Description of Groningen Gas Well Performance Suitable for Medium and Long Term Planning
Authors: Lingen P.L. 
Published: December 2007

This paper was prepared for the SPE-European Spring Meeting 1974 of the Society of Petroleum Engineers of AIME, held in Amsterdam, the Netherlands, May 29–30, 1974. Permission to copy is restricted to an abstract of not more than 300 words. Illustrations may not be copied. The abstract should contain conspicuous acknowledgment of where and by whom the paper is presented. Publication elsewhere after publication in the JOURNAL OF PETROLEUM TECHNOLOGY or the SOCIETY OF publication in the JOURNAL OF PETROLEUM TECHNOLOGY or the SOCIETY OF PETROLEUM ENGINEERS JOURNAL is usually granted upon request to the Editor PETROLEUM ENGINEERS JOURNAL is usually granted upon request to the Editor of the appropriate journal provided agreement to give proper credit is made.
Discussion of this paper is invited. Three copies of any discussion should be sent to the Netherland Section of the Society of Petroleum Engineers, P. O. Box 228, The Hague, the Netherlands. Such discussion may be presented at the above meeting and, with the paper, may be considered for publication in one of the two SPE magazines.

Abstract
Long-term development studies for the Groningen gas field call for a well-performance description which is valid for all future reservoir pressures.
The performance of every producing well in the Groningen gas field is usually tested once a year. In such a routine test the wellhead pressures are measured with the well producing at different flow rates.
In order to extrapolate the performance measured to lower reservoir pressures, use is made of a theoretical well model which is matched to the results of the well test. The theoretical description of the well-performance consists of analytical equations which describe the inflow, the interference and the vertical flow in a dry gas well. Two groups of pressure independent well and reservoir characteristics, incorporated in the equation describing the inflow performance, are used as matching parameters. parameters. Thus derived, the well-performance description is not only accurate for medium- and long-term planning, but it also gives an idea of the inflow performance of a well, without flowing bottom hole pressure surveys being necessary.

Introduction
The Groningen gas field (proven ultimate recovery 1,900 × 10(9) m3) was discovered in 1959. The location of the field in the north east of Holland is shown in figure 1. The reservoir, lying in the Rotliegendes Sandstone at a depth of about 3,000 m, is mainly bounded by faults and is also in contact with a number of limited aquifers. In the structurally high south the reservoir is completely dry, whereas in the northern part the gas is underlain by bottom water. The permeability of the gas zone is several hundred mD. In general the net gas-sand thickness exceeds 100 m.
On the basis of these favourable reservoir properties it was decided to drain the reservoir properties it was decided to drain the reservoir by wells grouped together in clusters, thus economizing on surface facilities. The first 14 clusters were set up in the dry southern part, each cluster consisting of 8 wells with an initial combined capacity of about 14 million m3/d. The later clusters were located in the centre of the field, each having, an initial capacity of about 24 million m3/d, obtained with 11 wells.
The lay-out of a cluster is shown in figure 2. The gas flows from the wells through individual flow lines to a central manifold. It is dried in five dehydration plants placed in parallel. parallel.