Economics is a universal driving force in the oil and gas industry whether offshore or on land, and the "all or nothing" gas market of the Netherlands is no exception. With extremely heavy demand in the winter and very low demands in the summer, the capacity to cover the peak demands pays very high returns.

The capability to boost significantly the production capacity of existing wells by increasing the size of the completion is both economically and environmentally attractive. The development of a 13% chromium (13Cr) solid expandable tubular production quality liner enables the operator to gain extra capacity without drilling infill wells or building more surface facilities. Furthermore, abandonment costs are not affected.

Solid expandable tubular technology also provides operators with the flexibility to respond to the sudden increase in future gas demands as dictated by the market. Development of new sealing systems, expansion assemblies, and gas tight expandable connections were required to make this technology a reality.

This paper discusses the planning, testing, and application of this environmentally sound and economically advantageous technology. In this particular application, productivity of the well increased from 38.5 mln scf/d to 63.5 mln scf/d. The paper also expounds on the potential impact this technology will have on the future of the oil and gas industry.

Reviewing Energy Requirements

A 1999 annual review of the Groningen field in the Netherlands revealed that capacity requirements could exceed the installed capacity of the field by 2006. This production differential, in addition to cyclical customer needs, led the producer to search for a means to increase production and still remain within economic parameters.

Two major well engineering options considered that had potential for generating low-cost capacity consisted of the following:

  • Infill drilling of conventional new wells

  • Application of expandable tubular technology

For simplicity, the preliminary economics of the project were based on comparing the estimated cost of generating additional unit volume of gas in the field, referred to as cost of capacity (COC), for the different well engineering capacity measures. Weighing cost factors with technical feasibility, the study showed that solid expandable tubular installations provided a viable solution to the capacity-measures dilemma. For the expandable system to be a viable option, several factions of the industry had to perform extensive development or product enhancements. Enventure Global Technology enhanced their expandable system; Vallourec/Mannesman developed an expandable gas-tight connection; Halliburton Energy Services developed a pressure compensating system; and Shell evaluated materials and developed material specifications.

Addressing the Challenges

Further development of solid expandable tubular technology would provide cost effective conversions of existing wells. In addition, it would also help expedite the longer term goal of a cost effective monodiameter infill well. Many preplacement issues needed to be resolved before the actual installation in well Eemskanaal-2 (EKL-2) in the Groningen field.

The well chosen for this clad expansion produces sweet gas with sufficient CO2 to be corrosive to carbon steel; therefore, 13Cr was chosen for the production tubing. The same material, 13Cr, was chosen as the expandable clad liner.

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