Integrated Fracture Study using Formation Micro Imager, Stoneley Waves and Formation Evaluation Results in Carbonate Reservoir at Gulf of Suez, Egypt

摘要

The carbonate reservoirs in Gulf of Suez area have complex geological structure due to the existence of fractures associated with faults. Thus, fracture characterization of this complicated area is very important to understand the reservoir behavior and hence assigning the best completion intervals for the producing wells. In this paper, we developed a workflow of integrating formation micro imager, Stoneley waves and petrophysical analysis for better fracture characterization and selecting the best perforation intervals for a producing well. This workflow is applied on well NWO-1, in the Northwest October Concession in the Gulf of Suez area over the carbonate reservoir. The well was drilled on the peak of anticlinal feature created by fault propagation fold of a normal fault that located nearby the well. The main objective was to determine the structural geology features (i.e. fractures), its orientation and the diagenetic features (i.e. vugs) using formation micro imaging tool. Also, to quantify the effectiveness of fractures as fluid conduit mainly in the carbonate reservoirs either in Thebes or Mokattam Formation via Stoneley waves derived from processing result of sonic measurement. This is combined with the petrophysical interpretation using the elemental spectral device data and other conventional open hole logs to provide a comprehensive petrophysical formation evaluation. The study reveals that the highest average fracture density is over (Layer-A & B) at the upper most interval of Thebes Formation around 2.2 fractures/ft and (Layer-C) at the bottom around 1.77 fractures/ft. These fractures were proved to be of good fluid conduit based on both Stoneley waves and the petrophysical interpretation. The two layers A and B were recommended to be tested and the DST (Drill Steam Test) results proved the higher productivity than layer C which confirms the outcome from our integrated study.