Petrophysical and geomechanical characterization of the Late Cretaceous limestone reservoirs from the Southeastern Constantine Basin, Algeria

Abstract

We have characterized the petrophysical and geomechanical properties of the Late Cretaceous Turonian and Cenomanian carbonate reservoirs from the southeast Constantine Basin, northern Algeria. In general, Turonian carbonates exhibit a wide range of porosities (2%–15%) and permeabilities (0.001–10 mD), whereas the Cenomanian reservoir appears to be very tight (<6% porosity and <0.1 mD permeability). Based on their storage and hydraulic flow characteristics, these carbonates were classified into two distinct reservoir rock types (RRT): RRT-I is hosted by nano- to microporosities that displays poor reservoir qualities compared to the RRT-II, consisting of mesoporous Turonian intervals (>10% porosity and 0.5–10 mD permeability). The reservoir pore-pressure gradient is interpreted to be a little above the hydrostatic (0.51 psi/ft), whereas the minimum horizontal stress (Sh) has a 0.72 psi/ft gradient. In situ stress analysis establishes a dominant strike-slip tectonic stress field in the basin. Shale intercalations associated with the carbonate facies are characterized by comparatively high failure pressure that can lead to wellbore failures, which may be avoided considering the recommended minimum drilling mud weight as obtained from the rock failure criterion. Extensive wellbore breakouts (C-quality) were observed in the acoustic image logs recorded in the studied reservoir intervals, inferring a mean maximum horizontal stress azimuth of 350°N. We recommend that deviated wells in the direction of the interpreted Sh orientation (approximately east–west) using hydraulic fracturing can be useful to attain optimum wellbore stability and effective permeability enhancement. Our findings have significant implications for enhanced production within the tight carbonate reservoirs situated in a strike-slip domain.

Geomechanical and Petrophysical Assessment of the Lower Turonian Tight Carbonates, Southeastern Constantine Basin, Algeria: Implications for Unconventional Reservoir Development and Fracture Reactivation Potential

“…The Constantine Basin is situated in the southeastern part of the Saharan Atlas, northern Algeria, close to the Tunisian border [4,9] (Figure 1). The Saharan Atlas is separated from the Saharan platform by the South Atlas fault, which marks the southern boundary of the studied basin.…”

“…The studied well locations are marked by red circles. Black lines indicate regional structural trends (refer to Baouche et al [9] for structural trends).…”

“…We inferred the formation pore pressure (PP) from direct measurements. Vertical stress (Sv) and minimum horizontal stress (Shmin) are adapted from Baouche et al [9], who also provided maximum horizontal stress (SHmax) from poroelastic models, but the estimated output was not calibrated. However, in this study, we have employed a stress polygon approach based on our image log-based observations, which constrained the SHmax in a more confident manner.…”

Comparing the performance of machine learning methods in estimating the shear wave transit time in one of the reservoirs in southwest of Iran

“…By using geomechanical modeling, it is possible to analyze and predict rock behavior in different reservoir conditions and oil and gas-related issues according to shear wave velocity and other relevant parameters, including rock density and resistance. For example, geomechanical modeling can be used in the analysis of reservoir pressure, rock fractures, crumpling of drill pipes, surface subsidence, and reservoir compaction, optimal design of well stimulation operations such as hydraulic fracturing, as well as simulation of rock behavior in porous environments 5 , 6 . As a result, accurate estimation of shear wave velocity is very important in geomechanical modeling and enables petroleum engineers to gain a complete understanding of rock properties and reservoir performance.…”

In Situ Stress Determination Based on Acoustic Image Logs and Borehole Measurements in the In-Adaoui and Bourarhat Hydrocarbon Fields, Eastern Algeria

“…However, image logs are one of the best ways to confidently infer and constrain S HMax magnitudes from borehole failures. Previous researchers worked on the geomechanical aspects of various Algerian hydrocarbon provinces, i.e., Illizi Basin [3,4,9,12,13], Oued Mya Basin [14], Constantine Basin [15,16], Berkine Basin [17], and the Hassi Messaoud fields [18]. The geomechanical characteristics and in situ stress magnitudes and orientations in the In-Adaoui and Bourarhat hydrocarbon fields are vital for field development and future hydraulic fracturing, but no prior studies have been conducted in this area, which sets the premise of this study.…”