In recent years, the number of horizontal wells drilled in the Permian basin of West Texas has increased. The Wolfcamp Shale is a prime target for horizontal well drilling because of its high liquids potential, which makes it an economically viable play. Ensuring maximum reservoir contact and successful hydraulic fracturing can be challenging in the Wolfcamp Shale, which is known for its highly heterogenous nature, high clay content, and high in situ stress.In the past, Clayton Williams Energy has had limited success stimulating its horizontal wells in the Wolfcamp Shale. These issues can be partially attributed to the highly stressed, laminated and heterogeneous nature of the formation. The conventional geometrically spaced perforation program that is typically selected when log data is not available or is not considered in the engineering design process can result in high pressure differentials between perforation clusters within a stage. The consequence of this includes reduced reservoir contact, incomplete proppant placement, screenouts, and skipped stages in parts of the lateral that are landed in higher stressed rock.In this study, openhole logging services acquired data through a specialized drill bit. These measurements were then integrated in an engineered staging and perforating workflow. The raw log data was processed to provide both petrophysical and geomechanical rock properties, which were used as inputs to quantify reservoir quality (RQ) and completion quality (CQ) for the engineered completion workflow. The workflow intelligently locates fracture stages and perforations by placing perforation clusters within a given stage in similar stressed rock as opposed to conventional geometric staging, which uniformly spaces out perforation clusters without accounting for the variability in rock properties along the lateral. The workflow honors the desired cluster spacing as much as the stress heterogeneity will allow. This optimization workflow was applied to a number of horizontal wells in the Wolfcamp formation of the Delaware basin in West Texas.The successful application of log measurements in the lateral for an engineered completion workflow resulted in the first stimulation treatment being placed 100% as designed with no issues. Three wells with log measurements where the engineered completion workflow was implemented showed, on average, a 67% increase in 90 days cumulative barrels of oil equivalent per lateral length compared to three geometric wells in the same area. A 28% increase in designed sand volume was pumped, and the operator also realized a 33% increase in successful stages, where more than 75% of the designed sand volume was pumped. The engineered completion workflow presented below describes a process that is meant to increase the effectiveness of stimulation treatments in horizontal well completions by increasing the percentage of perforation clusters that are stimulated and contributing to production.A 3D multiwell reservoir model was also designed using well log information from vertic...
Unconventional completions in North America have seen a paradigm shift in volumes of proppant pumped since 2014. There is a clear noticeable trend in both oil prices and proppant volumes – thanks to low product and service costs that accompanied the oil price crash in early 2015. As the industry continues to recover, operators are reevaluating completion designs to understand if these proppant volumes are beyond what is optimal. This paper analyzes trends in completion sizes and types across all major unconventional oil and gas plays in the US since 2011 and tracks their impact on well productivity. Completion and production data since 2011 from more than 70,000 horizontal wells in seven major basins (Gulf Coast, Permian, Appalachian, Anadarko, Haynesville, Williston and Denver Julesburg basins) and 11 major oil/gas producing formations were analyzed to examine developments in proppant and fluid volumes. Average concentration of proppant per gallon of fluid pumped was used to understand transitional trends in fracturing fluid types with time. Production performance indicators such as First month, Best 3 or Best 12 months of oil and gas production were mapped against completion volumes to evaluate if there are added economic advantages to pumping larger designs. In general, all major basins have seen progressive improvements in average well performance since 2011, with the Permian Basin showing the highest improvement, increasing from an average first-six-months oil production of 25,000 bbl in 2011 to 75,000 bbl in 2017. The Gulf Coast basin, where the Eagle Ford formation is located, has seen a 6-fold increase in proppant volumes pumped per foot of lateral since 2011 while the Permian and Appalachian basins hit peak proppant volumes in 2015 and 2016 respectively. In Permian and Eagleford wells, higher proppant volumes in general have resulted in better production up to a certain concentration. In Williston and Denver basins, most operators are moving away from gelled fluids, and reduced average proppant concentration per fluid volume pumped shows inclination toward hybrid or slickwater designs. While some of these observations are tied to reservoir quality, proppant volumes have begun to peak as operators have either reached an optimal point or are in the process of reducing volumes. Demand for proppant is expected to nearly double by 2020. As oil prices continue to recover, well AFEs continue to increase, despite multiple efforts to improve capital efficiency. The need for enhanced fracture conductivity and extended half-lengths on EURs are been discussed by combining actual observed production data and sensitivities using calibrated production models. The industry is moving toward large-volume slickwater fracturing operations using smaller proppants, but he operating landscape is expected to see a correction when such designs become less economical.
