Randy C. Tolman

Advanced Multizone Stimulation Technology

ExxonMobil has developed two novel reservoir stimulation technologies that enable the rapid delivery of numerous highquality stimulation treatments within a single cased wellbore. These technologies were developed for the purpose of improving, or enabling, economic hydrocarbon recovery from formations that contain multiple stacked reservoir intervals or require the stimulation of long productive intervals. These technologies: (1) enable the stimulation of multiple target zones via a single deployment of downhole equipment; (2) enable selective placement of each stimulation treatment so that they may be designed specifically for each individual zone to maximize well productivity; (3) provide positive isolation between zones to ensure each zone is treated per design and previously treated zones are not inadvertently damaged; and (4) allow for treatments to be pumped at high flow rates to facilitate efficient and effective stimulation.

Just-In-Time Perforating for Controlled, Cost-Effective Stimulation and Production Uplift of Unconventional Reservoirs

Recent advances in multi-stage stimulation technologies, including open- and cased-hole types, have largely overlooked the advantages of single-zone stimulation due to hardware and cost limitations. In most conventional methods, multiple perf clusters are treated at once using one single frac stage with the expectation that equally-stimulated fractures will be created at each perf cluster within tens and hundreds of feet. This creates over-stimulation in some perf clusters and under-stimulation in others, which unveils the current economic and practical limits of effectively creating fractures where needed, not where it is possible to place them. Other methods use a large number of frac plugs which require additional wireline trips and later need to be drilled out, increasing the total cost and mechanical risk of the completion. As lateral length increases, many operators also face the challenge of not being able to remove all frac plugs due to coiled-tubing depth limitations. This paper introduces the recent implementation of Just-In-Time Perforating (JITP) in shale gas, unconventional plays. JITP is one of the Multi-Zone Stimulation Technologies (MZST) developed and patented by ExxonMobil over a decade ago and extensively used in vertical and S-shaped wells in the Piceance basin, Colorado, and recently implemented in the XTO Fayetteville Shale, Arkansas. JITP creates multiple single-zone fracture stimulations on a single wireline run using ball-sealer diversion and perforating guns that remain downhole during fracturing. Other key features of this method are the use of less horse power, significant reduction in the number of frac plugs, fewer wireline runs, and added flexibility in water management. This paper describes the technical advantages and business justification for applying JITP in unconventional resources and also provides preliminary results from the performance of the JITP field trials in horizontal wells.

Advancing Multi-Stage Fracturing Using Horizontal JITP and Autonomous Completion Systems

The execution and optimization of multi-stage fracturing treatments remains one of the most critical steps in the economic development of unconventional resources. Two recently developed and field tested technologies offer a step-change in fracturing operations: Horizontal Just-In-Time Perforating (JITP) and Autonomous Completion Systems. While JITP is a well-established technique (extensively used in the Piceance basin, Colorado), its application to horizontal wells is relatively new and promises improved single-zone stimulation, significantly less use of horsepower, reduced number of frac plugs, and added flexibility in water management. In addition, ExxonMobil is actively progressing its proprietary Autonomous Completion Systems that maximize surface equipment utilization by removing the need for umbilical intervention (wireline, coiled tubing, or tractors), which also eliminates the need for lubricators, lifting equipment, additional personnel and vehicles, and improves safety. This paper presents the latest milestones achieved in the development of these completion technologies. The application of JITP to horizontal wells was recently successfully confirmed with a comprehensive pilot program that included more than 30 wells and over 1400 single-zone treatments. Likewise, Autonomous Completion Systems entail broader applications beyond perforating systems. The key enabler for this technology is the frangible downhole navigation system which is undergoing field testing. In addition, the autonomous completion components are fully friable and do not require additional retrieval runs. The use of these technologies is anticipated to create new opportunities in equipment utilization efficiency and operational flexibility to the multi-stage fracturing methods available in the industry today.