Rafik Baouche

Title : Characterizing in situ stress regime of the Oued Mya Basin, Northeastern Algerian Sahara: A statistical approach

Abstract:

The Paleozoic reservoirs of the Oyed Mya Basin in Algerian Sahara owing a great potential for hydrocarbonprospectivity, arenot well-understood in terms of its distribution of pore pressure and stress regime.This studyreports a comprehensive stress field interpretation for the first time froma proper geomechanical analyses of recently drilled eleven wells in the studied field. A cumulative length of 7000+m acoustic image logs were investigated and a mean NW-SE (128°-145° N) maximum horizontal stress (S_HMax) orientation is inferred from the B-D quality wellbore breakouts.The study integrates a log-based approach with the downhole measurements to infer pore pressure and insitu stress magnitudes. The vertical stress (S_v), estimatedusing the bulk-density profiles has an average gradient of 22.38 MPa/km. The Ordovician and Cambrian reservoirs have a pore pressure gradient of 13.47-13.77 MPa/km, which is more than the hydrostatic pressure regime.Following the univariate regression analyses to identify various influencing parameters on the S_HMaxmagnitude, we proposed multiple linear regression models to predict the minimum horizontal stress (S_hmin) and maximum horizontal stress (S_HMax)magnitudes based on pore pressure, S_v, Poisson’s ratioand Young’s modulus,respectively. The predicted S_hminandS_HMaxvalues are found to be in good agreement (goodness of fit as R²=0.976 and 0.995) with the measured data available from the fracture closure pressures during hydrofrackingand breakout widths from acoustic image logs. TheS_hmin and S_HMax gradients within the reservoirs range 17.2-18.3 and 23.8-26.5 MPa/km, respectively. Subsurface stress distribution in the central Saharan Algeria indicates that the present-day stress field in the Oued Mya Basin is principally strike-slip faulting(S_HMax> S_v> S_hmin).Inferences are drawn on the regional stress pattern and future drilling activities and reservoir development.

Biography:

Dr. Baouche Rafik studied Earth Sciences at the Rennes University, French and graduated as MS in 1979. He then joined the research group of Prof. Nedjari Ahmed at the Institute of Earth Sciences and geology, Bab Ezzouar Academy of Sciences (USTHB). He received his PhD degree in 2014 at the UMBB institution. After one-year postdoctoral fellowship supervised by Prof Baddari at the Geology and Laboratory, France he obtained the position of an Associate Professor at the UMBB. He has published more than 70 research articles in SCI (E) journals.)