Fit-for-Purpose Rotary Steerable System at Bit with Continuous Survey While Drilling Improves Challenging Drilling Operations and Well Placement

Abstract

Standard surveying technologies, including measurement while drilling (MWD) and rotary steerable systems (RSS), with multiple drilling bit choices, were initially used to drill 8-⅜-in curve and lateral sections with limited and varied results. In efforts to improve upon these inconsistent results, which negatively impacted well delivery performance, a new rotary steerable system at bit (RSSAB) and continuous survey while drilling (CSWD) tool were introduced to drill a combined vertical, curve and lateral section in one run to deliver a smooth wellbore with higher build rates in the curve, and faster overall drilling performance. This paper presents the continuous improvement seen from the onset of the first application of RSSAB and CSWD tool, which continues to the present day. Using specific digital-modeling, the RSSAB integrated both the steering and cutting structure to achieve a more optimum well trajectory while at the same time delivering better drilling performance. RSSAB was engineered with (1) pistons close to the cutting structure, (2) automated trajectory control with continuous six-axis inclination and azimuthal measurements, and (3) azimuthal gamma ray measurements close to the cutting structure. This new RSSAB eliminated the previous practice of reducing drilling parameters to achieve required build rates and to counter the turning tendency in the curve and lateral sections. This improvement enabled drilling with higher rates of penetration in the curve section, plus achieving higher dog-leg severity (DLS) in the curve, and also drilling a longer lateral section in one run with less tortuosity. CSWD was introduced to decrease surveying time and improve well placement accuracy. Excessive time was required when using conventional survey techniques, where surveys were taken every 95 ft during connection, and associated weight-to-weight connection time varied from 10 to 15 minutes per stand. This time was needed to free any trapped torque prior to taking survey, recycle pumps, and wait for survey to be transmitted and quality checked on surface. With new CSWD capability, time was eliminated as this function provides accurate 6-axis surveys continuously while drilling, thereby eliminating all related survey activity steps from operation. The increase in number of surveys obtained while drilling also enhances well placement and TVD definition for each well drilled. Introduction of fit-for-purpose RSSAB technology for the first time internationally outside U.S. land, and CSWD technology for the first time worldwide, has taken drilling performance to a new level, provided improvement in drilling performance, accuracy in well placement and associated cost reduction. In a short period of time, the drilling performance improved dramatically, and the top five wells with the vertical, curve and lateral sections drilled in one run had the highest average ROP. In addition, this newly deployed RSSAB and CSWD BHA achieved: The field record for the longest lateral footage drilled in one day.Fastest time from spud-to-TD.Fastest time from spud to rig release.

Study on Key Technologies of Geosteering for Shale Gas Horizontal Wells in the Complex Structural Area of Block H in Western Hubei-Eastern Chongqing

“…Such proactive adjustments ensure that the drilling trajectory remains optimally positioned within the reservoir. This provides foundational insights for subsequent trajectory refinements, significantly minimizing the risk of deviating from the target formation, especially in thin layers or small-scale structures. , The azimuthal GR can be used in real-time to determine the angle between the formation and the wellbore trajectory, and this calculation model can be represented using trigonometric relationships (Figure ). The adjacent side represents the amplitude of the sinusoidal curve aligned with the well tracjectory direction on the imaging, while the opposite side accounts for the wellbore diameter plus twice the tool’s investigation depth.…”

“…This provides foundational insights for subsequent trajectory refinements, significantly minimizing the risk of deviating from the target formation, especially in thin layers or smallscale structures. 28,30 The azimuthal GR can be used in realtime to determine the angle between the formation and the wellbore trajectory, and this calculation model can be represented using trigonometric relationships (Figure 10).…”

“…The azimuthal GR curve from near-bit or rotary steerable tools serves multiple purposes. Not only can it identify the lithology of the encountered formation and verify if the trajectory lands within the target formation, but it also accurately pinpoints the trajectory’s location within the target, its intersection pattern, and how it exits the target formation. ,− Specifically, the relative variations in the up GR (GR U ) and down GR (GR D ) values at a given measurement point can determine the relationship between the well inclination and the formation’s apparent dip angle and the bit’s relative position in the formation. For instance, when the formation’s GR shape displays a peak and GR U < GR D , the trajectory is ascending relative to the formation, indicating an upcut.…”