My name is Chaouki Khalfi, Assistant Professor at the University of Gabès, Tunisia. I am a structural geologist with extensive expertise in petroleum geosciences, geophysics, drilling, and hydrogeology.
My expertise lies in geomechanics, which has become a key approach for optimizing drilling operations, as well as for reservoir simulation and exploration in both conventional and unconventional resources. This approach plays a fundamental role in improving reservoir characterization and enhancing our understanding of subsurface behavior.
In addition, geomechanics is increasingly critical in emerging energy applications such as carbon capture and storage (CCS) and hydrogen storage, where it is used to assess the integrity and long-term stability of geological formations. It also contributes significantly to geothermal energy exploration and development, supporting safe and efficient resource utilization.
Currently, my research focuses on applied geomechanics in reservoir studies, including CCS, unconventional reservoirs, and hydraulic fracture simulation. My work emphasizes borehole image analysis, in-situ stress determination, tectonic regime characterization, and pore pressure evaluation and its origins. These aspects are essential for ensuring wellbore stability, protecting groundwater resources, and optimizing production.
I am actively seeking research collaborations and project opportunities to further develop these topics and explore innovative solutions in geoscience engineering, geology, and geophysics.
I would be pleased to discuss potential collaborations and research initiatives with you.
Regards,
Chaouki KHALFI
Structural Geology; Petroleum Geosciences; Geology; Geophysics; Environment; Drilling; Hydrogeology
Through several stations on the forelimb of the Es Satah anticline belonging to Gafsa basin part of the southern Tunisian Atlas, an analysis of the striations encountered on the pebbles surfaces in the conglomerates of the growth-strata shows a remarkable variation; vertically and laterally from one station to another. Taking into account of the simple shear deformation, field observations have revealed several indexes of the flexural flow. Both of the tectonic and micro-tectonic studies in the Gafsa basin have shown the trending shortening (σ1) ranging from 150° to 180° N. Therefore, the striation azimuths were determined according to three profiles, I, II and III. These profile stretch from the NE to the SW on the forelimb of Es Satah anticline which displays a variation ranging from 167° to 138° N, from 165° to 147° N and from 154° to 138° N, respectively. Since these variations are incoherent with the regional shortening (σ1) direction, it allows us to discard any evidence of a direct relationship between the regional trending shortening (σ1) and the striation azimuths of the pebbles surfaces of growth-strata and to speculate a possible direct correlation between those variations and the kinematic evolution of the Es Satah anticline. Accordingly, we have suggested a conceptual model which paved the way to follow step by step the anterior stages of the deformation and identify the different palaeo-periclinal limits of the Es Satah anticline.
Summary This study consists of an assessment of the ecological accident implicating the Continental Intercalaire-11 (CI-11) water well located in Jemna oasis, southern Tunisia. The CI-11 ecological accident manifested in 2014 with a local increase of the complex terminal (CT) shallow water table salinity and temperature. Then, this phenomenon started to spread over the region of Jemna, progressively implicating farther wells. The first investigation task consisted of logging the CI-11 well. The results revealed an impairment of the casing and cement of a huge part of the 9⅝ in. production casing. Historical production records show that the problems seem to have started in 1996 when a sudden production loss rate occurred. These deficiencies led to the CI mass-water flowing behind the casing from the CI to the CT aquifers. This ecological accident is technically called internal blowout, where water flows from the overpressurized CI groundwater to the shallower CT groundwater. Indeed, the upward CI hot-water flow dissolved salts from the encountered evaporite-rich formations of the Lower Senonian series, which complicated the ecological consequences of the accident. From the first signs of serious water degradation in 2014 through the end of 2018, several attempts have been made to regain control of annular upward water flow. However, the final CT groundwater parameters indicate that the problem is not properly fixed and communication between the two involved aquifers still persists. This accident is similar to the OKN-32 case that occurred in the Berkaoui oil field, southern Algeria, in 1986, and included the same CI and CT aquifers. Furthermore, many witnesses claim that other accidental communications are probably occurring in numerous deep-drilled wells in this region. Concludingly, Jemna CI-11, Berkaoui OKN-32, and probably many other similar accident cases could be developing regional ecological disasters by massive water resource losses. The actual situation is far from being under control and the water contamination risk remains very high. In both accidents, the cement bond failure and the choice of the casing point are the main causes of the internal blowout. Therefore, we recommend (1) a regional investigation and risk assessment plan that might offer better tools to predict and detect earlier wellbore isolation issues and (2) special attention to the cement bond settlement, evaluation, and preventative logging for existing wells to ensure effective sealing between the two vulnerable water table resources. Besides, in the CI-11 well accident, the recovery program was not efficient and there was no clear action plan. This increased the risk of action failure or time waste to regain control of the well. Consequently, we suggest preparing a clear and efficient action plan for such accidents to reduce the ecological consequences. This requires further technical detailed study of drilling operations and establishment of a suitable equipment/action plan to handle blowout and annular production accidents.
