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Abstract The emerging Vaca Muerta Formation, located in the Neuquén Basin in Southern Argentina, is the most successful Unconventional Play outside the United States. The development of this Formation has started several years after the massive development of US Shale Plays, giving local operators the opportunity to incorporate lessons learned and best practices applied in other Basins. Completion Designs are considered to play a key role to maximize the ultimate recovery in unconventional reservoirs. Fortunately, classic hydraulic fractures designs, legacy from conventional reservoirs, have rapidly evolved to modern designs, more suitable for unconventional reservoirs. From vertical wells with hybrid completion fluids to multi-fractured horizontal wells including High Density Completion (HDC) techniques, Engineering Completions (EC) and Variable Shot Clusters (VSC), US Shale experience has accelerated the learning curve in Vaca Muerta Formation. Design of Experiments (DoE) was used to leverage numerical models' capabilities and optimize hydraulic fractures designs. This contribution summarizes state-of-the-art completion techniques successfully applied in Vaca Muerta Formation. Introduction Pan American Energy is leading the State-of-the-Art completion techniques executed in Vaca Muerta Formation using straightforward processes to make decisions and rapidly adopt lessons learned and best practices from US Shale Plays. The subsurface team has played a key role leading the continuous improvement of completion designs. The stimulation team has applied operational excellence execution to make the improvements happen. A multi-disciplinary team between reservoir engineers, geomechanics and stimulation engineers is mandatory to successfully apply the Deming Cycle (Plan-Do-Check-Act) to hydraulic fractures designs. It is important to mention, that not all techniques that were successfully applied in US Shale Plays are expected to be successful in Vaca Muerta Formation, from different rock properties to limited technology availability (i.e., oriented perforations, variable perforations diameter, etc.), the completion optimization process in this Formation is a unique challenge. Completion Design Evolution in Vaca Muerta Since the first horizontal well drilled in Vaca Muerta (2011), hydraulic fracture designs have evolved significantly. More Proppant and Fluid Intensity was pumped in the most recent wells and reduced stage spacing were executed to evenly distribute the treatment along the well. Additionally, the standard deviation around design parameters increased from early 2019 as part of the optimization process that operators are looking for (Figure 1).
- South America > Argentina > Patagonia Region (1.00)
- South America > Argentina > Neuquén Province > Neuquén (1.00)
- Geology > Geological Subdiscipline > Geomechanics (1.00)
- Geology > Petroleum Play Type > Unconventional Play > Shale Play (0.65)
Abstract Multiple transverse fractures initiated in a horizontal wellbore are the most effective method to maximize formation contact and access reserves in unconventional reservoirs. Most horizontal well operations in unconventional reservoirs utilize multi-stage/multi-cluster plug and perforation completions. Optimization of unconventional resources requires improvements in the number of effective clusters within the designed stage length and sizing fracture treatments that are appropriate for the lateral and vertical spacing between wellbores. However, it can be challenging for operators to routinely and inexpensively 1) evaluate cluster performance within each stage, 2) analyze fracture propagation and complexity pressures and 3) determine fracture geometry resulting from the treatment design. Fracture treatment stage data is under-utilized and provides an opportunity for completion and stimulation optimization. This work focuses on a novel methodology to assess tubular and near well perforation pressure loss and limited entry success, determine cluster effectiveness, evaluate diverter performance, analyze fracturing pressures, and provide as-placed fracture geometry using stage treatment data. No changes to routine fracturing operations are required and stepdown tests are not necessary. After evaluating these key performance indicators, future completions can be optimized to achieve specific objectives including 1) improved cluster efficiency, 2) efficient fluid and mass placement per cluster, 3) stress and fracture shadowing component pressure management and 4) achieving fit-for-purpose created and propped fracture half-lengths. This work has been applied to multiple unconventional basins in North America. The methodology honors first-order principles and has been calibrated with multiple diagnostic technologies including optic-fiber, stepdown testing, RA and CFT tracing, fracture modeling and production data analysis methods. Results will illustrate varying stimulation and completion design variables, including the effects of perforation size and number, cluster spacing, application of diverters and mechanical stress shadowing. The effects of cluster performance on fracture length will be shown. The methodology is useful for stand alone, single well applications, however, increased value is gained with multiple well and multiple pad assessments. Using readily available hydraulic fracturing treatment data, completion and reservoir engineers and geoscience teams obtain meaningful results accelerating the learning curve and are provided a large parametric population for multivariant analysis and machine learning applications. The methodology presented provides a low-cost, scalable diagnostic solution for each completion stage within the horizontal well. Application of this methodology provides the fracture design engineer with new tools to optimize well performance using existing data.
