Williston Basin - A History of Continuous Performance Improvements Drilling Through the Bakken

Abstract

The Williston Basin has become one of the more lucrative oil reservoirs in North America over the past few years. The main reservoir occupies about 200,000 square miles of the subsurface of the Williston Basin, covering parts of Western North Dakota, Eastern Montana, and Southern Saskatchewan. The Bakken Formation was first discovered in 1951, but efforts to extract oil from it have historically been difficult. Efficient production of the Bakken has been achieved with long horizontal wells drilled through reservoirs at depths ranging from 8,000 ft to 10,500 ft (2,438 m to 3,200 m) true vertical depth (TVD). The target reservoir depths and the extended lateral wellbore lengths, require more powerful rigs to meet the operational demands of these well designs. The increased cost and tight economics associated with this play present a strong incentive to improve the drilling performance by reducing drilling time and cost. As a result, a strong focus was placed on improving drilling efficiency in the 9,000 ft to10,000 ft (2,743 m to 3,048 m) lateral wellbore sections, which have the largest impact on the overall well cost. This paper will introduce the challenges encountered when drilling these wellbore designs and outline the approach taken to optimize the drilling process. The usage of high-performance drilling motors, a review of previously used bottom hole assembly (BHA) concepts, and the benefits of gathering additional real-time downhole drilling data to validate or change best practices will all be discussed. The data presented has been gathered over the past 18 months, mainly in Dunn County of North Dakota, and will show rate of penetration (ROP) improvements of about 50% over this time period. This improvement in drilling efficiencies has proven to reduce the overall drilling time and has impacted the economics of this play significantly.

Energy Intensity and Greenhouse Gas Emissions from Tight Oil Production in the Bakken Formation

“…Bakken-specific values for drilling input parameters are derived from engineering literature. Drilling is assumed to be performed with a combination of top-drive and mud motor, with typical bit rotation speeds of 200–275 rpm. , The rate of penetration (ROP) is assumed in GHGfrack to be 110 ft/h (literature range is between 50 and 220 ft/h) in the vertical sections and 80 ft/h (range 40–120) in the horizontal segments. − Torque is lower in the vertical segment (9000 ft-lb, range 8000–10 000) than the horizontal segment (12 000 ft-lb, range 9000–13 000). ,− The mud motor is powered by high mud flow rates of hundreds of gallons (gal) per minute (vertical: 200 gal per min, range 150–400; horizontal: 500 gal per min, range 420–550) and a large pressure drop (vertical: 500 psi, range 450–550; horizontal: 700 psi, range 400–1200). , …”

“…31,33−35 The mud motor is powered by high mud flow rates of hundreds of gallons (gal) per minute (vertical: 200 gal per min, range 150−400; horizontal: 500 gal per min, range 420− 550) and a large pressure drop (vertical: 500 psi, range 450−550; horizontal: 700 psi, range 400−1200). 31,36 Hydraulic fracturing is modeled using GHGfrack, assuming that all fracturing fluid is injected at the mean Bakken fracturing gradient given the computed TVD for that well. The energy required to inject fracturing fluids in the Bakken is typically more than the energy requirement to drill a well.…”

Advancements and Operational Insights in the Bakken Shale: An Integrated Analysis of Drilling, Completion, and Artificial Lift Practices

“…This collection of research papers provides a detailed insight into the advancements in drilling technologies and efficiencies in the Bakken and Williston Basin Petroleum Systems, focusing on several key technical aspects: Djurisic et al [14] demonstrated a significant 50% increase in the Rate of Penetration (ROP) over 18 months, attributing this improvement to advancements in drilling technology and techniques, including the use of high-performance motors with pre-contoured stators and real-time downhole drilling data analysis. This enabled a more profound understanding of critical drilling parameters such as weight on bit and torque.…”

Study on Extended Reach Horizontal Well Multistage Fracturing Techniques for Tight Oil

“…Tight oil reservoirs have low porosity, low permeability, low production and high development costs, which requires a lot of horizontal well drilling and multi-stage fracturing to achieve commercial development value [1,3]. Generally, horizontal wells are applied in unconventional tight oil formation with horizontal length range from 1000m from 1500m [4,6].…”