Abstract. Erosion of rock cliffs has been considered to be relatively unpredictable. This perceived stochastic nature of the erosional processes often occurs through collapses along fractures in the rock-mass. The prediction of catastrophic cliff failures and collapses remains very difficult. For advancing in this field, it is important to understand the processes through which a crack is initiated, how it develops and propagates until the final failure. This paper examines the micro-seismic signals recorded 15 h prior to a rock-fall located at Mesnil-Val, France. The results lead to the hypothesis that several phases of failure mechanisms contribute to rock-fall occurrence. The most important phases were associated with micro-seismic event families identified by multiplet selection. Each event family contained one specific frequency spectrum showing a progressive decrease of the frequencies as the rock approached failure suggesting the following phases: 1) the micro-seismic events recorded 15 h before the rock-fall were characterised by the highest frequencies in a large spectrum-band, between ∼100 and 1000 Hz (family 1), suggesting a crack initiation mechanism or the opening of existing fractures; 2) the micro-seismic events recorded several minutes before the rock-fall were associated with a clear decrease in the highest frequency components (family 2) suggesting that the mechanism was related to the growing and development (or coalesce) of existing micro-cracks into larger fractures; 3) micro-seismic events recorded just before the rock-fall were associated with Correspondence to: G. Senfaute (gloria.senfaute@ineris.fr) a lower frequency spectrum than families 1 and 2, the highest frequency components were absent (family 3), the frequency emission source mechanism could be related to the shearing or opening of the existing large fractures permitting the complete detachment of the blocky rock-mass; 4) finally, micro-seismic events with a very low frequency spectrum (lower than 100 Hz) characterized the rock-fall impact on the ground. These encouraging results offer the possibility of using the micro-seismic system to monitor high risk sections of coastline and to advance understanding of cliff failure mechanisms.

Abstract. The prediction of permeability in tight carbonate reservoirs presents ever more of 8 a challenge in the hydrocarbon industry today. It is the aim of this paper to ascertain which 9 models have the capacity to predict permeability reliably in tight carbonates, and to develop a 10 new one, if required. This paper presents (i) the results of laboratory Klinkenberg-corrected 11 pulse decay measurements of carbonates with permeabilities in the range 65 nD to 0.7 mD, 12(ii) use of the data to assess the performance of 16 permeability prediction models, (iii) the 13 development of an improved prediction model for tight carbonate rocks, and (iv) its 14 validation using an independent data set. Initial measurements including porosity, of the models were developed especially for tight gas sands, while many were not. Critically, 21 none were developed for tight gas carbonates. Predictably then, the best prediction was carbonates, will lead to gross errors and that the development of new methods that are 33 specific to tight carbonates is unavoidable.

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Abstract. The distribution of reservoir quality in tight carbonates depends primarily upon how 9 diagenetic processes have modified the rock microstructure, leading to significant heterogeneity and 10 anisotropy. The size and connectivity of the pore network may be enhanced by dissolution or reduced by 11 cementation and compaction. In this paper we have examined the factors which affect the distribution of 12 porosity, permeability and reservoir quality in the Turonian-Campanian Kometan Formation, which is a 13 prospective low permeability carbonate reservoir rock in northern Iraq. Our data includes regional 14 stratigraphy, outcrop sections, well logs and core material from 8 wells as well as a large suite of 15 laboratory petrophysical measurements. These data have allowed us to classify the Kometan formation 16 into three lithological units, two microfacies and three petrofacies.