The traditional approach to perforating placement in horizontal wells with geometrically spaced perforating clusters and stages does not take into account toe-to-heel heterogeneity and often results in a number of perforation clusters that do not contribute to well performance. Production logging data has shown that as much as 40% of perforations may not adequately accept treating fluid, resulting in non-optimized stimulation of the targeted reservoir.
To improve well stimulation and productivity, GR Energy Services offers the PerfTactix* 5-step program, which utilizes drilling, mud logging and formation evaluation data to optimize completions. The resulting answer product precisely positions stages and perforation clusters along the wellbore by targeting rock with similar geomechanical and producibility properties. The program selects the ideal stage spacing, perforation cluster placement, and shaped charge and gun system design to ensure higher-payback hydraulic fracturing operations. Highly efficient plug-n-perf field execution and post-frac monitoring provide unmatched performance compared to traditional approaches.
Completion engineers who utilize the PerfTactix methodology will realize improved well completion and production results through:
- Targeting rock with similar properties within the stage to achieve more even proppant distribution across all perforation clusters, which leads to enhanced production
- Improving formation breakdown and decreasing the chance of screen-out by placing perforations in consistent rock and selecting appropriate shaped charges for fracture treatment
- Optimizing the perforating system to improve delivery and fracturing performance
- Continuous improvement of wellsite operations and future frac designs.
The PerfTactix answer product takes the guesswork out of stage length and perforation cluster placement decisions to improve the effectiveness of hydraulic fracture operations.
5-step PerfTactix method
The PerfTactix five-step method varies with well complexity and value. When all five steps are employed, a closed-loop optimization process can be achieved by
- Evaluating perforation cluster placement
- Selecting shaped charges and gun phasing to ensure a better frac
- Choosing the components required for an ultra-efficient gun system
- Executing a highly efficient wellsite operation
- Diagnosing well profiles cost effectively during production.
1 – Data capture
Openhole formation evaluation data are essential inputs to engineer better completions. The Logging-While-Tripping (LWT†) tool, an innovative logging technique, enables efficient acquisition, in a horizontal lateral, of gamma ray, spectral gamma ray, compensated neutron, compensated formation density and dual induction data. This information is recorded during normal drilling operations with virtually no additional rig time. Drilling data (WOB, RPM, ROP, torque and MWD/GR) and mud logging data can be integrated with LWT data to enhance the analysis.
†LWT is a trademark of Cordax Evaluation Technologies Inc.
2 – Data analysis
Zone Grader† analysis of the well data is used to evaluate the optimal placement of perforation clusters. This unique answer product grades the formation along the wellbore based on geomechanical and producibility formation characteristics. Geomechanical rock properties include stress, brittleness and lithology. Producibility properties include lithology, total organic carbon (TOC), porosity, permeability and saturation. With the wellbore graded by geomechanical and producibility properties, the number and position of stages can be determined and perforation clusters precisely placed.
†Zone Grader is a trademark of Cordax Evaluation Technologies Inc.
3 – Perforating design
Perforation geometry is a key element of designing an optimal completion. Not only should perforation clusters be tactically positioned along the lateral, but shaped charge selection based on perforating geometry should be considered to properly treat the well per the design. Consistent perforation entrance hole (EH) diameters are a vital component of optimizing fracturing efficiency. Perforating EH diameters must be large enough to prevent proppant bridging and consistent in size for accurate limited-entry designs. With conventional 60-degree systems, a 40% variation in EH can result in a 120% increase in pressure drop. By utilizing consistent entrance hole charges, completion engineers benefit from perforation clusters accepting treatment fluid according to the design because a greater number of holes are open, providing a consistent pressure drop across all perforations. Enhanced liner perforating charges provide increased perforation tunnel diameters to the formation, which reduce breakdown and treating pressures (less horsepower required and thus cost) and improve access to the formation via tip fractures.
4 – High-efficiency field execution
An ultra-efficient plug-and-play gun system is used to ensure the safest, most efficient completion time possible. The system uses state-of-the-art, inherently safe switches to eliminate the risk of surface detonation and to enable gun skipping downhole in the unlikely event of a misfire. Unlike conventional gun systems that require up to 100 manual connections to arm the guns, there are no wires, so field assembly times are much faster and the chance of human error is significantly reduced. ZipLok* equipment makes rigging up and down more efficient while adding unmatched safety measures to protect wellsite teams from injury. Run-in-hole safety is optimized using modeling software that indicates when downhole tension and release tools are required to reduce risk. Each component of the system is chosen to achieve the safest, most reliable, fastest plug-n-perf operation.
5 – Monitoring
After flowback, Diagnostix* fiber optic monitoring services can be efficiently deployed to record distributed temperature (DTS) and acoustic (DAS) surveys. Unlike traditional production logs, the entire wellbore can be simultaneously surveyed in real time to detect and monitor contribution of each perforation cluster. Results of the production profiling are used to optimize future stimulation programs and to consider the potential benefits of refrac programs.