Fracture Identification and Comprehensive Evaluation of the Parameters by Dual Laterolog Data

Abstract

Quality and productivity of tight formations are heavily dependent on the degree of fracture development. In fact, hard and dense carbonate formations may not be considered as net pay without presence of fractures which conduct fluids towards wellbore. The evaluation of fractures is a key to reservoir effectiveness characterization for well drilling, completion, development and simulation of fractured reservoirs. Although new imaging technologies such as Formation Micro-Scanners and Imagers (FMS and FMI) provide the information of fracture properties (dip angle, porosity, aperture and permeability), image logs are very expensive and cannot be available in all wells. In this paper, fracture parameters are estimated using conventional Dual Laterolog (DLL) resistivity, which includes shallow (LLS) and deep (LLD) responses. This technique is based on electrical resistivity anomalies because of separation of shallow and deep laterolog curves. Fracture parameters that can be calculated by DLL include dip angle, aperture, porosity, permeability and cementation factor. The accuracy of the calculated parameters using DLL is validated by the results of FMI in one well in one of Iranian fractured reservoirs. Despite the image logs, the conventional DLL is routinely run in all of the drilled wells. This makes the constructed fracture model on the basis of DLLs more reliable than the corresponding model founded on limited and insufficient image logs. Furthermore, DLL has an advantage of much deeper evaluation of fractures in comparison with the immediate borehole investigation of image logs.

Reservoir heterogeneity and fracture parameter determination using electrical image logs and petrophysical data (a case study, carbonate Asmari Formation, Zagros Basin, SW Iran)

“…However, the appearance for closed or filled fractures is resistive if the filling materials are dense like calcite or anhydrite. In some cases, full set logs such as PEF, RHOZ, resistivity logs and NPHI are very useful for such kind of differentiation (Saboorian-Jooybari et al 2015;Tokhmchi et al 2010). It is noteworthy that fracture aperture is only measurable using some electrical imaging tools (not all image logs) for open fractures.…”

Automatic History Matching for Adjusting Permeability Field of Fractured Basement Reservoir Simulation Model Using Seismic, Well Log, and Production Data

“…The largest of FBRs in Vietnam is Bach Ho located in Cuu Long Basin [3]. Many studies have conducted overviews of geological and production characteristics for FBRs [4,5]. These studies have shown that FBRs have low matrix porosity and permeability and that fluids are mainly stored and flow in natural fractures.…”

Data-driven model for shear wave transit time prediction for formation evaluation

“…This is due to the fact that the sonic transit times are affected by reservoir properties that include compaction, porosity, anisotropy, density, lithology, cementation, consolidation, overburden stress and pore pressure (Khazanehdari and Mccann 2005;Krief et al 1990;Thomsen 1986;Toksöz et al 1976;Williams 1990). A good understanding of how these properties change over the life of the reservoir is essential for proper reservoir planning, development and management (Dakhelpour-Ghoveifel et al 2019;Khazanehdari and Mccann 2005;Saboorian-Jooybari et al 2015).…”

“…Well-calibrated and reliable sonic logging tools are necessary to acquire accurate measurements of compressional and shear wave transit time, otherwise, the formation evaluations and estimation become false and misleading (Onalo et al 2018a. Typical anomalies observed in well logs have been presented in the literature (Saboorian-Jooybari et al 2016. This may result in the development of non-potential reservoirs and the abandonment of potential reservoir formations.…”