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Production interference between parent and infill wells has become of utmost importance in unconventional reservoirs across the U.S. due to sub-par production performance of child wells as well as possible loss of production to the parent well. To mitigate production interference between parent and child wells, operators have applied various measures such as refracturing, repressurization of the parent well, and reducing child well stimulation jobs; these measures can be costly and yield mixed results. This study demonstrates the benefits of reservoir modeling to understand the effects of parent well production depletion on child wells at different well spacing as well as the use of successful mitigation strategies such as near-wellbore diverters and fracture geometry control to mitigate frac hits between wells drilled as close as 800 ft apart. A multidisciplinary integrated workflow was applied in a multiwell pad in the Bakken consisting of one parent and two child wells. The parent well was completed and produced for about 7 years, after which the two child wells were drilled 1,300 and 800 ft, respectively, on each side of the parent well. High-tier vertical logs were used to build a geomechanical and petrophysical model for the pad. The model was used for hydraulic fracture modeling and production history match of the parent well, after which the reservoir pressure depletion profile was used in a geomechanics simulator for an updated in situ stress state at 7 years. The updated stress state was then used for fracture modeling of the two child wells. The child well 800 ft from the parent well showed more hydraulic fractures directly hitting the parent well. The child well at 1,300 ft showed fewer hydraulic fractures directly hitting the parent well. The pressure depletion profile around the parent well had more negative impact on the child well at 800 ft away compared to the child well at 1,300 ft away because of its proximity. To eliminate this negative effect, fracture geometry control technology was used in the hydraulic fracture model for the child well 800 ft away from the parent well. It showed to be successful in reducing the occurence of frac hits to the parent well, diverting hydraulic fracture growth away from depleted regions around the parent well. During the actual operation, the results were confirmed with high-frequency pressure monitoring. Details of the field deployment of the fracture geometry control technology are discussed in detail in Vidma et al. (2019). No pressure communication was observed in stages pumped with the fracture geometry control technology. The child wells were completed and put on production without any sanding damage to the parent well, saving the operator approximately USD 400,000 and more than 2 weeks of deferred production if cleanout had been required. Actual production results showed superior performance in the child well at 1,300 ft away compared to the child well at 800 ft away. This confirms that the pressure depletion profile had more impact on the child well 800 ft away compared to the child well at 1,300 ft. Reservoir modeling is critical to understanding the level of pressure depletion in a producing well and its effect on child wells at different well spacing. It has also proven helpful in designing an optimum fracture geometry control pill to minimize the occurrence of frac hits that could damage parent well productivity.

Background: Graft right ventricular (RV) function is compromised directly posttransplant, especially in heart transplantation (HTx) recipients with pretransplant pulmonary hypertension (PH). Graft RV size and systolic function, and the effect of the recipient's pulmonary haemodynamics on the graft extracellular matrix are not well characterised in the patients long-term after HTx. Aim: Comparison of RV size and systolic function in HTx recipients' long-term posttransplant stratified by the presence of pretransplant PH. Methods: HTx survivors >/=2 years posttransplant were divided into group I without pretransplant PH (pulmonary vascular resistance, PVR /=2.5Wood units, n=16). RV size and systolic function were measured using cardiac magnetic resonance imaging (CMR). The collagen content was assessed in septal endomyocardial biopsies obtained at HTx and at study inclusion. Results: Mean posttransplant follow-up was 5.2+/-2.9 years (group I) and 4.9+/-2.2 years (group II) (p=0.70). PVR was 1.5+/-0.6 vs 4.1+/-1.7Wood units pretransplant (p/=0.07). Collagen content at transplantation and at follow-up were not different (p always >/=0.60). Conclusion: Posttransplant normalisation of pretransplant PH is associated with normal graft RV function long-term after HTx.

