The Fracture Characterization and Fracture Modeling of a Tight Carbonate Reservoir:The Najmah Sargelu of West Kuwait

摘要

This paper presents an innovative and promising, multidisciplinernintegrated approach that includes geology (BHI,rncores, wireline logs), geophysics (seismic facies analysis), andrnreservoir engineering data (production data, PLT, welltest)rnthat were combined to identify the main types of fractures, tornpredict their occurrence in the reservoir and to determine thernhydraulic properties of the different fractures setsrnThe Najmah – Sargelu of West Kuwait is an oil bearingrnreservoir made of tight carbonates where porosity andrnpermeability is mainly provided by the fracture network. Inrnthis paper, we will first introduce the method used to identifyrnand predict the two main scales of fractures: joints and largescalernfractures (faults and fracture swarms). The shale contentrn(Vshale) and mechanical beds thickness were found to be therntwo main geological drivers on joints occurrence. Thickness ofrnindividual beds were recorded from BHI acoustic imagesrnwhich enabled to measure an S/T ratio (fracture spacing to bedrnthickness) for each fracture set and for different shalyness.rnSecondly, we used an innovative solution to deliver anrnaccurate map of large-scale fractures location. This approachrnuses concurrently a set of selected fracture relevant attributesrnin a multi-variable statistical process called Seismic FaciesrnAnalysis (SFA).rnA 3D stochastic fracture model was then generatedrnincorporating the two scales of fractures and constrained byrnthe reservoir shalyness, the S/T ratio and the seismic faciesrnmap. The calibration of the hydraulic properties of thernfractures was achieved through the second innovationrnpresented in this paper: the simulation of a synthetic well testrnusing the 3D fracture model and matched with the real data.rnThis resulted in the calibration of the hydraulic fracturesrnconductivity for each fracture type. These values wererncombined with the 3D stochastic fracture model to produce 3Drnfracture properties models (porosity, permeabilities and blockrnsize) for the Najmah – Sargelu of West Kuwait.