Fracture nucleation and propagation are controlled by in-situ stresses, fracture treatment design, presence of existing fractures (natural or induced), and geological history. In addition, production driven depletion and offset completions may alter stresses and hence fracture growth. For unconventional oil and gas assets the complexity resulting from the interplay of fracture characteristics, pressure depletion, and stress distribution on well performance remains one of the foremost hurdles in their optimal development, impacting infill well and refracturing programs. To this end, ExxonMobil has undertaken a multi-disciplinary approach that integrates fracture characteristics, reservoir production, and evolution of the stress field to design and optimize developments of unconventional assets. In this approach, fracture modeling and advanced rate transient techniques are employed to constrain fracture geometry and depletion characteristics of existing wells. This knowledge is used in finite element geomechanical modeling (coupling stresses and fluid flow) to predict fracture orientation in nearby wells. In this paper, an integrated methodology is described using case studies for two shale gas pads. The study reveals a strong connection between reservoir depletion behavior and the spatial and temporal distribution of stresses. These models predict that principal stresses are influenced far beyond the drainage area of a horizontal well and hence play a critical role in fracture orientation and performance of neighboring wells. Strategies for manipulating stresses were evaluated to control fracture propagation by injecting, shutting-in, and producing offset wells. Collective interpretation of completion, reservoir depletion and changes in stresses explained varying performances of wells and enabled evaluation of infill potential on the pad. This workflow can be used to develop strategies for (1) optimal infill design, (2) controlling propagation of fractures in new neighboring wells, and (3) refracturing of existing wells.

Fracture nucleation and propagation are controlled by in-situ stresses, fracture treatment design, presence of existing fractures (natural or induced), and geological history. In addition, production-driven depletion and offset completions may alter stresses and hence the nature of fracture growth. For unconventional oil and gas assets the complexity resulting from the interplay of fracture characteristics, pressure depletion, and stress distribution on well performance remains one of the foremost hurdles in their optimal development, impacting infill well and refracturing programs. ExxonMobil has undertaken a multi-disciplinary approach that integrates fracture characteristics, reservoir production, and stress field evolution to design and optimize the development of unconventional assets. In this approach, fracture modeling and advanced rate transient techniques are employed to constrain fracture geometry and depletion characteristics of existing wells. This knowledge is used in finite element geomechanical modeling (coupling stresses and fluid flow) to predict fracture orientation in nearby wells. In this paper, an integrated methodology is described and applied to a shale gas pad as a case study. The work reveals a strong connection between reservoir depletion and the spatial and temporal distribution of stresses. These models predict that principal stresses are influenced far beyond the drainage area of a horizontal well and hence can play a critical role in fracture orientation and performance of neighboring wells. Strategies for manipulating stresses were evaluated to control fracture propagation by injecting, shutting-in, and producing offset wells. In addition, we present diagnostic data obtained from the pad that demonstrates inter-well connectivity and hydraulic communication within the pad. The workflow presented herein can be used to develop strategies for (1) optimal infill design, (2) controlling propagation of fractures in new neighboring wells, and (3) refracturing of existing wells.

In order to reduce stimulation costs, most conventional methods incorporate hydraulic fracturing of multiple perf clusters over multiple stages to treat large segments of shale rock in horizontally completed laterals. Under ideal situations, this technique would create equally-stimulated fractures at each perf cluster. However, in practice, such treatments can create overstimulation in some perf clusters and under-stimulation in others with unknown stimulated lengths and volumes. As operators move towards increased number of stages, increasingly larger number of plugs cause additional wireline trips and associated plug drilling time, which increases the total cost and mechanical risk of the completion. In some fields, operators use combinations of ball actuated sleeves and plug-and-perf methods due to technical limitations in drilling out of all the frac plugs. In response to these practical issues, ExxonMobil has implemented its proprietary Just-In-Time Perforating (JITP) technique in multiple horizontal wells over the last year. Prior to this deployment effort, JITP had been extensively used in vertical and S-shaped wells in the Piceance basin, Colorado. This paper discusses the learnings obtained after one year of multi-stage fracturing using horizontal JITP in unconventional plays. JITP creates multiple single-zone fracture stimulations on a single wireline run using ball-sealer diversion and perforating guns that remain downhole during fracturing. With the unique granularity of single-zone fracturing, much has been learned about the shale and treatment design. Better placement control can be useful in avoiding fracturing into offset wellbores. Field applications have confirmed the use of less horsepower, fewer frac plugs, improved fracture placement control, and added flexibility in water management. This paper also reviews technical considerations for other completion designs and fluid systems as well as opportunities for enhanced operations based on recent field learnings.