Fracture Permeability Evaluation in Bouri Field

By

 E. Caselgrendi¹, F. Marchini¹, M. Ghedidda²

(1) ENI-Agip Division, S. Donato Milanese (Milan), Italy (2) Agip Oil Comp. Ltd, Tripoli, Libya

 Aim of this paper is to describe the methodology applied to the study of fracture permeability in Bouri field (Libyan offshore). In this field, fractures give an important contribution to productivity. This is evident considering well tests interpretations; moreover, dynamic data show how the intensity of the fractures decreases far from the main discontinuities.

In the past these phenomena had been modelled using permeability multipliers near the faults and in correspondence of the wells with high Kh. This approach involved a remarkable uncertainty in the western zones where well data are few; therefore a different methodology has been tuned.

This methodology is based on the interpretation of data coming from different sources: 3D seismic, well tests and core analyses. The first phase was the creation of a database comprising the geometric characteristics of the faults; then they have been analysed to point out homogeneous groups. The next phase was the analysis of the spatial distribution of the faults (seismic and subseismic) and led to the processing of a fracture intensity map (P21). Then P21 average value has been calculated for all the wells on a circular area whose diameter is function of the drainage radius of the well itself. The P21 values obtained have been correlated with permeability from tests and cores. Based on this correlation, permeability maps were drawn and they have been introduced into the dynamic simulator. A satisfactory history match has been obtained in a shorter time through minor changes.