Advances in technology are pushing the boundaries of what is possible with wireline cable conveyance with heavy payloads. New high-strength cables, conveyance systems, wireline tractors, prejob modeling software, and a wide range of additional enabling technologies have shifted the conventional norm for wireline perforating applications, thereby allowing for the successful shooting of very long perforating gun strings. Detailed job planning is required and, with the help of conveyance planning and shock modeling, perforating bottomhole assemblies can be optimized and maximized payloads of perforating guns can be run. Successful operations have been completed in which 100 ft or more of perforating guns from 2 7/8-in. to 7-in. have been deployed and shot in a single descent in many areas including Qatar, Oman, UK, Norway, Mexico, and Brazil. Combining the new hardware breakthroughs with advanced software modeling has enabled the implementation of ultralong and heavy wireline perforating jobs in both offshore and land operations. These new wireline perforating techniques have improved efficiency and logistics while reducing rig time and cost; they will be of interest to all operators conducting perforating operations.

We present a new perforating technology based on new wireline conveyance equipment and advanced downhole modeling to maximize operational efficiency in long pay-zones under all pressure conditions. Results of perforating jobs of long pay-zones carried out on wireline in very short times compete with traditional Tubing Conveyed Perforation (TCP) operations which take much more time. Also, perforating jobs with large gun sizes that until recently were not possible in a single run with traditional wireline conveyance, are now efficiently executed in a single run. The new technology that allows conveying long lengths of perforating guns on wireline in a single run is based on four main elements: wireline systems with safe working loads up to 30,000 lbf, cutting-edge shock resistant mechanical weak points and disconnect systems, conveyance modeling, and an advanced transient dynamic modeling for perforating shock prediction. The perforating job design modeling is based on the reservoir zones and completion information, both a conveyance and a wellbore dynamics and shock simulation are carried out to determine the highest payload that can be more safely deployed per wireline run, and with the number of runs required, costs and risks are compared between wireline and TCP shoot and pull operations. For a well with a 750 ft thick pay zone, a North Sea operator requested a comparison between this new wireline perforating technology and conventional electric wireline deployment in terms of reservoir productivity, risks, and operational performance. For this well TCP was not considered due to reservoir and operational risks and challenges. Compared to the conventional electric wireline conveyance this new perforating technology offers better efficiency with only two wireline runs using a cable with 18,000 lbf of safe working load and a 10 Kpsi surface pressure control equipment compared to 6 to 8 conventional runs. The longest run consisted of 388 ft of 3 3/8″ guns, which was a new world record on wireline, with energetic liner charges and dynamic underbalance to ensure maximum perforation tunnel cleanup and well productivity. The total operational time for the perforating job was significantly less than conventional electric wireline, which translated into significant rig time savings. This paper demonstrates how the application of innovative technologies have minimized the risks of wireline conveyance with long and heavy perforating gun strings. We utilized well and reservoir information to design a more safe and reliable job execution, including prediction of perforating shock, tension profiles and wellbore dynamics. The new perforating technologies described in this paper have extended considerably the range of perforating jobs where wireline conveyance can be more efficient than traditional coiled tubing and tubing conveyed perforating.

This paper presents field results of the first well perforating system integrated with a depth correlation and real time high-speed measurements device, this tool acquires and transmits downhole data to surface in real time while perforating. The docking gun system with plug-in design improves operational safety, efficiency and reliability, whereas downhole measurements help to obtain maximum well productivity by providing real-time downhole wellbore pressure, transient dynamic underbalance and/or overbalance for perforation cleanup and/or well stimulation. The new perforating system consists of two main components: a docking gun system and an advanced measurements module. The docking gun system consists of a compact, plug-in, radio frequency safe, addressable firing system for single and multi-zone sequential perforating applications. The system eliminates port plugs and wellsite arming of detonators, reducing human error and improving overall safety, efficiency, and reliability. The advanced measurements module provides high-frequency transient wellbore pressure, peak acceleration amplitude, and low frequency pressure, temperature, gamma ray, and active casing collar locator. These measurements enable real time confirmation of downhole conditions before, during, and after perforating, with accurate depth correlation even in high chrome tubulars and large casing sizes. This instrumented docking gun system delivered an outstanding field performance, adding value to operators by increasing safety, efficiency and reliability, while at the same time maximizing productivity. This instrumented gun system can be deployed with wireline, tractor or electrical coil tubing. The new docking gun system design reduces human error and the risk of wellsite accidents and failures. With this system we also maximize gun length deployment per run and operational efficiency. In addition, real time downhole measurements of low- and high-frequency wellbore pressure allow optimization of perforating cleanup and stimulation, maximizing productivity and reducing the overall cost per barrel produced.

Technology Update Accidental detonation of a perforating gun at surface can have catastrophic consequences. To decrease risks, layers of procedural controls have been implemented to reduce the inadvertent application of power caused by human error, stray voltage, or the presence of radio frequency (RF) energy. Explosives handling procedures and controls, such as locking out the firing panel and acquisition system, are used to mitigate the human error risk. Mitigating RF risks requires establishing RF-free exclusion zones, with all RF transmissions shut down. Exclusion zones are effective, but adhering to them relies on strict procedural controls. With increased industry and personal reliance on RF transmitters, such as cellular phones, RF silence is becoming more difficult to achieve. Although RF-immune initiators were introduced more than 20 years ago to allow wellsite operations to continue without RF silence imposed, their complex initiation technologies require high power levels, which improve the safety margin to stray volt-age but significantly reduce overall system reliability. Perforating has always been a hands-on operation that relies on supervisor experience. Over the last decade, perforating reliability has continued to improve as service companies and operators have implemented detailed training programs, procedural checklists, and advanced hardware. However, these reliability improvements have begun to plateau, acting as an impetus to develop new perforating systems that would be more effective than procedural controls in addressing the main causes of perforating misruns: damaged or improper wiring, mechanical seal failures, and initiator malfunctions. Plug-In Design With Built-In Safety With a focus on resolving these issues, Schlumberger developed the Tempo instrumented docking perforating gun system—the industry’s first perforating system that fully integrates a plug-in gun with real-time advanced downhole measurements for monitoring and confirming operations to mitigate risk while increasing safety, reliability, and efficiency (Fig. 1). Created for all environments, the system uses modularized initiators combined with RF filtering mechanisms and an addressable switch to provide an enhanced level of safety to operations. Proprietary docking components are the key element of the gun system’s plug-in design. They streamline assembly and eliminate the major cause of perforating misfires: technique-sensitive crimping and wiring. The initiator can be plugged into a perforating gun by using simple mechanical and electrical connections without requiring complicated assembly. The new system eliminates all complex field wiring connections and crimping, which simplifies the arming process that has a direct impact on both wellsite efficiency and reliability.

No abstract