In order to increase well performance, two operators (“Operators”) selected Quantico Energy Solutions (“QES”) to provide horizontal well log data for completion projects in the Wolfcamp formation in Reeves County and in the Eagleford formation in Karnes County, both in Texas. The Operators’ objective was to optimize the effectiveness of the fracture treatment by maximizing the number of perforations that contribute to effective stimulation, thus increasing the stimulated reservoir volume for the stage. More perforation clusters stimulated effectively should lead to increased production. The challenge was to determine the geomechanical variability along the lateral wellbore so perforation clusters could be placed according to key parameters such as minimum horizontal stress (Sh-min).
Conventional open-hole logging solutions would have incurred over $150,000 in today’s market conditions. Mud logging and cuttings data provide a geological/lithological description of the wellbore, but do not address the rock mechanics issues. The performance of the QES engineered perforation cluster depth locations were evaluated using production data and analysis of the pressure pumping data.
QES provided an array of geomechanical logs (“QFrac”) that were derived from the drilling data from both wells which enabled savings of 80% to the Operator when compared to the cost of conventional e-line small diameter tool string pump down logging operations. The QFrac logs were generated within a few days of receiving the existing drilling data from the Operators, which allowed sufficient time for the Operators to review the QES recommendation and communicate plans to the service companies for the upcoming wellsite operations. The necessary datasets were integrated as standard well log presentations and associated digital data files. QES’ solution did not require any tools to be placed into the wellbore thus reducing lost-in-hole and operational risk for the Operator.
QFrac provided an array of geomechanical properties, presented in a well log format upon which decisions to optimize perforation cluster placement were based. The stage locations remained geometric consistent with prior practices. These optimized perforation cluster placements took into consideration Sh-min, a key parameter that affects the quality of the hydraulic stimulation treatment.
The Eagleford well and the Wolfcamp well were designed with 21 and 29 planned stages, respectively – the same stage spacing as employed in nearby wells by the two Operators. The control and optimized wells in the Eagleford and in the Wolfcamp employed the same stage spacing, perforation cluster count per stage, treatment schedule and were in the same formation. In the Eagleford, the two wells were located on the same pad. In the Permian, the two wells were located one mile apart.
QFrac was able to identify Sh-min values at each perforation cluster. A Stress Contrast metric was calculated to show for each stage the difference in Sh-min corresponding to the perforation cluster depths that exhibited the highest and lowest Sh-min. In the control well, perforation clusters were placed geometrically. In the optimized well, perforation clusters were located at depths that minimized Stress Contrast (SPE 181273). The Stress Contrast data from the Wolfcamp wells is shown in figure above.
The 60-day and 90-day production data was analyzed for the two well pairs (see Figures 2 and 3). The two studies concluded that relative to the control wells, the wells that employed the optimized perforation placement from QES had increased production of 9% and 27%.
Figure 1. Eagleford Well 60-Day Cumulative Production Relative to Well on Same Pad
Figure 2. Permian Well 90-Day Cumulative Production Relative to Well One Mile Away
QES provided the Operator with critical formation data for this horizontal well that would have been cost prohibitive to log using conventional methods. By placing the perforations in areas of similar stress, the stress contrasts were significantly reduced for each stage compared to the geometric design typically implemented when little or no horizontal data is available. The optimized perforation placement resulted in more effective stimulated reservoir volume and significant increase in production.
Increased production delivered to Operators
The production data was normalized to a 5,000 ft lateral section since there were variation in the lateral length of the completed/stimulated intervals between the Eagleford and Wolfcamp wells. The 60 day production comparison for the Eagleford wells are shown in the following table:
The 90 day production comparison for the Permian wells are shown in the following table:
The QES optimization of perforation cluster location to minimize stress variation for each stage shows significant increases in revenue to the Operator without the expense or risk of conventional logging operations. The payback period for QFrac is as short as a few days. Additionally, the Operators were satisfied that optimizing the depths of the perforation clusters without moving stage packers presented minimal operational or production risk to the overall completion programs.