First Break - Volume 30, Issue 3, 2012

In a paper published to coincide with BP’s ‘Energy Outlook 2030’ Christof Rühl, Paul Appleby, Julian Fennema, Alexander Naumov and Mark Schaffer review evidence of the last two centuries of industrialization to analyze the evolution of energy intensity over the long- and short-run. Their analysis suggests among other things that high growth in per capita income over the next 20 years need not be constrained by resource availability. The text of this article can be found here.

Christoph Georg Eichkitz, Johannes Amtmann and Marcellus Gregor Schreilechner investigate the application and limitations of seismic attributes starting with the building of a unique database.

Krishnakumar Narayanan Nair, Odd Kolbjørnsen and Arne Skorstad, review seismic inversion and propose a fast and efficient way of estimating elastic properties and facies probability parameters using the results from inversion and through the incorporation of facies logs.

O. Ogunsanwo, B. Lee, H. Wahyu, E. Leung, V. Gottumukkala and F. Ruan describe a new 4D inflow control device optimization workflow developed using a sector model on the west flank of Field A, offshore Saudi Arabia.

Jonathan Henderson introduces a new approach to understanding and defining the 3D morphology of the geological elements imaged within the seismic data.

Farrukh Qayyum, Paul de Groot and Nanne Hemstra show that their HorizonCube-based transformation of seismic data provides a picture equivalent to the Wheeler diagram. Case studies from The Netherlands and Canada make the case.

Unresolved velocity anomalies in the near surface degrade deeper imaging. As a consequence, great care needs to be taken to ensure that all significant near-surface effects have been dealt with before attempting to build the deeper parts of a velocity–depth model. In order to incorporate velocity anomalies into the model, a range of options can be used, depending on whether the geobody geometry alone is discernible, or whether its velocity distribution is also known. Here I describe current industrial practice for building complex near-surface models, which is based on a range of approximate techniques, as well as the more complete solution offered by the emerging technology of waveform inversion. Although building complex nearsurface models is a painstaking process, a suitable near-surface velocity model can usually be obtained.

Principal stresses, that is vertical, maximum horizontal and minimum horizontal stresses, and elastic moduli related to rock brittleness, like Young’s modulus and Poisson’s ratio, can be estimated from wide-angle, wide-azimuth seismic data. This is established using a small 3D seismic survey over the Colorado shale gas play of Alberta, Canada. It is shown that this information can be used to optimize the placement and direction of horizontal wells and hydraulic fracture stimulations.

Probabilistic assessment of exploration prospects comprises two processes: estimation of risk, and estimation of uncertainty. Risk, R, is the chance of failure, while 1-R is the chance of success. Uncertainty is the range of volumes, and their associated exceedance probabilities, that we may encounter if we are successful. The chance of success is often impacted by the trap type. Fault-dependent closures are usually perceived as having lower chances of success than fault-independent closures. Combination traps, i.e., traps that are both fault-independent and fault-dependent, require a blurring of the distinction between uncertainty and risk. The chance of success for each trap type is used to define the uncertainty within the success case. In order to create the success case distribution of potential contacts in a combination trap, one must consider the chance of success for each individual trap type. Geologists who do not consider risk when assessing uncertainty may create success case distributions that cannot be technically supported.