For coiled tubing stimulations each CT size offers various advantages and limitations, including but not limited to; maximum pump rate, logistics, fatigue life and cost. In extended reach (ERD) wells CT Tractors can be utilized to improve coiled tubing (CT) access of the horizontal section of the well-bore. The objective of this study was to compare the performance of a slim CT tractor with various sizes of CT, namely 2" and 2-3/8".
Tubing Force Analyses (TFA) were performed for a group of wells using CT modeling software with friction coefficients back modeled from previous CT interventions in the same field. Three similar candidate wells were chosen where CT was predicted to lockup prior to reaching Total Depth (TD) without the use of a tractor, and where TD was able to be reached with the use of a tractor for both 2" and 2-3/8" CT. During field operations down-hole pressure sensors and tension compression sub were included in the BHA to verify the effectiveness of the CT tractor with live readings.
The field operations demonstrated that 2-3/8" CT reached further in the wellbore prior to activating the tractor. The operations confirmed that the slim hydraulic CT Tractor was able to pull both 2" and 2-3/8" CT a significant distance past CT lockup depth. Matrix stimulations were successfully performed on each of the 3 wells. The study concludes that both 2" and 2-3/8" CT combined with a hydraulic slim tractor were both appropriate solutions to access extended reach open hole for Matrix stimulation operations.
Production engineers have case study results to show the effectiveness of using 2" vs 2-3/8" CT with a slim hydraulic tractor to access ERD wells for stimulation operations.