Investigation of the origin of shallow gas in outer Moray Firth open blocks 15/20c and 15/25d

This report briefly describes the evidence for the origin of shallow gas in Outer Moray Firth open blocks 15/20c and 15/25d. Sea floor pockmarks are known to occur within these blocks, and they indicate the seepage of gas from shallow levels into the local water column. An environmental concern is that any industry activity in these blocks must not plumb into any component of the system that is sustaining the gas seepages at sea bed. The conclusions of this study are: 1. Interpretation of the available BGS shallow seismic data and commercial site investigation data shows that gas is seeping from sea bed in three large active pockmark complexes in approximately 150 m or more water depth: the Challenger Pockmark Complex in the north of block 15/25d, the Scanner Pockmark Complex in the south of block 15/25d and the Scotia Pockmark which is adjacent to the north-east of the Scanner Pockmark Complex. 2. A review of the peer-reviewed scientific publications indicates that the majority of the arguments based on isotope analyses of gas and authigenic carbonate are for a predominantly biological origin for the gas seeping from the active pockmarks. However, biogenic isotopic signatures in the Gulf of Mexico and the North Sea are thought to have been generated when thermogenic hydrocarbons in shallow sediments were re-cycled by bacteria to produce ‘secondary’ methane with an identical isotopic signature to biogenic methane. Thus, the isotopic data derived from the Scanner Pockmark Complex do not provide a secure basis for determining whether the gas escaping from the pockmarks in block 15/25 is primarily biogenic or thermogenic in origin. 3. Interpretations completed during this project indicate that gas seeping to sea bed in the largest pockmarks is reservoired within the uppermost part of the Aberdeen Ground Formation, where it is preserved between buried sub-glacial channels. The gas seepages at sea bed are fed from an almost continuous blanket of buried gas-charged sediments situated between the sub-glacial channel margins at approximately 280-300 ms two-way time (around 120 m below sea bed) in the northern part of block 15/25d. 4. An empirical conclusion from distribution patterns observed in the interval between sea bed and 400 ms two-way time is that loss of shallow gas from the gas-charged interval at approximately 280-300ms two-way time will cut off the supply of shallow gas to the active pockmarks. Dry well 15/25b-1A, located immediately to the north of the Scanner Pockmark Complex, appears to have been drilled on the margin of the shallow gas reservoir. A recommendation is that future development operations should not disturb the shallow gas reservoir. 5. All of the hydrocarbon discoveries made within and around the study area are oil. The nearest Upper Jurassic Kimmeridge Clay Formation principal thermogenic gas kitchen lies some 30 km to the south-east, in the Fisher Bank Basin. Gas has been proved to have migrated up into Mid-Eocene sandstones (e.g. Alba Field) in that basin. Although it is possible that further vertical migration might have been achieved through minor faults and fractures in the Late Eocene to Pliocene, no evidence was observed in the 3D data to connect the location of the active pockmarks with supply from the thermogenic gas kitchen. For example, no gas chimneys have been observed within the Tertiary section on 3D seismic data across the study area.. Although no major faults have been found in 3D seismic data that transect the entire Eocene to Pliocene interval, minor polygonal faulting has been observed within the upper part of the Hordaland Group

The importance of stratigraphic plays in the undiscovered resources of the UKCS

This paper analyses the demographics of existing Un ited Kingdom Continental Shelf (UKCS) fields and discoveries as a means of assessing which plays are likely to offer the greatest untapped potential for stratigraphic traps. The talk is illustrated with examples of proven and untested stratigraphic traps

