Simulating a Steamflood at the Georgsdorf Field, Federal Republic of Germany (includes associated papers 13965 and 14471 )
Authors: Sobocinski D.P. , Leskova Horst , Greebe Frans 
Published: December 2007

This paper describes the use of a black-oil thermal simulator to evaluate the performance of an ongoing steamflood at the Georgsdorf reservoir in the Federal Republic of Germany. An areal model was developed to represent about 1.2 × 10(6) m2 [300 acres] of the steam flood and the adjoining area where wells are located on irregular spacing. Ten years' historical performance, including six years' steam injection, were history matched to calibrate the model. The calibrated model then was used to study the future depletion of the reservoir under several options. This information was used by Gewerkschaften Brigitta und Elwerath Betriebsfuhrungs GmbH (BEB), the operator, to help make decisions about the future operation of the steam flood.

Introduction

Reservoir engineering was defined by Moore as the "artof developing and producing oil and gas fields in such a way as to obtain a high economic recovery." In practicing this art, the repeated objectivity of reservoir simulation can avoid the subjective distortion of analytical procedures. However, the art becomes increasingly abstract when simulation is applied to reservoir processes involving nonisothermal operations and other complex phenomena.

This paper is concerned with the use of a thermal reservoir simulator to assess the historical performance of anon going steam flood at the Georgsdorf field so that possible future operating options can be evaluated. Such information can assist management in decidinghow much steam is required in certain areas,how the steam flood might be expanded, andwhere new injection wells and infill producers might be located.

No analytical procedures exist to evaluate the displacement of oil by steam and water adequately in a complex geological setting where wells are drilled on irregular spacing. Thermal reservoir simulation provides this capability, but applications of such simulators can be impractical to justify, especially for smaller projects.

The literature is replete with information about simulating conventional fluid displacement in isothermal systems. Substantially less is available for simulating on isothermal, chemical, and miscible processes. Coats cited much of the pertinent simulation technology and put this information into perspective in his 1982state-of-the-art paper. There is little published information on specific applications of thermal simulation. Chu and Trimble used a three-dimensional (3D), three-phasenumerical simulator in the black-oil mode to history match5 1/2 years' performance for a steam stimulation pattern in the Kern River field, CA. The model subsequently was used to optimize operating parameters. Gomaa et al. also used a black-oil thermal simulator to model elements of an inverted five-spot pattern to determine the relative importance of various steam flood and reservoir parameters for the Monarch sand in the Midway-Sunset field, CA. Munoz simulated steam flooding in the Tia Juana M-6Project, Venezuela. In this work, a 3D model was prepared for an element of symmetry in a regular inverted seven-spot. These studies addressed the effects of permeability variations, gravity segregation, and positions of completion intervals. Williams prepared a 3D model with which he determined the response to production by steam stimulation and steam displacement in the steeply dipping North Midway field, CA. Another 3D study of a steeply dipping reservoir was reported by Moughamian et al. This work provided information used to design a steam flood in the heavy-oil bearing Webster sand sequence in the Midway-Sunset field.

All the studies mentioned treated a representative segment or an element of a repeated pattern where either steam stimulation or steam displacement was contemplated. All the studies provided important ideas about simulation methodology but none dealt with fieldwide simulation of ongoing steam floods with irregularly spaced wells.

The Georgsdorf Field

Lillie and Springer discussed the technical and economic aspects of a steam flood in the Georgsdorf field. Somepertinent reservoir description information from this paperis repeated for convenience.

The Georgsdorf field was discovered in 1943 and developed largely between 1946 and 1963 by the drilling of about 350 wells. BEB operates the field for aconsortium of companies that includes itself, C. Deilmann A.G., Preussag A.G., and Wintershall A.G. Each company owns 25% of the field.

The Valanginian sandstone of lower Cretaceous age is a good quality reservoir throughout much of Georgsdorf.

JPT

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