Innovative Tool Improves Hole-Cleaning Efficiency in Extended-Reach Wells
Authors: Wilson Adam 
Published: January 2017

This article, written by Special Publications Editor Adam Wilson, contains highlights of paper SPE 175165, “Use of an Innovative Tool To Improve Hole-Cleaning Efficiency in Extended-Reach Wells in Saudi Arabia,” by Mike Okot, Marlio Campos, German Muñoz, and Alawi G. Alalsayednassir, Saudi Aramco; Matt Weber, Frank’s International; and Zahid Muneer, SPE, Schlumberger, prepared for the 2015 SPE Kuwait Oil and Gas Show and Conference, Mishref, Kuwait, 11–14 October. The paper has not been peer reviewed.

Saudi Aramco operates a large offshore oilfield development that has driven achievements in multilateral and extended-reach directional wells. One challenge the operator faces is to maintain proper hole cleaning in extended 8½-in. tangent sections at 85–87° inclinations, which are drilled in excess of 10,000 ft. In an effort to drill efficiently, a new technology to increase cuttings removal was trial tested on Well A1 from an onshore location of the field.

Introduction

Historically, drilling very long tangent sections required the use of several tandem sweep pills, wiper trips, and reaming and back reaming to maintain hole quality and remove cuttings from the wellbore efficiently. Poor hole cleaning can lead to tight intervals, increased torque and drag, and, eventually, stuck pipe.

Extended-reach Well A1 was drilled to a measured depth (MD) of 30,480 ft [8,650-ft true vertical depth (TVD)] into a stratigraphic environment composed of limestone, shale, and siltstone. The objective of the trial test for the tool was to improve the drilling efficiency. To obtain the best possible hole cleaning, a simulation was performed by placing the new tools every three stands along the tangent section in the 8½-in.-hole section.

The goals of the trial test were

To enhance hole cleaning by removal of cuttings

To reduce the frequency and number of tandem sweep pills

To reduce the frequency and number of wiper trips

To reduce torque and drag levels and make them comparable with those of offset wells

To reduce drilling cost

Well A1 resumed drilling from a preset 9?-in.-casing point in December 2013 in the Manifa field. The well was drilled from surface to 30,480-ft MD and into a stratigraphic environment composed of limestone, sandstone, and siltstone. The objective was to hold vertical from surface to 1,535 ft, build up to 85° from 1,535 to 11,659 ft, and hold an 85–90° inclination to total depth.

The challenges were to clean hole while drilling the long 8½-in. tangent section from 11,659 to 24,160 ft. To address these challenges, the tool company recommended the use of 5-in. cuttings-bed- impeller (CBI) tools at a frequency of one tool per three stands on the 5-in. drillpipe.

The 8½-in. tangent section was drilled smoothly without any hole-cleaning issues (no tight hole or stuck pipe). The primary hole cleaning was achieved during drilling, and no secondary hole cleaning was required.

A service company installed a cuttings-flowmeter system at the shakers to evaluate hole-cleaning efficiency and performance of the hole-cleaning tools.