The remaining hydrocarbon potential of the UK Continental Shelf

The United Kingdom Continental Shelf (UKCS) has been a very successful exploration province in the last 38 years, with an average technical success rate of 31% from its 2150 exploration wells. Although the peak of exploration activity on the UKCS occurred during the 1980s and 1990s, there have been 41 technical successes from 82 wells in the last four years, representing an improved recent success rate of 50%. Estimates of undiscovered (yet-to-find) hydrocarbon volumes have been made from a database of prospects compiled over 20 years by the UK Government. This ‘bottom-up’ method provided an estimate of the yet-to-find resources at the end of 2002 of between 3.6 and 22.9 × 109 BOE recoverable. Methodology utilizing an inverse timescale to plot cumulative discovered volumes per year provides minimum estimates of between 4.5 and 9.5 × 109 BOE in place (c. 2.5 to 4.4 × 109 BOE recoverable). Pool size distribution methodology predicts that 11.5 × 109 BOE of in-place (c. 5.8 × 109 BOE recoverable) resources remain to be found on the entire UKCS. Geographically, the UK Central North Sea and Moray Firth area is predicted to contain the largest proportion of undiscovered resources (42%). Thirty-three per cent of the yet-to-find resources are judged to lie within the Atlantic Margin region. Eighty-three per cent of existing UKCS fields and discoveries are located within structural traps. The majority of stratigraphic and combination traps occur in association with syn-rift (Upper Jurassic) and post-rift plays. Many of the major discoveries in these traps were found serendipitously, and there has been relatively little direct exploration for stratigraphic plays. In the UK North Sea, there are few substantial remaining structural traps, except at considerable depth with attendant reservoir quality, high-pressure and high-temperature risks. The future of exploration is believed to lie with the search for subtle stratigraphic traps. Deep-water sandstone stratigraphic plays within the syn- and post-rift sequences offer the greatest potential for substantial new resources

Evidence of Color Coherence Effects in W+jets Events from ppbar Collisions at sqrt(s) = 1.8 TeV

We report the results of a study of color coherence effects in ppbar collisions based on data collected by the D0 detector during the 1994-1995 run of the Fermilab Tevatron Collider, at a center of mass energy sqrt(s) = 1.8 TeV. Initial-to-final state color interference effects are studied by examining particle distribution patterns in events with a W boson and at least one jet. The data are compared to Monte Carlo simulations with different color coherence implementations and to an analytic modified-leading-logarithm perturbative calculation based on the local parton-hadron duality hypothesis.Comment: 13 pages, 6 figures. Submitted to Physics Letters

Measurement of the B0-anti-B0-Oscillation Frequency with Inclusive Dilepton Events

The $B^0$-$\bar B^0$ oscillation frequency has been measured with a sample of 23 million \B\bar B pairs collected with the BABAR detector at the PEP-II asymmetric B Factory at SLAC. In this sample, we select events in which both B mesons decay semileptonically and use the charge of the leptons to identify the flavor of each B meson. A simultaneous fit to the decay time difference distributions for opposite- and same-sign dilepton events gives $\Delta m_d = 0.493 \pm 0.012{(stat)}\pm 0.009{(syst)}$ ps$^{-1}$.Comment: 7 pages, 1 figure, submitted to Physical Review Letter

Were New Labour’s cultural policies neo-liberal?

This article assesses the cultural policies of ‘New Labour’, the UK Labour government of 1997–2010. It takes neo-liberalism as its starting point, asking to what extent Labour’s cultural policies can be validly and usefully characterised as neo-liberal. It explores this issue across three dimensions: corporate sponsorship and cuts in public subsidy; the running of public sector cultural institutions as though they were private businesses; and a shift in prevailing rationales for cultural policy, away from cultural justifications, and towards economic and social goals. Neo-liberalism is shown to be a significant but rather crude tool for evaluating and explaining New Labour’s cultural policies. At worse, it falsely implies that New Labour did not differ from Conservative approaches to cultural policy, downplays the effect of sociocultural factors on policy-making, and fails to differentiate varying periods and directions of policy. It does, however, usefully draw attention to the public policy environment in which Labour operated, in particular the damaging effects of focusing, to an excessive degree, on economic conceptions of the good in a way that does not recognise the limitations of markets as a way of organising production, circulation and consumption

Helicity of the W Boson in Lepton+Jets ttbar Events

We examine properties of ttbar candidates events in lepton+jets final states to establish the helicities of the W bosons in t->W+b decays. Our analysis is based on a direct calculation of a probability that each event corresponds to a ttbar final state, as a function of the helicity of the W boson. We use the 125 events/pb sample of data collected by the DO experiment during Run I of the Fermilab Tevatron collider at sqrt{s}=1.8 TeV, and obtain a longitudinal helicity fraction of F_0=0.56+/-0.31, which is consistent with the prediction of F_0=0.70 from the standard model

Search for electroweak production of single top quarks in ppˉp\bar{p} collisions.

We present a search for electroweak production of single top quarks in the electron+jets and muon+jets decay channels. The measurements use ~90 pb^-1 of data from Run 1 of the Fermilab Tevatron collider, collected at 1.8 TeV with the DZero detector between 1992 and 1995. We use events that include a tagging muon, implying the presence of a b jet, to set an upper limit at the 95% confidence level on the cross section for the s-channel process ppbar->tb+X of 39 pb. The upper limit for the t-channel process ppbar->tqb+X is 58 pb. (arXiv