Herringbone Drilling Technique: Innovatively Connecting Vertical Drains to Mother Holes to Maximize Drain Length, Cost Efficiency, and Production in Multi-Layered Reservoirs – A Regional First

Abstract Herringbone drilling, also known as herringbone multilateral horizontal well drilling, is a strategic approach in the oil and gas industry to enhance production efficiency and economic viability while mitigating environmental impacts. This paper aims to showcase the detail engineering planning and successful execution for first of its kind application of drilling herringbone wells in extremely long ERD drain hole in a multi-layered heterogenous reservoir in UAE. This method involves well design where multiple herring bone, which is +/-1000’ lateral branches connected with main bore sweeping reservoir vertically. This unique network of drain holes is planned by drilling lateral herring bone first then the well is sidetracked to drill main drain. The entire well is drilled in such a way that there is always accessibility in main drain hole to deploy lower completion consisting of ICD & Swell packers. This concept was first tested in an ERD well with one herringbone leg, then fully implemented in a multi-layered, heterogeneous reservoir. Four additional herringbone legs were added to the main wellbore, exposing five sublayers over 10,000 feet. This increased the drainage area, reduced the uncertainty ellipse area, making more area available to place drain hole, improved production by enhancing drain coverage, lowered construction costs, and minimized the environmental impact of drilling operations. This paper describes the feasibility of herringbone drilling in multi-layered heterogenous reservoir and the necessity of adopting advance drilling technology to maximize recovery and reduce well construction costs while mitigating environmental impacts.