水平井等非常规井已经彻底改变了石油工业，并从根本上改变了射孔技术。等孔径射孔技术已经证明非常成功并且已成为行业标准。随着非常规油井产量的下降，运营公司面临着对油井进行重新完井及重复压裂的挑战， Core Lab / Owen通过ReFRAC射孔技术来应对这一挑战。需要对重复压裂的油井进行机械封隔，由于现有油井采用套管完井，套管用水泥胶结，如果要保证射孔的一致性，复杂程度将成倍的提高。压裂措施将更加困难，进度缓慢，成本升高。ReFRAC射孔技术通过产生最佳的等孔径射孔以应对这些挑战。两个主要的运营商应用该技术后，压裂速度提高两到三倍，射孔次数也相应减少。单井时间成本和经济成本显著减少，利润率显著增加。多个运营商在重新完井措施中要求使用ReFRAC射孔技术。
图1 ReFRAC射孔弹射穿两层套管形成一排一致的孔眼。 （来源：Core Lab/Owen）
DynaEnergetics DS Trinity射孔系统在单个平面（三个共面）中设置三个射孔弹，以缩短射孔枪长度便于在重复压裂过程中更好压裂地层。新系统射孔枪总长度小于8英寸，比传统射孔枪短3.5倍，每级可实现更高的射孔数量。较短的射孔枪长度降低了起重机和压力控制设备的高度要求，因此节省了运行成本。已确定单平面射孔结构可降低地层破裂压力并实现最佳的射孔速率，因此可以减少压裂设备的磨损。此外，单平面射孔可以在某些地层中产生更好的裂缝形状，从而提高单井产量。最近完成的现场试验是与美国一家大型独立运营商合作进行，该运营商提供了有关该系统一些关键特性和功能的反馈。在现场试验过程中交付了1000多支射孔枪，射孔成功率100％。
图2 Dynaenertics DS Trinity单平面射孔系统比传统射孔枪短3.5倍。(来源:DynaEnergetics)
图3 图中显示了Kraken工具在井中的剖面图。(来源: Enhanced Energetics)
Nine Energy Service的FlowGun工艺技术是一体化无介质套管输送射孔工具，无需运行电缆或连续油管（CT），无需电子点火。FlowGun作为一体化完井技术一部分，具有创新、安全和经济的优势。它提供较高的效率、控制性和灵活性。使用FlowGun技术，操作员可以节省更多的时间和作业费，因为许多井下作业被整合到一个工具中，工作人员无需更换套管，无需电子点火。整个完井阶段被简化，无需为了额外的水、卡车及BOP租赁、CT、化学品和劳动力支付额外的费用。
虽然它是一种非常广泛使用的完井方法，但塞子和钻孔会对近井眼渗透率产生负面影响，因为射孔弹的冲击应力会削弱岩石基质强度并增加产砂的风险。National Oilwell Varco（NOV）的i-Frac系统帮助作业者规避使用常规射孔方法、射孔弹及射孔枪所产生的固有风险。 i-Frac是一种利用液压操作的滑动套筒工具，作为生产套管的一部分进行螺纹加工。使用球或线圈输送工具，套筒是可移动的，孔眼从内部暴露于内管中；在外面，孔眼被水泥覆盖。此后，压力增加射开水泥环并与地层连通。单个压裂段可以包含多达20个i-Frac套筒，通过投一个球就可以激发所有套筒并封隔该段区域以进行压裂处理。
图4 i型压裂套管是一种投球式多级压裂套管，适用于固井、多段开/关井和裸眼水平井完井。(来源: NOV)
Innovative technology designs are increasing efficiencies.
PERFORATING SYSTEMS TECHNOLOGY SHOWCASE:
Operators are constantly searching for the latest innovations to maximize production. The following technologies are some of the latest products and services available to the industry.
Perforating tool simulates and predicts dynamic conditions Built on advanced analysis and job planning data, Baker Hughes, a GE company’s (BHGE) TerraConnect perforating technology, engineered for reservoir conditions, simulates and predicts the dynamic conditions that occur during perforating events (See image above). These simulations predict transient behavior during laboratory testing, translating to optimum job designs that improve downhole results and reservoir contact. Using its PulsFrac software, BHGE optimizes perforation tunnel cleanup with a variety of technologies, including TerraFORM dynamic underbalance optimization services, TerraPERM propellant perforating optimization services and static underbalance techniques. The TerraConnect perforating technology and PulsFrac software provide a perforating design and cleanup operations optimized for the target reservoir. TerraConnect was recently applied on a multiwell project in Southeast Asia where laboratory test results led to product and deployment technique selection. Collaboration with the operator led to continual operational and production improvement over the course of the project, contributing to the ultimate reduction of wells planned by 33%.
