Well intervention in horizontal extended reach wells (ERWs) comes with a myriad of challenges and in the case of coiled tubing the overarching impediment is in reaching the target depth (TD). Frictional forces act against the coiled tubing (CT) while being pushed from surface, this eventually leads to helical buckling of the tubing and early lockup where no further progress is made. Advances have been made over the last decade with the development of high-tech downhole CT tractors that deliver a strong pulling force to overcome these frictional forces. Restrictions in the well completion require these tractors to collapse to 2-1/8″, and then to expand to the cased or open hole size of up to 6-1/8″. With many wells having a larger bore size of 8-1/2″, a CT tractor did not exist to improve the coverage in those type of wells. At first glance, modifying the existing tractor for 6-1/8″ sized holes to function in 8-1/2″ sized holes could be accomplished by simply extending the lengths of the arms. However, the reality is a little more nuanced with several innovations required to deliver the same pulling force as the 6-1/8″ tractor version. This new generation of downhole compact high expansion tractors have improved push-links and newly designed grippers to enable rig-less acid stimulation and production logging in ERWs. The high expansion tractor is an important facilitator in CT well interventions to tackle challenging ERWs by increasing the coverage in 8-1/2″ hole sizes. The CT tractor design, development, testing and first deployment was conducted in 2021. The major advantages gained from increasing the reach can be summarized as follows: The CT high expansion tractor enables successful reservoir surveillance and production monitoring, including improved reservoir understanding providing data to update and calibrate reservoir models.Acid stimulation in 8-1/2″ open hole wells on CT targeted fluid placement to improve well productivity to increase revenue per well.Detecting and then shutting off water inflow zones with CT techniques, avoiding the need for drilling a side track. This new generation of slim tractors is the first in the industry to operate in wells with a diameter of 8-1/2″ and an operating range from 8″ to 10″. The key metric to successful acid stimulation or logging applications in ERWs is the ability to achieve maximum coverage of the openhole section. These engineered solutions demonstrate how creative innovations in technology design are improving accessibility in ERWs, resulting in superior reservoir management outcomes.

Summary Successful reservoir surveillance and production monitoring is a key component for effectively managing any field production strategy. For production logging in openhole horizontal extended reach wells (ERWs), the challenges are formidable and extensive; logging these extreme lengths in a cased hole would be difficult enough but is considerably exaggerated in the openhole condition. A coiled-tubing (CT) logging run in open hole must also contend with increased frictional forces, high dogleg severity, a quicker onset of helical buckling, and early lockup. The challenge of effectively logging these ERWs is further complicated by constraints in the completion where electrical submersible pumps (ESPs) are installed, including a 2.4-in. bypass section. Although hydraulically powered CT tractors already existed, a slim CT tractor with real-time logging capabilities was not available in the market. In partnership with a specialist CT tractor manufacturer, a slim logging CT tractor was designed and built to meet the exceptional demands of pulling the CT to target depth (TD). The tractor is 100% hydraulically powered, with no electrical power, allowing for uninterrupted logging during tractoring. The tractor is powered by the differential pressure from the bore of the CT to the wellbore and is operated by a preset pump rate from surface. Developed to improve the low coverage in openhole ERW logging jobs, the tractor underwent extensive factory testing before being deployed to the field. The tractor was rigged up on location with the production logging tool and run in hole (RIH). Once the CT locked up, the tractor was activated and pulled the coil to cover more than 90% of the openhole section, delivering a pulling force of up to 3,200 lbf. Real-time production logging was conducted simultaneously with the tractor activation; flowing and shut-in passes were completed to successfully capture the zonal inflow profile. Real-time logging with the tractor is logistically efficient and allows instantaneous decision making to repeat passes for improved data quality. The new slim logging tractor (SLT) is the world’s slimmest and most compact and is the first CT tractor of its kind to enable production logging operations in openhole horizontal ERWs. The importance of the ability to successfully log these ERWs cannot be overstated; reservoir simulations and management decisions are only as good as the quality of data available. Some of the advantages of drilling ERWs, such as increased reservoir contact, reduced footprint, and fewer wells drilled, will be lost if sufficient reservoir surveillance cannot be achieved. To maximize the benefits of ERWs, creative solutions and innovative designs must be developed continually to push the boundaries further.