Sandeep Shashikant Janwadkar

Overcoming Drilling Challenges in the Marcellus Unconventional Shale Play Using a New Steerable Motor with Optimized Design

Although drilling horizontal wells in US-land unconventional shale plays has increased exponentially in the last few years, maximizing well productivity and improving drilling efficiency remains a major challenge. Well placement in the sweet spot and extended laterals help maximize productivity. Drilling a curve with higher dogleg severity (DLS) reduces its verticalsection and maximizes the length of subsequent lateral section in the productive zone. Wells in US shale plays demand a DLS of 10 to 14 deg/100 ft, but achieving high DLS presents numerous drilling challenges: rotating a steerable motor with a high adjustable kick-off sub (AKO) angle could result in bottomhole assembly (BHA) fatigue failure and premature damage to bit; drilling in oriented mode limits the transfer of weight to the bit, reducing the rate-of-penetration (ROP). These challenges led to the development and successful testing of a new steerable optimized design motor (ODM) with a short bit-to-bend (BTB) distance. In some cases, the ODM drilled all sections, including high-DLS curves, tangents and laterals with precise directional control and well placement with one BHA. Using the ODM helped the operator achieve higher build rates at lower AKO angle settings; rotate the BHA in well profiles where previously used motors could be operated only in slide mode, and maximize the length of curve interval drilled in rotary mode at higher rotations per minute (RPM). The new system significantly improved drilling performance with excellent directional control. Drilling high-DLS curves increased the length of laterals, enabling additional recovery of gas. This paper discusses the design, modeling and results of horizontal type wells drilled using the steerable ODM in the Marcellus unconventional shale play.

Real-Time High-Resolution LWD Images Used to Navigate a Carbonate Reservoir

The Permian basin of West Texas is one of the most mature and prolific oil provinces in the US, and continuously evolves in its production potential via the drilling of horizontal wells. A vital element to accelerate ROI is to accurately place the wellbore in the target formation. Determining and identifying the zone of interest within the carbonate interval and then navigating within it with conventional LWD technology has become a major challenge. To overcome these challenges, realtime high-resolution LWD images were proposed. Azimuthal gamma ray and multiple propagation resistivity measurements were used to determine bed dip, correlate position within the reservoir and indicate formation porosity variations. Advanced LWD imaging tools provide visual confirmation of steering up and down within the reservoir and identify structural information, porosity changes, rock type, faults and the location, density and type of fractures. This paper provides examples of reservoir navigation techniques along with the increased precision provided by imaging tools. Previously undetected faults, brecciated intervals, and fractures are identified. This enables a more precise completion design that reduces risk and increases production. Using this method, the percentage of the lateral interval in zone was increased to 100% from 77% in an offset well. Images of lateral variations in the formation will be presented. This information was used to optimize the completion design and is invaluable in the planning of future wells. LWD images are used to more efficiently drain the reservoir by providing the necessary information to stay in the target zone during longer intervals and assist completion optimization. LWD images can also be used to help explain production variances commonly observed between wells targeting the same interval.

High-Resolution LWD Images Used to Optimize Completions in Unconventional Play - North America

The Barnett Shale is one of the most mature and prolific natural gas fields in North America. It has a multi-trillion-cubic-feet equivalent upside potential but well completions are not resulting in consistent production within the same section or across the unconventional play. As infield drilling increases, collision and encroachment from well to well due from offset induced fractures, natural fractures, faults, and internal stresses are becoming more important to characterize and map. The operator and the service provider teamed up and used high-resolution images to optimize perforation placement, redesign stimulation, and stage placement. To overcome these challenges, high-resolution, state-of-the-art logging-while-drilling (LWD) imaging tools were used to acquire images on a well drilled between two 600-ft (182.9-m) offset wells. These images are also being used to map fracture systems, faults, and stresses in the field. With the knowledge obtained from these LWD images, completions are now being redesigned to incorporate this information for optimizing fracture treatments. The paper will provide examples of high-resolution images generated which were used to determine untreated formation matrix, and avoid faults for possible water production. Proper interpretations of these images and other advanced technologies have enabled operators to increase well productivity up to 20% as compared to offset wells. These advanced technologies have been implemented and used in over 250 wells with excellent results. The images will be used in the future to determine which wells would be the best candidates for recompletions. The lessons learned can be applied to most unconventional plays around the world.