Coiled tubing is utilized to enter horizontal wells for the purpose of performing general remedial well operations. Common operations performed include but are not limited to stimulation treatments, solvent treatments, cleanouts and water shut-off. In today's oilfield, many horizontal well plans incorporate the drilling of multiple laterals. Entering multiple laterals, in one well, using coiled tubing, requires guidance. Advanced completion designs may facilitate such guidance. However, in the case of open hole multi-lateral wells a guidance system is not incorporated in the completion design. This paper will discuss a reliable commercially available technology, developed for the purpose of entering open hole multilateral wells using coiled tubing. The paper will review bottom hole assembly functionality, development of this technology and applications. In addition, offshore case histories of wells entered using multi-lateral entry guidance technology will be summarized. Introduction Open hole, horizontal multilaterals exist in a number of fields throughout the world and have proved cost-effective to drill, delivering high rate wells in the short term. However, longer term, as the production declines and the water cut increases in the well, typical intervention operations are required: water conformance, stimulation, production logging and water shutoff to mention only a few. Open hole, horizontal multi-laterals are typically not designed for enabling interventions into the laterals during the lifecycle of the well. The usual method of intervention would require a drilling or workover rig to pull the completion and then use jointed pipe to guide the tools into the desired lateral, typically using a bent piece of pipe. However, the high rig rates, long workover times, limited rig availability, the inherent operational risks and the high potential for formation damage make workovers with a rig very costly. Alternatively, well interventions could be done through-tubing with coiled tubing, a much cheaper method of conveyance than jointed pipe. However, for coiled tubing to enter all the laterals in a open hole, horizontal multilateral well, a guidance system would be required as coiled tubing has no inherent steering capability. Presently today there is a reliable commercially available solution to enter multilateral wells using coiled tubing, the Lateral Entry Guidance System. Lateral Entry Guidance System: Solution to enter multilaterals Using Coiled Tubing The challenge of entering open hole multilateral wells is not a simple problem. Consideration was given to the problem with respect to how complex should the tool string be. Effective tool design should be "simple is best". For this reason, a tool was designed to ensure that laterals may be entered without electronic telemetry systems. Simple tools are easily introduced and implemented on a global basis thereby enabling access of this important technology to all operating regions. The lateral entry guidance system is a fluid activated tool. This enables the tool to be run on virtually any coiled tubing unit. In fact, the tool may also be run on jointed pipe if required.

It is common practice in the coiled tubing industry to manage the fatigue of straight wall coiled tubing (CT) strings by reversing the string on a work reel. The benefit is to shift the fatigue profile along the string by moving high fatigue sections away from high cycle depths in the well. This often helps extend the working life of the coiled tubing. For tapered CT strings, however, this is not a common practice. Tapered strings are traditionally not considered reversible as the effectiveness of the taper would be lost, and in some cases, pulling out of hole would exceed the yield strength of the tapered section of the string. In a large unconventional gas play, a tapered string was designed to be utilized for a number of completion activities on extended reach wells. String costs had a significant impact on the economics of the project. The strings were utilized until a given section exceeded 80% of the predicted fatigue life of the coil, and then in a conventional fashion, the strings were taken out of service. By evaluating the upcoming work on the project and the location of the fatigue spikes in the string the coiled tubing service company was able to develop a procedure to remove the fatigue spikes and manipulate sections of the string to gain additional useful life out of the string. Forward planning, special operating procedures and engineering analysis were used to gain over 60% longer working life of coiled tubing strings on this campaign.