【本周专题：压裂增产】StackFRAC系列升级 专注小井眼增产作业难题

The Packers Plus StackFRAC? HD Slimhole system is specially designed with a smaller liner outside diameter (OD), enabling operators to re-enter vertical or horizontal wells. This system provides a cost-effective solution for restimulation and well recovery applications.

The Slimhole system was developed with the same features and efficiencies as the Packers Plus StackFRAC HD multi-stage completion system. This innovative system allows for exact placement of stimulation treatments in one continuous pumping operation, saving operators time and money.

The StackFRAC Slimhole system offers many features and benefits:

–Built on StackFRAC HD technology
–Continuous rigless pumping operation reduces completion time and cost
–Custom stimulation for each stage of a previously completed wellbore|
–Immediate flowback after stimulation

The StackFRAC Slimhole system can be used in many applications:

–Restimulation of existing vertical or horizontal wells completed with cemented liner or open hole multi-stage systems (OHMS) to improve recovery from damaged or depleted zones
–FracPORT sleeves can be aligned with existing ports to establish communication with the reservoir
–Recovery of wells where a loss of integrity has hindered the ability to stimulate
–FracPORT sleeves can be aligned with new or existing perforations to establish communication with the reservoir
–Field-proven RockSEAL packers isolate liner breaches enabling stimulation of the well
–Stimulation of open hole laterals drilled off of existing verticals to exploit new or depleted zones and increase productivity
–Saves on well construction costs associated with drilling and casing a new wellbore
–Eliminates the need to drill additional wells to exploit a reservoir
–Easily installed through high degree build sections

What the StackFRAC Slimhole system is made of

FracPORT H2 Sleeve

The FracPORT H2 sleeve is a ball-actuated, hydraulically activated injection/production port. This sleeve is run between two RockSEAL H2 packers to allow specific zones of the wellbore to be isolated and selectively stimulated. By providing a flow area greater than the liner, the FracPORT H2 sleeve provides unrestricted flow for stimulation treatments. The FracPORT H2 sleeve is also available in a Drillable Closeable (DC) version that can be closed or re-opened for future operations. This allows for effective water or gas shutoff, flow control, re-fracturing and production testing.

RockSEAL H2 Packer

The RockSEAL H2 packer is a hydraulically set, mechanical packer. The dual-element design, along with premium seal technology, ensures reliable high-pressure zonal isolation during stimulation and throughout the life of the well. The RockSEAL H2 packer offers ease of installation through its short length, minimum outside diameter and anti-preset features. Hydraulic activation allows for precise control over the setting operation, resulting in time and cost efficiencies.

Case Study 1

The Triassic Doig formation is located in northwest Alberta and stretches across the border to northeast British Columbia. The Doig is composed of siltstone and shale and overlies the Montney formation. A maximum thickness of 190 m (623 ft) is reached in the foothills of the Canadian Rockies and thins out towards the north and east. In northeast British Columbia, the Doig is the main producing interval of the Inga operating area. The reservoir is 25 to 30 m (82 to 98 ft) thick and contains an estimated 12 Bcf of gas and 4 million bbl of condensate in place per section of land. Reservoir characteristics make the Doig a prime candidate for horizontal drilling and multi-stage fracturing techniques.

A junior operator targeting the Doig formation in the Inga operational area planned to complete their 11-stage well using an open hole system. The operator was able to successfully stimulate the first six stages, but encountered operational difficulties due to a loss of integrity in the liner hanger packer, which prevented treatment of the remaining stages. Despite the original completion system being supplied by a competitor, the operator approached Packers Plus for an effective solution to recover the well that would allow them to successfully stimulate the remaining stages.

The operator chose to recover the remaining stages in the well with a 5-stage Packers Plus StackFRAC? Slimhole multi-stage fracturing system by installing it inside the existing open hole liner (Figure 1). The Slimhole system was developed with the same function as the field-proven StackFRAC system, but was specifically designed for applications that require a smaller liner outside diameter, such as re-entry into existing wells.

The 4.5 in. x 2.875 in. Slimhole system was designed with RockSEAL? ll packers equipped with elements engineered to provide effective isolation inside a liner. The breach at the existing liner hanger packer was flanked by a RockSEAL llS anchor packer above and RockSEAL ll packer below the damaged tool to achieve annular isolation. Prior to re-entry, the last five ball seats in the existing open hole system were milled out and perforations were created to allow for communication with the formation. During installation, FracPORT? sleeves were precisely aligned with the perforations, enabling the remaining stages to be stimulated. After the successful installation, the well was stimulated with a propane fracture treatment. The StackFRAC Slimhole system has multiple applications for operators working in formations which require completion and well recovery solutions. These include stimulation of open hole laterals drilled off of existing vertical wells to exploit new or existing producing zones; re-stimulation of existing cemented liner or open hole wells to improve recovery from damaged or depleted zones; and re-completion of cemented liner completed wells where a loss of casing integrity has hindered stimulation.

Case Study

Many operators are looking to increase production from older wells in mature reservoirs to maximize field recovery. A key strategy to accomplish this is to leverage new technology, such as multi-stage fracturing systems. An operator working in central Alberta was interested in re-stimulating a horizontal, cased hole well targeting the Glauconite formation of the Lower Cretaceous Mannville Group.

The well was over 10 years old and was originally completed with 4.5-in., 17.26 kg/m L-80 casing cemented to surface. There were two existing sets of perforation clusters from the initial stimulation treatment approximately 100 m (328 ft) apart, a third of the way into the 900 m (2,953 ft) lateral. To maximize the re-stimulation of this well, the operator wanted to shoot new perforation clusters to cover the entire lateral. Effective stimulation of these clusters would require a diversion method that would allow stimulation of the new perforation zones, as well as the ability produce from the existing perforations.

The solution involved designing a 4-stage StackFRAC? Slimhole system using a 2.875-in. liner to re-enter the original 4.5-in. cemented casing. Three new sets of perf clusters were shot approximately 150 to 300 m (492 to 984 ft) apart along the horizontal. FracPORT? sleeves were strategically placed for targeted fracture through the new perforations as well as to allow for production from the existing perforations. The system design included a Pump Out Plug and a RockSEAL? IIS packer, which provided added anchoring to frac out the perforation cluster located at the toe (Stage 1). The next three stages used two RockSEAL II packers and three FracPORT sleeves: two located at the same depth as the new perforations (Stage 2 and 4) and one set in the middle of the two existing sets of perforations (Stage 3). The StackFRAC Liner Hanger Packer served to isolate the top of the fourth stage.

The tools were run into the cased hole to the designed depth without incident. All FracPORT sleeves opened, demonstrated by spikes in the surface pressure gauge, and approximately 100 tonnes (220,462 lb) of proppant were successfully placed in the three treatment stages in one day. The initial 3-month production rate, not including the flowback period, was over 1,900 mcf/d. This equates to an increase of over 50 times the pre-frac rate and over 4 times the 3- month IP obtained from the original completion (Figure 1). In one year, re-stimulation with the StackFRAC system resulted in over 435,000 mcf of additional gas. These results demonstrate the utility of the Packers Plus StackFRAC system to increase production rates from previously completed, cased hole horizontal wells. This gives operators the opportunity to access untapped reserves to maximize their recovery from mature fields.