Validation of Coiled-Tubing Penetration Predictions in Horizontal Wells

Abstract

Summary This paper compares the predictions of a coiled-tubing tubing-forces model (TFM) with actual measured data from more than 20 wells. The model predicts the maximum depth of penetration that the coiled tubing will be able to achieve before "helical lockup" is reached and predicts the weight indicator reading as the coiled tubing is pushed through the horizontal section to lockup. The predicted penetration depth and the weight indicator readings are compared with actual values recorded during the job for open- and cased-hole completions. Introduction Coiled tubing is being used increasingly to service highly deviated (including horizontal) wells as the number of these wells increases. Services typically performed with either electric line or slick line in horizontal wells are often performed with coiled tubing because the coiled tubing is rigid and can be pushed into the highly deviated section of the well. Services typically performed with drillpipe or conventional tubing often are performed with coiled tubing to avoid rig costs. The services currently being run in highly deviated wells include logging, perforating, setting and retrieving plugs, opening and closing sliding sleeves, fishing, removing fill, drilling, and matrix acidizing and acid washing. Several questions need to be answered when a coiled-tubing operation in a highly deviated well is designed. These questions include the following.How far can the coiled tubing safely penetrate and push tools into the deviated section?How can the operator ensure that the coiled tubing is being pushed into and not becoming bent in the well?How much weight can be applied with the coiled tubing to a drill bit or any other downhole tool at a point in the deviated section? To answer these questions, a TFM was developed specifically for coiled tubing. This paper describes this model, which has been validated with measured data from jobs performed in highly deviated wells.