Optimized Steerable Motor Design Overcomes Drilling Challenges in Marcellus Shale Unconventional Play

Abstract

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 the bit; drilling in oriented mode limits the transfer of weight to the bit, reducing the rate-of-penetration.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 RPMs. 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 will discuss the design, modeling and results of horizontal type wells drilled using the steerable ODM in the Marcellus unconventional shale play.

Directional Steering Technique Development Trend of the Directional Drilling in the Oil and Gas Fields

“…수평시추기술은 대표적인 방향성시추의 한 방법으로 유전개발에 처음 도입된 것은 1929년 미국의 유전에서 였다 (Felczak et al, 2012). 그 이후 이 기술은 꾸준히 발 전되어 최근 북미지역 셰일•치밀가스 및 유전 개발의 활 성화에 견인차 역할을 담당하고 있다 (Jones et al, 2012). (Choi, 2011).…”