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This work investigates the potential of QEMSCAN in assessing the pore structure system. 23 carbonate and clastic samples are analysed using QEMSCAN, which shows a good assessment of the macropore system (pore larger than 10µm). It defines the macropore system volume and delivers pore length distribution. The pore length distributions are integrated with plug-NMR results; a good match is observed between the two type of results, which enables a calibration of the T2 relaxation time with pore sizes. Compared to NMR data, QEMSCAN provide real pore measurements, which could be more accurate to use in permeability calculations.

Using a dense North Sea 4D dataset over the Golden Eagle field, we demonstrate the impact of OBN density on both the 3D and 4D seismic image by migrating progressively sparser node configurations. It is shown that 4D image quality is more sensitive to changes in node density than is the 3D image, and an acceptable sparse survey for 3D imaging may be inadequate for 4D. Mitigating the effects of reduced node density via processing shows partial success, but the tests highlights the importance of node density in 4D survey design for North Sea OBN data.

Challenged by the presence of strong anisotropy and velocity reversal in the near-surface, we apply structurally constrained anisotropic Multi-Wave Inversion (MWI), over 1200 km2 of OBC data offshore Abu Dhabi. MWI aims at simultaneously inverting the P-wave first breaks (FB), the ground roll Dispersion Curves (DC) and the Vertical Two-Way Times (VTWT) of main interfaces. In this study, MWI is extended to invert for epsilon that is constrained by the FB and the VTWT. We highlight the importance of proper preconditioning of the DC and FB inputs using data mining tools when applying the method to a large production dataset.

This paper shows how to calculate the bias due to misspecified models in least-squares parameter estimation. It introduces Omitted Variable Bias (OVB), a technique well known in least-squares analysis in the context of econometric data analysis. OVB is applied to the analysis of linearized isotropic AVO models, both analytically and numerically. For misspecified models, such as two-term AVO fitting with large angle range or with large contrasts, OVB provides relations between the biased and unbiased least-squares model parameters. A Jupyter notebook and binder link let’s the reader apply the ideas presented to their own AVO models.

An article summarizing CGG's recent Multi-Client seismic acquisition in the West of Shetland. Article covers the exploration history, key petroleum systems, geological challenges for seismic imaging and interpretation and identification of exploration opportunities within the data.

DALLAS–The great land grab in the Midland Basin has resulted in an exponential increase in acreage prices, with buyers paying up to $60,000 an acre in some cases. In this competitive environment, oil and gas companies–particularly smaller independents–are starting to look for prospective areas away from the main basin activity where land leasing costs can be significantly lower, drilling targets can be shallower, and reservoirs (sourced from migration) have the potential to yield economic volumes of hydrocarbon reserves. To identify and evaluate these types of plays, and to reduce exploration and development risks, it is essential to combine and interpret data within one space to provide a succinct geological evaluation of the subsurface, and ultimately, the potential resource in place. TriGeo Energy sought to conduct an integrated geological evaluation of its Wolfcamp assets in Sterling County, Tx., to identify potential drilling targets in the Eastern Shelf bordering the Midland Basin. TriGeo Energy’s leasehold is outside the current industry-defined economic boundaries of the Wolfcamp play to the west and south. The objective was to better understand if a viable and economic Wolfcamp play could be extended onto the Eastern Shelf environment. Figure 1 highlights defined Midland Basin petroleum plays and TriGeo’s acreage position. It also shows the locations of two 3-D seismic survey volumes over the company’s Sterling County acreage. With the study area on the Eastern Shelf and outside the Wolfcamp play’s defined extent (dashed blue line), it was essential to investigate and define the presence of the main petroleum system play elements–namely source rock quality and potential, reservoir thickness and quality, and ultimately, the presence of contained hydrocarbons.

Information for upcoming Geotraining Carbonate Petrophysics Course in December, 2021.

Information for Geotraining Fractured Reservoirs Course in November, 2021.

Information for Geotraining Carbonate Reservoir Geology course in November, 2021.