Practical Approach in Modeling Naturally Fractured Reservoir: A Field Case Study

Abstract

TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractThis paper presents a practical approach in modeling a naturally fractured reservoir. The approach was used for a field study of a giant carbonate reservoir in the Middle East. The method is shown to be practical and comprehensive and yet has produced good results. It consists of a fully integrated effort from geological, geophysical and engineering disciplines. The overall goal of the study is to develop a representative reservoir model to form the basis for reservoir management and long-term development planning.The approach consists of the following procedures:• Generation of multiple realizations of matrix property using geostatistical techniques. The standard cosimulation procedure was implemented to ensure the consistency among reservoir properties, namely rock type, porosity and permeability. • Generation of multiple realizations of 3D fracture property by reconciling seismic, well logs and dynamic data. These were obtained from curvature analysis and seismic facies map validated by borehole image and dynamic data. The fracture network was described in the reservoir as lineaments (fracture swarms) showing two major fracture trends. • Calibration of the model permeability with well testderived permeability considering fracture distribution. A newly developed technique was implemented to ensure that the fine scale model (i.e., geological model) honors well test as well as production data before it was subjected to the flow simulation. The technique also generates permeability anisotropy to account for fracture orientations.• Ranking of multiple realizations using streamline simulation to select three representative realizations (low, medium and high models).• Upscaling of reservoir properties, including vertical upscaling level optimization using streamline simulation. • History matching and future performance prediction of the three selected realizations as a single media model. The use of single media model was based on the observation of relatively high matrix permeability in the major producing zone. However, for comparison purposes, a dual media model was also developed.• Uncertainty analysis of the future dynamic performance using a probabilistic approach. The procedure described above has been implemented successfully in a field study. The use of a calibration process in the geological model reduces the number of parameters that need to be adjusted during history matching. Consequently, history matching may concentrate on the uncertainty in parameters that have not been specifically accounted for in the geological modeling stage, such as relative permeability and aquifer size/strength.

A new methodology to reduce uncertainty of global attributes in naturally fractured reservoirs

“…To reduce the high computational effort required by naturally fractured reservoirs, some works proposed the streamline-based approach (Vasco et al, 1997;Bahar et al, 2003) Similarly, De Lima et al (2009) proposed the application of connectivity analysis to characterize well-reservoir and well-to-well connectivity in fractured reservoirs. Again, the authors worked only on the simulation model while we use the geological and simulation models.…”

An Innovative Approach To Integrate Fracture, Well Test and Production Data into Reservoir Models

“…The approach used in the study was a stochastic approach where multiple reservoir descriptions were generated to quantify the uncertainty in the future performance. 1,2 Reservoir properties for each realization were generated using a geostatistical technique that produces properties, i.e., porosity, permeability and water saturation, consistent with the underlying rock type description. The description was based on core and log data.…”