The trajectory placement of a horizontal well that crosses a heterogeneous tight gas carbonate reservoir is one of the important elements that contribute to the success of well productivity. Proper placement can yield good production and vice versa improper placement may give low well productivity. An effort was studied to improve the well productivity from an existing single horizontal well that was initially placed in sub optimal location by implementing the Fishbones completion technology (work-over).

In this paper, Simulation Opportunity Index (SOI) has been selected as a method to indicate the remaining gas sweet spot throughout the reservoir. SOI integrates 3 independent components extracted from static and dynamic parameters; reservoir permeability-thickness, movable gas, and reservoir pressure from a historically-matched dynamic model. By utilizing SOI, a map of the prospective gas sweet spots can be created; hence low performance existing wells are utilized to exploit the surrounding potential sweet spots using Fishbones completion, which consists of tiny short needles with a maximum effective length of 32 feet placed along the horizontal section.

The study reveals that the Fishbones completion application on existing low-productive horizontal well can multiply the well productivity in multi-layer reservoir environment in addition to the significant production gain. Assisted History Matching (AHM) is used to explore the best scenario of Fishbones features combination, such as the number of Subs required as the container room to hold the needles, the optimum needles length, and the optimum lateral drain section to place the Subs and needles. Many sensitivities with the abovementioned variables are run at once, and the analysis is conducted to identify the most impacting parameter to bring the highest well recovery. The use of SOI method to scrutinize the best location of well candidatures for Fishbone application and the required Subs and needles placement is not only able to rejuvenate the performance of the problematic well, but it can aid in generating CAPEX saving and efficient project schedule to manufacture Fishbones with a proper number of Subs and needles compared to blind Fishbone technology installation.

A combination of two techniques between reservoir simulation study to generate SOI with the new advanced completion technology called Fishbones applied on low-performance existing horizontal well is the real study integration with the final objective to increase the ultimate gas recovery in a tight gas carbonate reservoir. This is a breakthrough solution to optimize the development of tight carbonate gas fields in addition to the conventional development strategy with normal infill drillings.

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