- North America > United States > Texas (1.00)
- North America > United States > Colorado (1.00)
- North America > Canada (0.93)
- (3 more...)
- Geology > Geological Subdiscipline > Geomechanics (1.00)
- Geology > Petroleum Play Type > Unconventional Play > Shale Play > Shale Gas Play (0.46)
- North America > United States > West Virginia > Appalachian Basin > Utica Shale Formation (0.99)
- North America > United States > West Virginia > Appalachian Basin > Marcellus Shale Formation (0.99)
- North America > United States > Virginia > Appalachian Basin > Marcellus Shale Formation (0.99)
- (46 more...)
Abstract Through near 3000 horizontal producing wells on University Lands in the Permian Basin, we have performed a series of case studies to systematically investigate the most critical parameters to maximize well performance and the value of field development. In addition to summarizing multiple study results, the paper concludes and elaborates that the effective cluster spacing is the most critical parameter that we may be able to control and can influence the most in the unconventional reservoir development. The paper first shows three observation cases of perforation cluster spacings and their corresponding well performance. To understand why the effective cluster spacing is so vital to well performance, we then illustrate the fundamental theory to understand the pressure propagation timing and depletion patterns in different reservoirs. We compare the mechanistic modeling results of pressure depletion and corresponding recovery efficiencies with different effective cluster spacings by multiple modeling approaches, including single-porosity model, and dual-porosity model, which has validated our case study results and is very insightful for us to optimize perforation cluster spacings. We then discuss the possible reasons of often-observed well interference. With a large data sample, the paper illustrates the good correlation between well performance and completion effectiveness. The paper presents the EUR and NPV evaluation results of different field development case histories, such as between tight cluster spacing and wide cluster spacing. We will also briefly discuss the current technologies and practices to improve cluster efficiency in the completion process. Based upon the multiple case studies, theory investigation, and rigorous modeling, we have concluded that the effective cluster spacing is the most critical factor to influence well performance and the field development value. The workflow illustrated in the paper can be used for operators to systematically optimize their cluster spacings as well as field development plans. To maximize the value of developing unconventional reservoirs, it is vital to optimize cluster spacing and cost-effectively achieve tighter effective cluster spacing.
- North America > United States > Texas (1.00)
- North America > United States > New Mexico (1.00)
Practical Design Considerations for Stage Length, Perforation Clusters and Limited Entry Pressure Intensities
Huckabee, Paul (Shell Exploration & Production Co.) | Ledet, Chris (Shell Exploration & Production Co.) | Ugueto, Gustavo (Shell Exploration & Production Co.) | Tolle, John (Shell Exploration & Production Co.) | Mondal, Somnath (Shell Exploration & Production Co.)
