasonable distance for both presumed responsibility and certified mail notification related to Marcellus gas well drilling than the 1,000 feet that is currently required.”
On the regulatory side, “the research found that regulations requiring certified mail notification of water supply owners, chain-of-custody water sampling protocols, and the Pennsylvania Department of Environmental Protection’s investigation of water supply complaints were generally followed, with a few exceptions.”
The study also concluded that “since voluntary stipulations were not frequently implemented by private water well owners” that more educational and financial resources should be made available to facilitate testing.
The authors were clear: “This research was limited to the study of relatively short-term changes that might occur in water wells near Marcellus gas well sites. Additional monitoring at these sites or other longer-term studies will be needed to provide a more thorough examination of potential water quality problems related to Marcellus gas well drilling.”
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- ‘Citizens Shale Commission’ weighs in on Marcellus policy (pennlive.com)