In the Permian basin, unconventional reservoirs have been the main target of horizontal well drilling since the early 2000s. Over the years, completion design in horizontal wells has evolved from conservative to radical designs. The main purpose of this paper is to evaluate different completion and stimulation design scenarios to understand their impact on hydraulic fracture geometry and production performance. This paper is an extension of a previous work presented by Ajisafe et al. at the 2016 SPE Hydraulic Fracturing Technology Conference (SPE-179130-MS) on the use of discrete fracture network from seismic data for complex fracture modeling. In most unconventional plays, the existence and interaction of the discrete fracture network (DFN) and hydraulic fractures during a stimulation treatment creates a complex fracture geometry. In the present study, seismic data provided an improved DFN model along and particularly away from the wellbore. The microseismic events showed variation in hydraulic fracture complexity and geometry along the lateral of the subject horizontal well. A multidisciplinary integrated workflow was applied to the horizontal well to model complex hydraulic fractures and production. The DFN model and geomechanical properties were key inputs into the unconventional fracture model (UFM) and were constrained with the microseismic data and production history. After the UFM model was created, different sensitivity categories such as proppant job size, cluster spacing, and maximum proppant concentration, were investigated for their impact on the complex fracture geometry as well as production performance. The field is an expensive laboratory. The use of advanced hydraulic fracture and reservoir simulation models can help provide the best completion design options from the start of field development as opposed to executing multiple field tests to determine the optimal design. The optimal completion design to increase hydrocarbon production with proper economics evaluation is critical for maximized returns. Single-well optimization is an important step in the unconventional workflow, and ultimately for better planning of multi well pad and infill well development.
The objective of this study is to understand the impact of key completion designs such as proppant and fluid volumes, cluster spacing, number of clusters, and fluid and proppant types on production in the Wolfcamp formation. Selected completion designs from the horizontal well study were used in a multi-well pad under different well spacing and stacking scenarios to understand the fracture geometry to minimize fracture interference and optimize production. Over the course of the study, which has been conducted since 2015, hydraulic fracture heat maps for the different completion designs were innovatively created to provide comparative analysis and directional insights for optimized well completion and well spacing designs in the multi-layered Wolfcamp formation. An integrated model was built with 3D seismic, petrophysical, geomechanical, core, and image log interpretation. The integrated model was used for complex fracture modeling and calibrated with microseismic data and production history match for multiple horizontal wellbores in the upper and middle Wolfcamp. Sensitivity analysis on various hydraulic fracture and completion designs were done to evaluate the fracture geometries, and the fracture footprint and its effect on production performance for both single and multi-well scenarios. Cluster spacing, number of clusters, fracturing fluid type, proppant types, proppant schedules, stimulation sequencing, etc. were some of the parameters evaluated in a well-scale modeling. High-tier completion designs were then translated into a multi-well pad under different well spacing and stacking scenarios for production optimization. Inter- and intra-well stress shadows honoring a realistic time sequence were also incorporated in the hydraulic fracture model. Fracture heat maps collapsing the complete wellbore hydraulic fracture geometries and their properties were created to represent the distribution of productive surface area for all the sensitivity cases. These heat maps were also compared to the observed microseismic data heat map for calibration purposes. Numerous fracture heat maps created from the sensitivity scenarios allowed evaluating the most effective completion design to optimize well completion, spacing, stacking and stimulation sequencing strategy. Proppant and fluid volumes as well as cluster spacing showed the highest impact on production performance in a single horizontal well. Increasing fluid and proppant volumes showed an increasing trend in the stimulated area. Decreasing cluster spacing showed an increasing trend in near-wellbore contact and fracture complexity. The number of clusters was shown to have minimal impact on production performance. Incorporating a stress shadow between wells representative of a zipper operation provides better coverage around the wellbore and allows for tighter well spacing. Heat maps created from microseismic data were in good agreement with the heat maps from the modeling of the different completion scenarios. Hydraulic fracture heat maps were found to be efficient and effective means to provide directional insights for decisions on holistic multi-well asset development. The workflow in this paper can be applied to single and multi-well pad developments in unconventional reservoirs. Understanding the impact of different completion and stimulation parameters on hydraulic fracture geometry and hydrocarbon production is crucial for proper optimization of resources. Hydraulic fracture modeling with production history match and diagnostic tests such as microseismic monitoring, tracers, production interference tests are highly beneficial in understanding key production drivers. The completion and hydraulic fracture heat maps also served as a visualization tool for providing comparative analysis of different completion scenarios. Incorporating economics in the workflow will provide the guidance needed to develop the unconventional reservoirs for maximized returns in the short and long term.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.