Abstract This paper presents design considerations and field trial applications for determining practical dimensions and limits for interdependencies associated with stage length, perforation clusters and limited entry pressures. Recent applications by multiple authors and companies have begun to reverse the decade-long trend of reducing stage length and perforation spacing, in favor of extending stage lengths, to capture free cash flow value for unconventional resource development. Aggressive limited entry has been an enabler for successful extended stage length applications. Multiple authors have advocated "eXtreme Limited Entry" (XLE) applications. We present diagnostics data and applications that challenges the need for XLE and better constrains the necessary amount of limited entry pressures for effective stimulation distribution for resource development across multiple North American Basins. Data is presented from integrated application of field trials, stimulation distribution diagnostics, and well performance analysis. Field trials and well performance analysis are from the Permian Delaware Basin Wolfcamp. The field trials include both: greater perforation cluster intensities for base design stage lengths; and extended stage lengths of 50% greater than the base designs. Diagnostics are from multiple North American Basins and include discrete treatment pressure diagnostics and optic fiber distributed sensing. Data is presented to quantify the magnitude and variability for components necessary for maintaining active fracture extension for multiple perforation clusters. Components include: fracture breakdown pressures; in-situ stress, net fracture extension pressure, and near wellbore complexity pressure drop. Data and examples are presented from multiple wells, and resource development areas, to show the variability in measured treatment pressures for different length scale dimensions. This variability is used to determine the amount of limited entry pressure required to maintain fracture extension, dependent on the stage length dimension. Although Aggressive Limited Entry (ALE) is generally required to enable effective stimulation distribution and extended stage lengths in multiple cluster stages, examples are presented that demonstrate XLE is generally not required. We also discuss some of the considerations and observations that limit perforation cluster spacing intensities. Well performance data from the field trials is presented to validate the applications. This work demonstrates the value of integrated application of field trials, stimulation distribution diagnostics, and well performance analysis to capture free cash flow value from improved completions and stimulation designs. The discussion will include an assessment of future opportunities for further extension of stage length dimensions.
- North America > United States > Texas (0.68)
- North America > United States > New Mexico (0.50)
Abstract To economically and efficiently develop unconventional resource plays, the industry has been spending tremendous resources to optimize completion and well spacing by piloting – a trial-and-error approach. However, the approach tends to take long time and cost significant amount of money. As the complex fracturing modeling technology advances, we question: "Can we use the latest complex fracturing modeling and reservoir simulation technologies to optimize completion and well spacing?", so that the industry can significantly save piloting time and money, and quickly find the optimal well spacing and corresponding optimal completion. A recent case study in Permian Basin has answered the question well. For a Wolfcamp well completed with crosslinked gel and wide cluster spacing in 2012, we first built a 3-D geological and geomechanical model, and a full wellbore fracturing propagation model, and then calibrated it with multi-stage fracturing pumping history; the resulting complicated fracture network model was then converted into an unstructured grid-based reservoir simulation model, which was then calibrated with the well production history. During the process, discrete natural fracture network (DFN) and stress anisotropy were systematically evaluated to study their impact on fracture growth. Microseismic and tracer log data were used to validate the hydraulic fracturing modeling results. To test if the calibrated geomechanical and reservoir models can be used to optimize well completion design, we then ran the fracturing model with the latest completion design (tighter cluster spacing, slick-water, and more fluid and proppant) and forecasted the well performance. We found out that the resulting well performance is very similar to the performance of those wells with similar completion designs in the same area. After establishing the confidence on the capacity of those models, we then further studied the impact of different completion designs on fracture dimensions and well performance. We examined the distributions of fracture length along the wellbore resulted from different cluster spacings, fracturing fluid types and volume, and proppant amount. We found out (1) the hydraulic fracture length and network complexity mainly depend on DFN and stress anisotropy, and fracturing fluid viscosity; and (2) the fracture length of those fractures initiated from different perforation clusters along wellbore is in a log-normal distribution depending on completion designs, which provides crucial insights to well interference and furthermore on well spacing. Therefore, we can reasonably model complicated fracture propagation and corresponding well performance with the latest modeling technologies, and then optimize well spacing, which should help operators save significant time and money on well completion and spacing piloting projects, and thus speed up field development decision. The paper demonstrates our novel workflow as an effective way to optimize completion design and well spacing by integrating advanced multi-stage fracture modeling with reservoir simulation in unconventional resource plays.
- North America > United States > Wyoming > Laramie Basin > Niobrara Formation (0.99)
- North America > United States > Texas > Permian Basin > Yeso Formation (0.99)
- North America > United States > Texas > Permian Basin > Yates Formation (0.99)
- (31 more...)