Successful United States shale plays are often used as a template for the drilling and completion strategies for newly emerging shale plays around the world. However, studies of production logs in the Barnett Shale, the Marcellus Shale, and the Eagle Ford Shale have shown that a significant percentage of perforations clusters are not producing quantifiable amounts of fluid or gas (Miller, 2011). Case studies designed to address this have shown that addressing the heterogeneity experienced near the wellbore (Wutherich, 2012) in combination with more focus on landing and staying in the best quality reservoir rock (Baihly, 2010) lead to more productive wells with a higher degree of perforation performance. Many operators face the challenge of incorporating a completion optimization workflow into their completions that is both technically and cost effective. The desired completion system is one that incorporates as much information as needed for successful completion while being operationally unobtrusive. Refined techniques used to convey dipole sonic tools in cased laterals have been supplemented by a new generation of easily deployed tools capable of making density, neutron, resistivity, and sonic measurements in open hole. This gives operators a wide array of options that can fit into a completion optimization program. This paper reviews the concept of optimized plug and perforation style completions as compared to the more frequently used approach of geometrically spacing stages and perforations. Reservoir quality and completion quality variables were used to design engineered completions in a multi-well study of Eagle Ford shale wells. The study used a cost effective work flow that is repeatable and portable in order to increase the effectiveness of hydraulic fracture treatments. The workflow is shown to improve overall production and well economics by increasing perforation efficiency.

Schlumberger and four Eagle Ford Shale Play operators drilling in South Texas joined a consortium initiative to acquire various types of open hole logging data in several horizontal wells, and use the data to design the completions with optimum fracture stage and perforation cluster positioning. Horizontal production logs were subsequently used to gauge the effectiveness of using the log data to engineer the completions. This paper outlines the data acquisition techniques, analyses made on that data, application, results and conclusion. Previous work carried out on production logging data acquired in several shale plays including the Eagle Ford (Miller et al, 2011) shows a significant variation in perforation cluster contribution. Other documented results showing the effect of targeting similarly stressed rock for fracture treatments (Waters, Heinze, Jackson, 2011) in the Marcellus. The objective of this study was to improve the initial flow capacity of the well by increasing the number of perforation clusters contributing to production. A related objective was to determine the optimal horizontal logging program that was needed to characterize the rock with minimal interruption to existing work flows. This paper will show the results of data acquired over 12 horizontal wells in the Eagle Ford Shale (see map in figure 1). Petrophysical and geomechanical analyses were based on horizontal logging measurements and used as inputs to an engineered completion design tool that generated a recommendation on each well design. The design tool grouped intervals with similar properties for stimulation treatment. Following the treatment, horizontal production logs were run through the zones to measure the perforation cluster contribution. The results of the study have the potential to change the way Unconventional Resources are developed. Recent trends have seen a shift away from data acquisition to blind geometrical fracturing. This paper examines the value of acquiring petrophysical data in the lateral section and its application to completion optimization, the minimization of wasted resources, and the impact on early production.

Summary Four operators drilling in the Eagle Ford Shale Play located in South Texas, USA joined Schlumberger in an initiative to acquire various types of open hole logging data in several horizontal wells, and then use the data to design the completions with optimum fracture stage and perforation cluster positioning. The wells were then evaluated with horizontal production logs to gauge the effectiveness of using the log data to engineer the completions. This paper will outline the processes used to acquire the data, the analyses made on that data, application, results and conclusion. The study draws on previous work showing perforation cluster contribution variation in several shale plays including the Eagle Ford (Miller, 2011), and other documented results showing the effect of targeting similarly stressed rock for fracture treatments (Waters, 2011). The main objective was to improve the initial flow capacity of the well by increasing the number of perforation clusters contributing to production. Another related objective was to determine the optimal horizontal logging program that was needed to characterize the rock with minimal interruption to existing work flows. This paper will show the results of data acquired over 12 horizontal wells in the Eagle Ford Shale. Petrophysical and geomechanical analyses were based on horizontal logging measurements and used as inputs to an engineered completion design tool that generated a recommendation on each well design. The design tool grouped intervals with similar properties for stimulation treatment. Following the treatment, horizontal production logs were run through the zones to measure the perforation cluster contribution. The results of the study have the potential to change the way Unconventional Resources are developed. Recent trends have seen a shift away from data acquisition to blind geometrical fracturing. This paper examines the value of acquiring petrophysical data in the lateral section and its application to completion optimization, the minimization of wasted resources, and the impact on early production.