Securing Long-Term Well Productivity of Horizontal Wells Through Optimization of Postfracturing Operations

Abstract

Poststimulation operations on multistage hydraulically stimulated horizontal wells producing from conventional and unconventional reservoirs have a major impact on long-term well performance. Most common types of poststimulation services on such wells include plug drillout (PDO) operations and well flowback (WFB) operations. During these operations, the hydraulic fracture system experiences major changes in pressure and flowrate, which may affect the well's long-term productivity. Among the many mechanisms responsible for decrease in well productivity, we highlight 1) the risk of losing the connection between the wellbore and hydraulic fracture system because of the development of an unpropped area; 2) rock destabilization, and 3) the risk of scaling and precipitation. In this paper, we describe an integrated engineering and operations workflow for optimizing poststimulation operations on horizontal wells by controlling the productive fracture system evolution during the poststimulation period. The approach is based on applying the secure operating envelope (SOE) concept, which provides a set of operating parameters that ensure preservation of the connection between the hydraulic fractures and wellbore. The SOE is defined for each individual well, using a combination of geomechanical and multiphase transport modeling. It accounts for reservoir properties, well completion, and fracture treatment parameters. High-resolution, real-time monitoring of well performance and active control of bottomhole conditions through choke management ensure the well is operated within the SOE. The production objectives combined with the evolution of the SOE enable an overall strategy for poststimulation operations. The paper outlines how the SOE is constructed. Applications of the proposed approach on horizontal oil and gas wells in unconventional reservoirs in North America are reported, both during well flowback and plug drillout operations. Using the SOE during well flowback helps to predict and avoid a decrease in well production performance caused by excessive proppant flowback which results in creation of near-wellbore pinch points inside hydraulic fractures. Additionally, plug drillout was identified as a critical operation, during which the proppant pack can be destabilized. The associated risk was strongly reduced by applying the SOE concept in combination with high-resolution monitoring. Based on data obtained from more than 50 operated wells, we conclude that the proposed methodology, including application of geomechanical modeling to poststimulation operations, brings significant opportunities for optimization of well performance and securing long-term well productivity.

A Literature Review of CO2, Natural Gas, and Water-Based Fluids for Enhanced Oil Recovery in Unconventional Reservoirs

“…This review will not delve into efforts toward enhanced gas recovery from unconventional gas reservoirs that produce little, if any, oil, − such as the fields in the Barnett, the Qusaiba in Saudi Arabia, and the Longmaxi in China. ,− Mechanical approaches to improving oil recovery such as improving the fracturing process, − optimizing wellbore geometry or spacing and stability, , improving perforation strategies, controlling proppant placement, modeling fracture patterns, developing choke management strategies, improving postfracturing operations and fluid cleanup, , refracturing, , production data analysis, and improving well monitoring technology, are also beyond the scope of this review.…”

A Data-Driven Workflow Approach to Optimization of Fracture Spacing in Multi-Fractured Shale Oil Wells

“…Although Equation 3shows that maximum well productivity can be obtained by optimizing the effects of the number of hydraulic fractures, hydraulic fracture spacing, and hydraulic fracture width, this is not true in reality as fracture complexity and additional factors such as frac hits also exist. As pointed out by Potapenko et al [17], in most of the unconventional reservoirs where the majority of multistage wells are drilled, the fracture geometry is quite complex and interaction between fractures starts very early. In this case, spacing between perforation clusters should not have much impact on well productivity.…”

“…In this case, spacing between perforation clusters should not have much impact on well productivity. However, in situations where a significant portion of hydraulic fractures is damaged during well startup, resulting in disconnections of such fractures from the wellbore, having small spacing between perforation clusters still appears to be beneficial because disconnected fractures still may contribute to production through other nondamaged perforation clusters [17]. The issues of fracture complexity, interaction, and disconnection are quite difficult to consider in mathematical modeling because there is a lack of data to explicitly describe their configurations and dynamics [18].…”

A Comprehensive Review of Fishbone Well Applications in Conventional and Renewable Energy Systems in the Path towards Net Zero

“…Although this combination has been successful in providing access to previously inaccessible resources such as shale formations [41], they still suffer from some challenges. Multi-stage hydraulic fracturing in low permeability formations could suffer from rapid well productivity decrease due to fracture closure, lack of knowledge about fracture propagation, and proppant displacement issues [42][43][44]. Also, fracture initiation remains a concern, leading to fracture tortuosity, screen-outs, and uncontrollable fluid distribution between stages [45].…”