This paper discusses the early evaluation of vertical connectivity with vertical interference tests (VITs) using an advanced multi-probe wireline formation tester in a giant carbonate field in Saudi Arabia. The objective was to determine the vertical permeability of low permeability layers within the reservoir. Early understanding of the vertical connectivity is required to ensure the optimum development for new fields with limited dynamic data. To conduct the evaluation, a multi-probe advanced formation tester was utilized in five key wells around the field to obtain vertical and horizontal permeabilities with several VITs creating pressure pulses at the dual packer, which produce pressure responses monitored at the two observation probes in real time. The vertical connectivity was assessed from the pressure response to the transient generated across stratigraphic layers. Comprehensive interference tests were conducted across all the layers. Advanced nonlinear regression analysis techniques were utilized for pressure transient analysis at test intervals. The results were further confirmed with a fine gridded 3D reservoir simulator. The integration of all vertical permeability results obtained so far indicated a good degree of reservoir vertical connectivity. The VIT results were used as input in the field simulation model improving the accuracy of the vertical permeability in different areas of the reservoir, which in turn supported changes in the well placement strategy to maximize recovery.

Flow profiles of horizontal wells in heterogeneous or fractured reservoirs are usually nonuniform and are frequently characterized by high flow capacity from streaks in high permeable zones or fractures. The nonuniform flow usually causes early water breakthrough that ultimately undermines well productivity. In homogeneous reservoirs, water (or gas) breakthrough commonly occurs at the heel of the lateral section. In either case, whether in homogeneous or heterogeneous reservoirs, achieving uniform flow along the wellbore in horizontal wells to improve sweep efficiency and maximize oil recovery, requires application of advanced well completions that are guided by effective reservoir evaluation and management practices.Optimizing inflow profiles in horizontal wells requires good understanding of multiphase flow mechanisms, where the flow regimes are usually complicated due to stratification, slug flow, mist flow and/or other complex flow behaviors. Achieving better understanding of this multiphase flow mechanism was facilitated with the availability of the multiphase production logging tool (MPLT), which has been utilized extensively in this case study. This paper presents a summary of the results of a case study of 31 horizontal wells completed in a large carbonate onshore field, with the main objective to improve understanding of horizontal well inflow profiles and performance. For this case study, the areas of focus are inflow profile types, production performance and temperature log response. This paper concludes with lessons learned and practical recommendations to be considered for field development.