Producing From Exploration Wells
Authors: Romano Christian 
Published: December 2007

Temporarily producing a well or wells allows extended testing for evaluating a reservoir before incurring large additional drilling expenses to develop afield. It is also useful for determining the capacity and specific process a permanent production facility should have if one is justified. As an additional benefit, such production provides cash flow early in a field's development cycle; even at the exploration stage.

For these reasons, the use of temporary facilities for early production and extended well testing is increasing, both on- and offshore. In response, standardized modules and process skids that can be kept in stock to shorten delivery lead time were developed. As a result, the time typically needed to design, fabricate, and install a 10,000- to 40,000-BOPD early production facility (EPF), such as the one in Fig. 1, has been reduced to 14 weeks. This standardization permits capacity to be added or cut back as required, makes mobilization faster and easier, lowers upkeep and maintenance costs through improved reliability, and often saves transportation costs by allowing shipment from fabrication site to wellsite by common carrier.

An EPF constructed from such standardized modules can be configured to fit practically any available space. This allows a facility for offshore use to be installed on a semisubmersible, jackup rig, barge, floating production platform, production jacket, or tanker. For use on land, a modular EPF can be mounted on skids or trailers.

If the EPF must be transported a relatively long distance or installed at a remote site, the overall time required will exceed the typical 14-week period, but not by a large margin. As an example, an EPF made up of standardized modules was recently designed, prefabricated, and transported to and installed on a semisubmersible rig drilling in the Machar field in just 19 weeks from the time the operator approved the project. The Machar field is on Block 23/26a in279 ft of water in the U.K. sector of the North Sea [110 miles east of Aberdeen.

This EPF, which is processing the produced fluids from two wells for reservoir evaluation, has a standard capacity of 20,000 BOPD. However, owing to customization and the properties of the Machar crude, actual sustained production is 30,000 BOPD, with two-stage separation of gas and oil. The gas is flared with two 60-ft booms with low-pressure flare tips and a high-pressure flare tip on the 150-ft-high derrick. Processed oil is stored on a dynamically positioned tanker that is linked to the EPF on the semisubmersible rig by a0.62-mile subsea flow line.

This discussion has concentrated on the use of modular EPF's to provide reservoir evaluation information and cash flow during exploration and early stages of field development. However, it should be noted that EPF use is not limited to such situations. For example, it is not uncommon for an EPF to be used to produce a marginal field offshore because a full-scale permanent production facility would be prohibitively expensive in relation to the anticipated return on investment. In this type of application, the EPF is often called a mobile production facility (MPF). Whether called an EPF or MPF, this fast-track approach minimizes negative cash flow while allowing a decision on field development to be made at a later time.

bblx1.589 873 E-01 =m3

ftx3.048* E-01 =m

milex1.609 344* E+00 =km

*Conversion factor is exact.

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