Oil exploration is usually carried out using conventional techniques such as seismic reflection and exploratory drilling. However, these techniques are very costly with a high risk of dry holes or failure to find commercial quantities of hydrocarbons. Here we aim to evaluate surface geochemical prospection (SPG) methods which serve as preliminary step to derisk an area by exploring hydrocarbon micro-seeps. This approach helps to identify potential areas of interest when you have limited amount of money to explore a given area. This paper reports on surface gas micro-seepages in the Kerkennah archipelago, part of the Tunisian Pelagian Platform. 33 gas and soil samples were collected on a 1 × 1 km grid over Chergui Island. Both free gas and adsorbed soil gas techniques were used. Free hydrocarbon gas concentrations ranged from 0 to 21 ppm. Adsorbed gases showed concentrations up to 11 ppm. The presence of all light hydrocarbon gas components from methane to pentane, the values of the gas ratios C1/C2, C1/ΣC2+, (C3/C1) x 1000 and C1/(C2 + C3), and the Pixler and triangular diagrams together indicate that these gases are of thermogenic origin and have migrated from subsurface accumulations. Anomalous concentrations of hydrocarbon gases occurred in the middle and west of the study area. Both free and adsorbed gas anomalies have the same planar shape and form linear anomalies with a NW-SE trend. This orientation corresponds to that of the major fault system affecting the Kerkennah archipelago. Subsequent independent VES surveys and re-interpreted seismic lines confirmed the presence of a surface fault as suggested by the surface gas anomalies. In conclusion, our study has confirmed the presence of thermogenic hydrocarbon gas microseepage to the surface. The gases are interpreted to have migrated to the surface along faults. SPG methods were thus able to identify active hydrocarbon migration and can be considered as a useful low-cost approach to hydrocarbon exploration.
In this work, we integrated structural investigation, wells and seismic interpretation with analysis of magnetic anisotropy with the objective to reconstruct the kinematic evolution of the NE-SW trending Semmama anticline, located in the the central Tunisian Atlas province. Based on lithostratigraphic correlation, we observed a thickening of the Aptian-Albian levels towards the North compatible with a scenario of syn-tectonic sedimentation, as controlled by ESE-WNW striking normal faulting. The anisotropy of magnetic susceptibility (AMS) results displayed both normal and reverse fabrics for the sampled outcropping formations. To interpret the reverse magnetic fabrics, we performed Anisotropy of Anhysteretic Remanent Magnetization measurements to define their normal configuration. Both magnetic methods showed well-defined magnetic fabrics with NESW to N-S trending magnetic lineation that is consistent with the Early Cretaceous extensional phase. We then built a balanced cross-section, where we interpreted the Semmama anticline as a fault-propagation fold during backthrusting. The main detachment level is situated in the Triassic succession at the depth of 5.5 km and the fold has an estimated shortening of 2.2 km. We proposed that the ESW-WNE normal faults were reactivated during the Tertiary NW-SE compressional event forming the present day back-thrusting structure.
The recent discovery of surface oil seeps in the Tamerza area in the west‐central Gafsa Basin (southern Tunisia) has prompted a re‐evaluation of the hydrocarbon potential of the region. In this paper, we report the results of analyses of seep oils by Rock‐Eval pyrolysis (n = 6) and gas chromatography – mass spectrometry (n = 4). The goals of the study were to assess the composition of the seep oils, to investigate the relationship between the seep oils and potential source rocks, and to highlight the significance of the seep oils for oil exploration in the region. In the Tamerza area, surface oil seeps have been recorded in numerous formations ranging between the Upper Cretaceous Abiod Limestone Formation and the lower Miocene Sehib Siltstone Formation. The results of this study showed that all the seep oil samples analysed in general had a similar geochemical fingerprint: for example, Pr/Ph values are lower than 1; a plot of Pr/n‐C 17 (0.27‐ 0.36) versus Ph/n‐C 18 (0.3‐0.8) indicates a marine source rock deposited under reducing anoxic conditions; and Ts/(Ts+Tm) ratios indicate that the source rock was thermally mature. Correlation studies suggest that the oils originated from Cenomanian‐Turonian shales corresponding to the informally‐named Bahloul equivalent formation. Oil expulsion from this source rock at the seep locations is inferred to have ended by middle Miocene time. However the main phase of folding occurred here in the Pliocene – early Quaternary, and the resulting anticlinal folds are not therefore prospective structural traps for hydrocarbons because they developed after migration had already ceased. Stratigraphic traps and salt structures in the region may be of greater exploration interest. A surface oil seep sample was also recovered from the Quaternary upper Segui Formation at Jebel Orbata in the east of the Gafsa Basin. Analysis of this oil sample showed that it has similar geochemical characteristics to the seep oils from the Tamerza area, but that it appears to have had a much more recent migration history. In the eastern Gafsa Basin, Pliocene – early Quaternary anticlinal structures could therefore constitute effective structural traps charged by the same Bahloul equivalent formation source rock.
Actively looking for research collaboration opportunities in Geology, Geomechanics, and Interdisciplinary Earth Science Fields.