Abstract
The design of an optimal and effective hydraulic fracture treatment requires lots of input data, spanning the spectrum from rock properties, fluid properties, well-logs, Geomechanics to economics. However, operators tend to cut costs by reducing expenditure on data acquisition. This paper discusses the challenges of hydraulic fracture treatment design in such cases and presents procedures that can be used to effectively design fracture treatments where completion engineers may not find the needed data from obvious direct sources. Recommended solutions for obtaining data from indirect sources to fill the gap of unavailable data are presented. In addition, the adequacy of such designs is evaluated and compared to actual hydraulic fracturing treatments pumped.
Treatment designs pumped for several stages of a fractured well located in the Permian Basin of West Texas, US were investigated. This is a geologically complex environment with huge variation in lithology and formation properties. The well under study had only the drilling records and the conventional logs suite (gamma ray, neutron, density, pe and resistivity). However, to finalize other required data for the treatment design i.e. reservoir permeability, geomechanical properties, etc., the design inputs were obtained through the creation of synthetic logs. Sonic logs were generated using models created from log data from off-set wells. In addition, geological properties of the candidate formation were reviewed and used for data calibration. These collected data were then used in designing the hydraulic fracture treatment using industry standard fracture design software, FRACPRO, to obtain the design outcomes. The treatment was designed and simulated using the same fluid systems and proppants as was used in the actual pumped treatments. Finally, the design results were compared to the field treatment data from the fractured well.
Compared to real-time fracturing results, the pressure and rate profiles were close match to those generated by the software. This shows the possibility of conducting a proper fracturing design using limited acquired data. However, these results depend mainly on the accuracy of the well logs used to generate the mechanical properties, and the available data about the formation from previous treatments. Moreover, the accuracy of fracturing simulation when all needed data are obtained by direct measurements should be compared to situations with paucity of data, to determine how to improve the results obtained.
The information presented in this work will help engineers deliver economic and optimal hydraulic fracture treatments especially in this present low oil price regime. Also, informed and appropriate decisions can be made regarding optimized data acquisition in candidate formations for better planning and maximum profitability.
