Field Trial Design and Analyses of Production Data from a Tight Gas Reservoir: Detailed Production Comparisons from the Pinedale Anticline

2011

All Days

Self Cite

Horizontal wells provide the opportunity to initiate multiple transverse fractures and dramatically increase the connection between the wellbore and the hydrocarbon-bearing reservoir. This has allowed the economic development of low permeability reservoirs that cannot be pursued without reservoir stimulation. Our success, however, does not imply that we are optimized. Recent field results in the Niobrara, Bakken, Viking, Haynesville, Eagle Ford and other reservoirs completed with transverse fractures are yielding answers to many questions, including: Are we achieving acceptable vertical height growth? What adjustments are necessary to accommodate multiphase flow? What fracture conductivity is needed? How many frac stages will provide the optimal economic returns? Are we effectively stimulating each stage? Are precautions necessary to avoid or reduce overflushing of proppant? Will restimulation of these reservoirs be necessary given current completion strategies? This paper explains the challenges of accommodating multiphase flow in transverse fractures and summarizes theoretical, laboratory, and field results demonstrating the best practices. Evidence is reviewed indicating that fractures fail to sustain hydraulic continuity through many laminations and techniques are suggested that can improve the ability to drain multiple stacked pay intervals with horizontal wells. Updated production results from the Bakken and Eagle Ford should be of benefit to any operator stimulating horizontal wells that produce significant oil, water, or condensate volumes.

Section: Effective Fracture Heightmentioning

confidence: 99%

Optimizing Transverse Fractures in Liquid-Rich Formations

2011

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“…There are numerous field examples in which ceramic proppant provided far superior production and total recovery of reserves than lower quality proppants [Vincent 2009]. Field studies in the Bakken [Besler 2007] and in the Pinedale [Huckabee 2005 andVincent 2007] have shown a low density ceramic to outperform a broadly sieved intermediate density ceramic (IDC) when utilized at depths of 10,000 to 12,000 ft TVD. This benefit is partially due to the 20% greater volume provided by a similar mass of a low density ceramic, and partially due to more uniform particle size.…”

Section: Proppant Selection and Restimulationmentioning

confidence: 99%

Improved Production and Profitability Achieved with Superior Completions in Horizontal Wells: A Bakken/Three Forks Case History

Rankin¹,

Thibodeau²,

et al. 2010

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The Bakken/Three Forks oil play is extremely active, with more than 2,500 horizontal wells drilled in Montana, North Dakota, and Saskatchewan during the past nine years. Typical well costs range between $4 -$8 million per well, suggesting the industry has invested more than $15 billion in this resource, in addition to lease, infrastructure, and operation expenses. Despite this enormous investment, the industry has struggled to identify best practices and many operators currently pursue significantly different strategies throughout the play. This paper will summarize the development philosophy and key learnings of one operator in completing this low permeability reservoir with hydraulically fractured horizontal wells. Significant production gains have been achieved through advancements in completion methods, improving the overall economics of the Bakken/Three Forks oil play. This paper describes the evolution of completion strategy, including: -Lateral length and number of stages -Method of isolation -Completion and fracturing techniques -Proppant type and concentrationThrough careful investigation and continual improvement, the authors have been able to significantly increase well production compared to their previous wells. Wells with improved completions have also experienced notably higher production rates than offset wells completed by operators with differing strategies. It is clear that lateral length and number of stages, coupled with proppant type and concentration, are key variables that have significantly improved well productivity and profitability. Included economic and financial analyses demonstrate that Bakken/Three Forks profitability can be dramatically improved by altering completion designs. Although specific treatment parameters should be adapted as formation characteristics vary across the play, it is believed this discussion of current design strategy will be useful to the SPE audience and accelerate optimization of Bakken/Three Forks completions. Future innovation will occur, and it is hoped that the publication of these learnings will encourage additional experimentation and optimization. This operator has drilled or participated in ~150 wells in the Bakken/Three Forks plays since 2006 and significant effort has been made to learn from experiences, design effective completions, and continuously optimize strategies to improve well performance. Excellent progress has been made, as early wells drilled by this operator produced merely 300 boepd on initial production, while recent completions have achieved over 5,000 boepd with close proximity and comparable reservoir quality. Finding and Development costs (F&D) have been reduced from ~$40 to ~$15 per barrel of recoverable reserves. With only a small percentage of locations drilled to date, this operator anticipates further improvement in completion strategies and corresponding production from future wells. Although Bakken drilling and completion practices will undoubtedly continue to evolve, it is believed that a discussion of this operator's e...

“…Although intuition often suggests that any fracture will provide infinite flow capacity compared to the formation, the immense surface area of propped fractures requires fluid to move hundreds of thousands, or even millions of times faster within the propped fractures than within the matrix (33) . Therefore, conductivity of proppant packs remains critical, both for cleanup of frac fluid and subsequent gas production (34,35) . More research and direct observations of proppant transport phenomena will hopefully shed more light on this important topic in the future.…”

Section: Conductivity and Proppant Transport In Light Sand Fracture Tmentioning

confidence: 99%

Stimulating Unconventional Reservoirs: Maximizing Network Growth While Optimizing Fracture Conductivity

Warpinski

Mayerhofer

Journal of Canadian Petroleum Technology

et al. 2009

320

Unconventional reservoirs such as gas shales and tight gas sands require technology-based solutions for optimum development. The successful exploitation of these reservoirs has relied on some combination of horizontal drilling, multi-stage completions, innovative fracturing and fracture mapping to engineer economic completions. However, the requirements for economic production all hinge on the matrix permeability of these reservoirs, supplemented by the conductivity that can be generated in hydraulic fractures and network fracture systems. Simulations demonstrate that ultra-low shale permeabilities require an interconnected fracture network of moderate conductivity with a relatively small spacing between fractures to obtain reasonable recovery factors. Microseismic mapping demonstrates that such networks are achievable and the subsequent production from these reservoirs supports both the modelling and the mapping. Tight gas sands, having orders of magnitude greater permeability than the gas shales, may be successfully depleted without inducing complex fracture networks, but other issues of damage and zonal coverage complicate recovery in these reservoirs. As with the shales, mapping has proved itself to be valuable in assessing the fracturing results. Introduction Unconventional reservoirs provide a significant fraction of gas production in North America and increasing amounts in some other regions of the world. Such reservoirs include tight gas sands, coalbed methane (CBM), and gas shales; in 2006 these reservoirs provided 43% of the US production of natural gas [Kuuskraa(1)]. Because of their limited permeability, which is foremost among many other complexities, some type of stimulation process (and/or dewatering in the case of CBM) is required to engender economic recovery from wells drilled into these formations. The focus of this paper is on gas shales, with particular emphasis on how these reservoirs perform relative to tight gas sands. The important role of natural fractures in both the stimulation and production processes, the importance of conductivity in the developed fracture or fracture system, and the critical influence of the matrix permeability are investigated using both mapping and modeling results.