Drill stem test (DST) derived average effective permeability and productivity is our industry's accepted standard but DST expenses are not always justified especially in development wells. Although zonal contribution could be measured by production logging survey but this requires an additional well intervention operation and most likely interruption of production as well. Zonal productivity modeled correctly in a well is of immense value for reservoir management. In exploration well, accurate productivity index prior to DST is invaluable for operational planning, while in development well accurate productivity index is crucial for completion design.If dynamic data is not available, zonal productivity had been estimated based on permeability derived from petrophysical log data. Single probe open-hole wireline formation tester (OH-WFT) pretest mobility is often used to calibrate log data estimated permeability. However, OH-WFT pretest almost always measure the invaded or drilling induced damaged zone and is at a scale much smaller than DST derived average permeability. DST 1699.36 -1699.5 m WFT 1707.5 m Pretest and Sampling DST 1699.36 -1699.5 m DST 1699.36 -1699.5 m WFT 1707.5 m Pretest and Sampling

Recently, there has been an increased interest in optimizing horizontal multi-frac completion technologies used to complete offshore low permeability reservoirs in Western South China Sea, but the high-risk and high operating costs are the key problems to hold back the application of this technology, so the impact of economic factors should be taken into full account before fracturing design. This paper shows an new optimization approach of fracturing design by considering the relationship between economic aspects, reservoir size and fracturing treatment size, each fracturing stage of horizontal well is approximated by a rectangular drainage areas and the unified fracture design method is used to calculate the dimensionless productivity index, and an Optimal Proppant Index Function is established with maximization of economic profit as the objective function, while the Optimal Proppant Index Function is determined, the optimal fracture volume and parameters would be obtained.

Considering the variable-permeability effect of non-Darcy flow in low-permeability reservoirs, this work set up a two-dimensional model with boundaries. The implicit finite difference algorithm was employed to solve the well test model, and typical curves in log-log scale by considering the effects of variable-permeability and non-Darcy flow were obtained. The results show that, in reservoirs with impermeable boundary, the upturned part of the pressure derivative curve caused by boundary effect will be covered by that of non-Darcy effect, indicating boundary effect is postponed to appear. The more of the non-Darcy effects result in less obvious upturn of the typical curves. The upturn of typical curves and the effect of boundary are enhanced by increasing the numbers of impermeable boundaries or by decreasing the distance from the well to the boundary.