As the petroleum industry ages, remediation of mature wells using cost-effective solutions is critical. Restoration of a well's production or mechanical integrity, or accomplishing water shut-off in wells whose production is on the decline, is commonplace the world over both on land and offshore. Mature environments, such as West and South Texas, provide an appropriate arena for refurbishing older wells that still have potential hydrocarbon production remaining.
Developing technology continues to address the challenges of well remediation while considering economic feasibility. One practical approach that is proving successful is a solid expandable tubular technology that consists of a new casedhole liner system. This liner system allows the customer todeploy more economical, standard oilfield tubulars and gas tight connections to make cased-hole repairs.
On one particular remediation, this new cased-hole liner system was used to cover 66 ft of perforations that could not be sealed successfully using conventional squeeze cementing methods. This liner system made it possible for the customer to fracture (frac) a lower zone with the high rates and pressures needed to carry out the frac job.
This paper will discuss the system design and testing of this innovative cased-hole liner system. The well preparation process, installation, and lessons learned from the application of the cased-hole liner technology will also be discussed. In conclusion, this paper will also include the liner system's potential impact on the restoration of older wells.
Solid expandable tubular technology has been in existence for over four years and to date over 120 jobs have been run in cased-hole and openhole applications under various downhole conditions. The solid tubular expansion process hydraulically and/or mechanically drives a solid mandrel through a specialized liner, coupled with proprietary expandable connectors. As the pipe expands, elastomer seal sections vulcanized on the outside of the expandable liner are compressed and energized against the base casing inside diameter (ID) forming a robust seal while generating the hanging capacity needed to serve as the liner hanger and the seal for hydraulic isolation. The resultant ID of the liner can be up to 20% greater than the original (Fig. 1).
While the solid expandable tubular operating envelope continues to evolve, many special applications demand a stepout from current capacities, and unique solutions are required. The original development of the flexible cladding system was prompted by just such a requirement. The operator needed a system which could provide a reliable, low risk alternative to cement squeezing perforations in an existing wellbore. The operator needed a system with the following specifications:
accommodate a 4-1/2 in. cased-hole application
withstand a high-temperature, high-pressure (HTHP) environment
provide a gastight seal across a perforated depleted zone
maintain minimal loss of pass-through ID
be cost effective
able to be delivered in three months