DeepReach Coiled Tubing Service
Extends Reach up to 30% Compared to Conventional Tapered CT String
DeepReach™coiled tubing uses multiple outer diameter coiled tubing sections in a single string with larger OD sections near the top of the string and smaller OD sections near the bottom. With this arrangement, the tension along the string length is reduced while suﬃcient ﬂow capacity is retained for performing well intervention operations.
Tapered OD Makes the Difference
The vertical depth capability of conventional coiled tubing is limited because as the length of the tubing string increases in the well, the string’s total weight also increases; therefore, the capability of a conventional CT string to perform ultra-deep work depends primarily on the string’s total hanging weight and the yield strength of the parent metal. If the hanging weight exceeds the pipe’s yield strength, a string separation can occur. Since a tapered coiled tubing string is lighter in weight (compared to a single string of the largest diameter) and its design provides greater strength at the upper end of string, operators can realize up to a 30 percent increase in depth capability over conventional CT strings.
Key Enabling Technologies
Multiple technologies were developed to enable DeepReach coiled tubing to be used in deep well operations. These technologies include 1) the CT transition joints, 2) Boots & Coots V-Block® gripper design, 3) special injector head modiﬁcations to our patented twin carriage design, 4) variable diameter well control equipment and 5) adaptation of the simulation program to model and design operations using tapered OD coil tubing. Each of these technologies is critical to the successful deployment of a tapered CT string.
Coiled Tubing Transition Joints
The precision transition joints are key components of the DeepReach system and are designed for each coiled tubing size. Each end has a section of conventionally conﬁgured tubing with a transition section in the middle. The transition section is engineered and manufactured to minimize stress risers. The shape and length of the joints vary for diﬀerent tubing sizes.
Coiled Tubing Injector with V-Block® Gripper
Boots & Coots DeepReach service utilizes ﬁeld-proven twin carriage coiled tubing injectors with V-Block gripper blocks to enable handling full weight and speed capacities through the changing ODs and transition joints. These injectors are available with maximum pull capacities up to 135,000 lb and have been used for deepwater well intervention services in the Gulf of Mexico.
The two most critical points during the injection of a tapered CT string are when the most nonuniform loading occurs which is a)where the taper starting point is at the beam midpoint and b)where the taper end point is at the beam midpoint. Special modiﬁcations maintain a suﬃciently uniform beam pressure as the transition joint passes.
Boots & Coots V-Block gripper blocks help enable this technology by negating the requirement to change blocks when changing tubing diameters between jobs.
Pressure Control Stack for DeepReachSM Service
To meet a variety of design standards to seal at 15,000 psi on all sections of the tapered coiled tubing, the stack required variable bore components that not only function over the range of straight OD tubing within the string, but also over the tapered transition joint. The DeepReach service pressure control stack includes variable OD pipe rams, slip rams, and stripper. The variable OD rams eliminate the necessity for adding additional BOP cavities to accommodate the various diameters of the string, enabling the use of existing BOP equipment bodies with only internal component changes.
The DeepReach system has been thoroughly ﬁeld tested for both durability and ﬂow characteristics. System development was a joint project with BP. Quality Tubing, Texas Oil Tools and CTES also were involved in the development team, each playing a critical role in their respective component development.