Traditional perforation jobs open the well bore to the flow of oil and gas, but they often leave behind debris that inhibits that flow. A new system developed by experts in oil and gas and weapons found a way to clean up that debris during the perforation treatment.

The answer lies in the ConneX Perforating system’s ReActive perforating technology partially financed through Shell’s GameChanger program, developed by QinetiQ in the United Kingdom and licensed to GEODynamics. The company plans to begin shipments of the new system in the third quarter this year.

Standard perforation
Typically, an operator drills a well, cases it and cements the well to isolate the producing

Figure 1. Perforation produced in Berea Sandstone at 2,000 psi effective stress and ambient well bore by conventional 33¼8 in., 25g HMX deep penetrating SDP shaped charge. (All photos courtesy of GEODynamics)
Figure 2. Perforation produced in Berea sandstone at 2,000 psi effective stress and ambient well bore by 33¼8 in., 25g HMX ConneX perforating shaped charge showing an improvement in perforation geometry.
sector. It reaches the oil or gas by using a shaped charge to shoot through the casing and cement into the formation.

That shaped-charge technique has been around for a long time. The military developed the charges for bazookas to pierce tank armor during World War II, and it came to the oilpatch in the 1950s. It has been the workhorse of perforation ever since, according to Matt Bell, vice president of technology for GEODynamics.

Now the industry has reached the point that it can’t get much deeper into the formation with conventional shaped charges. In addition, conventional charges leave a significant amount of loose debris in the perforation tunnel and line the tunnel wall with crushed materials.

Cleanup
If the operator can clean out that debris and crushed material, it gets good recovery from the well, he said. If the cleanup doesn’t work well, the debris blocks part of the potential recovery from each perforation.

The industry has put a lot of work into getting rid of that debris, he added. It has tried static balance, underbalanced drilling, pump treatments to wash away or dissolve the debris, water fracs, jetting tools and high-pressure gas propellant.

Each step in the cleanup procedure adds more cost to the well, and often, particularly in heterogeneous reservoirs, those efforts don’t work as well as the operator hopes.
Ideally, he said, the operator wants:
• 100% perforation efficiency for more inflow to the well bore;
• a step-change in flow performance; and
• all zones to contribute to the total well flow.

New system
QinetiQ, Shell and GEODynamics put approximately 3 years of work into developing a system that could satisfy those operator desires.

The ConneX perforating system removes the crush zone from the perforation operation and removes the loose fill around the perforation tunnel.

That crush zone affects more than the flow of hydrocarbons into the well bore. It also could dilute the effectiveness of injection of water, gas, acid, proppant-packed gels for fracture treatments and fluids that move gravel for sand control in unconsolidated formations.

Performance
Nathan Clark, vice president of ballistics engineering at GEODynamics, offered examples of
Figure 3. Perforation in Berea sandstone at 5,300 psi overburden, 1,500 psi pore pressure, and 1,000 psi well bore pressure by conventional 33¼8 in., 25g HMX deep penetrating SDP shaped charge.
Figure 4. Perforation produced in Berea sandstone at 5,300 psi overburden, 1,500 psi pore pressure, and 1,000 psi well bore pressure by 33¼8 in., 25g HMX ConneX perforating shaped charge — 30% improvement in flow performance.
the improved performance. In a moderate-stress formation, he said, a conventional shot will penetrate 13 in. and leave debris in the tunnel. In the same situation, the ConneX systems will penetrate to 14 in. with 100% cleanup and offer a 30% better production rate.

In a high-stress formation, both the conventional and the ConneX system will penetrate to 9 in., he added, but the new system offers a 20 to 40% better inflow than the standard system and the operator doesn’t have to underbalance the well to clean up the debris.

The company offered an example of the advantage of the ConneX system over conventional charges when set off in tests in the Berea sandstone.

Results included:
• 44% more clear tunnel depth;
• 164% more tunnel surface area;
• 355% more tunnel volume; and
• 35% improvement in flow performance.

During a question and answer period at the company’s introduction of the system, Bell said, the ConneX system also creates debris, but it forces the debris back into the well bore. The system effectively generates pressure in the tunnel to push the debris out.

Details
Taking a closer look at the details of a perforation, the charge includes primer, an outer case, explosive and a conical liner that helps maximize penetration. When the operator sets off the charge, the line collapses and forms a high-velocity jet of fluidized metal particles that it punches through the casing and cement into the formation. The initial velocity of the jet is approximately 30,000 ft/second.

That explosion shoots steel, cement, rock and well bore fluids into the formation with such force that it pulverizes the rock around the tunnel and leaves a zone of crushed rock in the tunnel. The combination inhibits the tunnel’s ability to accept flows in either direction.

In some prolific reservoirs the pressure of the oil or gas flow will clean up the tunnel, but most formation pressures aren’t that strong. Operators compensate for the lack of natural cleanup by using acid stimulation, brine wash, hydraulic fracturing, hydro-jet tools, Stimgun or StimTube propellants, and static or dynamic underbalanced drilling and completion. Even filters and magnets have been developed to help with the cleanup operation.

The ideal perforation operation would give an operation 100% cleanup in any kind of formation and offer 100% flow efficiency both in and out of the tunnel. It would allow full flow throughout the well bore and it would increase ultimate recovery from the well.

The ConneX system works in the same way as the conventional charge but with an added reaction at the end of the perforation treatment. It even fits in conventional perforating guns without modification. It is compatible with conventional perforating procedures. The operator or service company won’t have to change handling, shipping or operating procedures to obtain better results. The outer case even looks like a conventional charge.

The difference lies in the materials in the ConneX system. “The system releases energy from the reaction between materials,” said Prof. Mike Hinton, technical director for QinetiQ. When the gun is detonated, the system creates a heat-releasing Hume-Rothery intermetallic reaction between the components of the liner, initiated by the shock of detonation to create a secondary reaction in the perforation tunnel. That reaction comes from a new liner technology using a controlled combination of bimetallic liner material pressed under controlled conditions. The reactive properties of the system create high lateral pressures in the tunnels and force the debris out of the tunnel and back into the well bore.

Although sales won’t officially begin until the third quarter this year, Clark said, several companies are interested in running the treatments. The company already has scheduled trials of the system in Europe and North America.

Asked about the cost of the system, Bell said adding to the shape charge adds to the cost of the charge, but the benefits of the system should add value for the user.

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