Improving Well Productivity and Profitability in the Bakken—A Summary of Our Experiences Drilling, Stimulating, and Operating Horizontal Wells

Abstract

This case study will summarize the lessons learned during the stimulation and operation of horizontal laterals completed in the Middle Bakken formation of North Dakota and Montana. This paper will compare the production histories of these wells to offset wells completed with other techniques to evaluate best industry practices. Insight will be shared as to the effect of lateral length, wellbore azimuth and stimulation design on well production and overall well economics. The Bakken formation of the Williston Basin is undergoing significant development in Manitoba, Saskatchewan, Montana, and North Dakota. Numerous operators are active in the area, with a wide variety of development approaches. The industry has not yet reached consensus on optimal drilling and stimulation strategies. Results indicate significant progress in improving well production, while reducing the drilled lateral length and the treatment size. Efforts to improve diversion and optimize proppant type and size appear to provide more effective fracture treatments, while eliminating production problems related to the flowback of frac sand. This paper will provide the following benefits to readers:Operators in the Bakken have experienced significant problems with flowback of frac sand, requiring frequent pump changes, conservative production strategies, and expensive cleanouts prior to restimulation. This paper will describe the steps taken to eliminate proppant flowback into the wellbore and the estimated economic impact.This paper will provide a case study comparing the production from wells completed with a variety of strategies.The results suggest many current laterals drilled in the Bakken are ineffectively stimulated and demonstrate that significant increases in well profitability are possible with more optimized treatments.Optimizing fracture treatment designs for horizontal wells requires an estimation of the fracture geometry - particularly a description of the intersection between the wellbore and the fracture. A fracture treatment designed under the assumption of a longitudinal frac will be entirely inadequate if the actual fracture propagates in a transverse orientation. This paper will describe our understanding of the fracture geometry and how that has affected treatment designs. Introduction The Middle Bakken play of the Williston Basin has generated significant interest, with over 45 companies completing wells in North Dakota and Montana and additional development activity accelerating in Canada (Figure 1).

Multidimensional, experimental and modeling evaluation of permeability evolution, the Caney Shale Field Lab, OK, USA

“…However, it should be noted that the use of proppants that increase the fracture conductivity such as ceramic coated proppants are more likely to generate higher performance in the long term but are very expensive and unfeasible in field development. Besler et al (2007) observed that long-term production was sustained from wells where ceramic proppants were used as compared to conventional sand implying that the type of proppants used can significantly affect production.…”

The Application and Misapplication of 100-Mesh Sand in Multi-Fractured Horizontal Wells in Low-Permeability Reservoirs

“…The practice of overflushing or overdisplacing fracture stimulation treatments, to maintain a clean wellbore for plug-and-gun pump-down operations, has raised concerns by some in the industry (Vincent and Besler, 2013, Besler et al, 2007, van Gijtenbeek, Shaol, and de Pater, 2012. A common observation on wells where production logs or oil-based tracers are used to compare production contribution from individual stages is that the stage closest to the heel of the well often is the most productive, such as one well in a study by Goswick and LaRue (2014).…”

Stimulating Unconventional Reservoirs: Maximizing Network Growth While Optimizing Fracture Conductivity

“…With cross-linked fluids in the Bakken formation, 20/40 sand has been pumped to surface in offset wells 2,200 feet away from the treatment wells (26) . With slickwater fluids, Leonard et al (27) have reported tracer surveys indicating radioactive traced sand being identified in offset wells at distances of 500 feet with 40/70 mesh sand.…”

“…This approach may not always apply in horizontal wells, as it does not consider the intersection between the wellbore and fracture and the associated flow convergence. Dedurin et al (33) and Besler et al (26) have demonstrated that transverse fractures have entirely different conductivity requirements compared to longitudinal fractures.…”