Pre-post frac test data analysis for hydraulically fractured vertical tight oil well- Field case study

Introduction: Reservoir Hydraulic fracture stimulation practice has proved to be a success to create highly conductive channels in the formations having very low permeability values as well as improving well hydrocarbon recovery across the united State and Europe for decades.

This technology became an essential application in North Africa particularly (Sirte Basin) after the discovery of deep tight sandstone reservoirs.

The aim of this study is to assess a tight sandstone reservoir formation before and after hydraulic fracture treatment and the magnitude of the productivity enhancement and recovery increment.

Method and/or Theory: An effective hydraulic fracturing design is a key to achieve the expected results in low permeability reservoirs. All relevant available static and dynamic data were gathered to optimize the fracking input parameters and two and three dimensional models were developed in the three candidate oil wells (x1, x2, x3) in north Gialo field (Sirt Basin) operated by Waha Oil Company.

In addition, there was also formation evaluation and dynamic data analysis (DDA) before and after the fracking operation process to assess the treatment potential and the overall success in percentage for each well.
Results, Observations, Conclusions: In conclusion, the hydraulic fracture can be considered as a very successful stimulation job practically and economically for low permeability sandstone reservoirs with an increase of well flow rate of ten fold increase.

Novel/Additive Information: Based on data analysis, the oil production rate of the three selected oil wells is improved dramatically by four to ten times with a significant decrease in the formation damage near the wellbore. The success of the frac. treatment is largely due to efficient candidate selection, project management, and systematic application of existing hydraulic fracturing techniques.

Figure 1 Shows the final profiles used with current XX-4 target perforation intervals.

Keywords: Tight reservoir, Hydraulic Fracturing, Pre-post frac, Nubian Sandstone Reservoir, well Productivity and oil recovery, open hole logs, FMI/OMI-UBI logs, Dipole sonic log.

Acknowledgements: The authors would like to thank Waha Oil Company especially planning department and National Oil Cooperation of Libya for giving permission to publish this work.