Consistent hole size perforating
Horizontal, unconventional wells have revolutionized the industry and fundamentally changed perforating. Consistent hole size perforating has proven highly successful and has become the standard. As production on unconventional wells declines, operating companies are challenged to revitalize these assets through recompletion or refrac methods. Core Lab/Owen has delivered ReFRAC technology to meet this challenge. Mechanically isolated refrac wells with cemented tubulars inside existing well casing are exponentially more complicated to provide consistent holes due to perforating two strings of casing with cement in between. Fracturing is more difficult, resulting in fewer stages per day and increased costs. ReFRAC charges produce optimal and consistent holes to meet these challenges. Two major operators have seen two to three times the number of stages per day completed with fewer perforations. Costs and time on the well were reduced and profit margins increased. Multiple operators are requesting ReFRAC charge technology in this recompletion application.
Perforating system shortens gun length
The DynaEnergetics DS Trinity perforating system offers three charges in a single plane (three-in-a-plane) to shorten gun length and provide formation benefits during the hydraulic fracturing process. At less than 8 in. overall length, the new system is up to 3.5 times shorter than conventional perforating guns, enabling much higher gun counts per stage. Shorter gun lengths also save on running costs by reducing the height requirements for rigup cranes and pressure control equipment. The single-plane charge architecture has been determined to reduce formation breakdown pressure and achieve optimal rates quicker, which can ease wear and tear on fracturing equipment. In addition, single-plane perforating can lead to better fracture geometry in certain formations, enhancing overall well productivity. Recently completed field trials were conducted in partnership with a large U.S.-based independent operator that provided feedback on key features and functionality of the system. More than 1,000 guns were delivered during the field trial process, which was conducted with 100% success rate.
Technology eliminates clogged perforations
Kraken technology is a progressively burning, solid propellant designed to increase penetration, eliminate clogged perforations and overcome near-wellbore damage from compaction caused by traditional perforators. Progressively burning Kraken propellant boosters generate high-pressure gas in the perforation tunnels, which creates fractures that improve well connectivity. Completion engineers who scorecard breakdown pressure, IP/II increase, operating time and safety will observe that the return on incremental investment in enhanced perforating performance routinely exceeds 100%.
Interventionless perforating tool requires no electronic detonation
Nine Energy Service’s FlowGun technology is a stage one interventionless casing-conveyed perforating tool that eliminates the need to run wireline or coiled tubing (CT) and requires no electronic detonation. FlowGun offers an innovative, safe and cost-effective advantage for stage one completions. It offers infinite efficiency, control and flexibility. With FlowGun, operators see increased savings on time and money because the numerous downhole jobs are consolidated into one tool and one crew with no sleeves to shift, no wet shoe required and no electronic detonation needed. An entire phase of completion is eliminated, removing the need to pay for additional water, tank trucking BOP rental, CT, chemicals and labor.
Sliding sleeve tool helps operators avoid risks
While it is a very widely used completion method, plug and perf can have a negative effect on near-wellbore permeability, as the impact stress associated with the outward traveling shock of a shaped charge weakens the rock matrix and increases the risk of sand production. The i-Frac system from National Oilwell Varco (NOV) helps operators avoid the risks inherent in using conventional perforating methods with explosive charges and guns. The i-Frac is a hydraulically operating sliding sleeve tool that is threaded in as part of the production casing. Using a ball or a coil-conveyed tool, the sleeve is shifted, and perforations are exposed to the inner casing from inside; on the outside, perforations are covered up with cement. After this, a pressure increase breaks through the cement and initiates communication with the formation. A single stage can contain up to 20 i-Frac sleeves, with one ball dropped to activate all the sleeves and isolate the zone for stimulation treatment.
The i-Frac sleeves are ball-drop-activated multistage frac sleeves designed for cemented, multiple open/close and openhole horizontal completions.
Perforating gun system increases safety
Schlumberger’s Tempo instrumented docking perforating gun system is the industry’s first perforating gun system to fully integrate a plug-in gun with real-time advanced downhole measurements throughout the operation. This unique combination significantly mitigates operational risk while increasing safety, reliability and efficiency. By generating and confirming dynamic underbalance in the well, the Tempo system effectively removes perforation debris to optimize productivity. First-year deployments include North and South America, the Middle East, Europe and Asia. According to the company, excellent results have been achieved, from understanding the wellbore dynamics during perforation to achieving a 100% fires success rate on all guns deployed without any misfire. In Egypt an operator employed the Tempo system to improve the efficiency of multizone perforating operations in deep wells in the Western Desert. Conventional perforating gun systems had required significant operational time to assemble and arm, and their integrity could not always be verified until at perforating depth, at which point diagnosing any connection failures caused lengthy remedial downtime. The new plug-in gun simplified design saved considerable time, including reducing gun arming time by more than half.
The Tempo system 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.