The presence of natural fracturing in the Thamama Reservoir was postulated following its discovery in 1958. The performance of this reservoir was poorly understood being based on information gathered from a small number of well tests executed during the 1960’s and 70’s. An up to date assessment of this reservoir was sought utilising the latest reservoir monitoring technology. The objective was to confirm the existence, magnitude and orientation of any fracturing in the Thamama reservoir. A further objective was to evaluate their distribution within the zones of the Thamama reservoir. The surveillance programme included multi-well interference testing, pressure build-up testing, production logging and water saturation monitoring. It was concluded from this study that there were many small vertical fractures, predominantly located in the dense limestone intervals, which gave rise to a strongly anisotropic reservoir transmissibility.

A study has been initiated to determine the best development scheme to recover oil and gas from two oil rim reservoirs off shore Abu Dhabi utilizing horizontal wells. One pilot horizontal well has already been drilled in the lower reservoir and few more are planned. Due to uncertainties in the fluid contacts and reservoir characteristics, a vertical pilot hole had to be drilled and cored to decide on the optimum location of the horizontal hole. A detailed core study was conducted to study the main rock types and lithofacies of this reservoir and a sector model was constructed to study the effect of different reservoir parameters on the performance of the horizontal well. PVT data from the gas cap and the oil rim will be used to construct an EOS that will be used in the full field compositional model. The results from this model and the performance of the pilot horizontal wells along with ongoing detailed geological study will help in determining the optimum development plan for these reservoirs.

Tt:te presence of natural fracturing in the Umm ShaH Thamama Field was postulated following its discovery in 1958. The performance of this reservoir was poorly understood being based on information gathered from a small number of well tests executed during the 1960's and 70's. An up to date assessment of this reservoir was sought utilising the latest reservoir monitoring technology. The objective was to confirm the existence, magnitude and orientation of any fracturing in the Thamama reservoir. A further objective was to evaluate their distribution within the zones of the Thamama reservoir. The surveillance programme included multi-well interference testing, pressure build-up testing, production logging and water saturation monitoring. The conclusions from this study were an unusually high kv/kh and strongly anisotropic reservoir transmissibility arising from the presence of fractures.