Integrated Stochastic Inversion Approach Assessing Thin Reservoirs Full Potential in the Prolific Oil-Prone Periphery of Hassi Messaoud Field, Algeria

Nowadays it become harder, risker and more expensive understanding the reservoir potentiality and design the optimum development plan for challenging thin reservoirs. In a geological complex area, integrated seismic reservoir characterization approach was crucial to unlock the potentiality for the study area, which is located at Oued Mya basin, SE Saharan platform Algeria. Seismic data analysis is one of the key procedures for characterizing reservoirs and monitoring subsurface properties. Integration of seismic stochastic inversion and geological model will help to demonstrate the link between seismic and reservoir properties more quantitative. The seismic data of region were challenging, with around 30 wells drilled over 400 Km2. To overcome the challenges, the available geological and geophysical data were integrated to construct the reservoir characterization study and reduce drilling uncertainty. Ensure the reservoir characterization process was constrained by a robust workflow and consistent with the available geophysical, geological, and petrophysical data. Petrophysical interpretation, seismic interpretation, rock physics analysis and Stochastic Inversion processes were carried out. These processes were integrated to characterize the lateral and vertical extent of the lithofacies in five stacked reservoirs across the area of interest to identify the potential delineation of thin reservoirs of nine-meter thickness.

Stratigraphic and sedimentological characterisation of the Late Cretaceous post-rift intra Lange Sandstones of the Gimsan Basin and Grinda Graben (Halten Terrace, Norwegian Sea)

Deep-marine gravity-driven deposits represent one of the more investigated depositional systems due to their potential interest as target for exploration and carbon capture and storage activities, as well as an important record of the depositional history of a basin through time. Although the Halten Terrace (Norwegian Sea) is one of the main successful exploration areas, we still have poor understanding of the post-rift Cretaceous interval. Here, 3D seismic reflection and borehole data are integrated to investigate the stratigraphic distribution and sedimentological characteristics of the Cenomanian-Turonian intra Lange Sandstones in the Gimsan Basin and Grinda Graben. The Lange Formation records the deposition in a deep-marine environment of a thousand meter thick shale unit punctuated by tens of meters thick gravity-driven coarse-grained sandstone intervals sourced from the Norwegian mainland. The presence of gravity-driven deposits and the deep-marine setting is supported by seismic interpretation, architectural elements and the facies analysis of cored material acquired within the studied stratigraphic interval. Borehole data indicate the presence of both turbidites and hybrid-event beds rich in mud content. The results of this study have implications for the understanding of the distribution and reservoir potentiality of the Late Cretaceous Lange Formation in the Halten Terrace.

Petrophysical Investigation of the Khurmala Formation in Taq Taq Oil Field, Zagros Folded Belt

The Tertiary rocks of Khurmala Formation in the Taq Taq oil field have been studied using wireline log analysis, drilling cutting descriptions with integration of mud logging report, and test results for understanding reservoir potentiality and fluid distribution. The formation comprised dolostone and dolomitic limestone with an intercalation of clay layers between the recognized beds. The formation has variable thickness throughout the field, 99.8 m from the northeastern limb and 109 m in the southeastern plunge. The calculated shale volume in the studied interval shows a high rate of the clay contents which in some points the gamma ray has 100% of shale. The corrected log-derived bulk porosity subdivided the Khurmala Formation into 5 porosity units from the top to the bottom including (Kh-1, Kh-2, Kh-3, Kh-4, and Kh-5). The first (Kh-1), third (Kh-3), and fifth (Kh-5) porosity units have the average porosity ≥0.10 (10%) that can be considered as good reservoir unit in terms of porosity, whereas the shale contents reduced the reservoir quality of these units. However, well hydrocarbon entrapment through interconnected fractures and fault in the other Tertiary reservoir was recorded in Taq Taq field , but the weak connectivity of the pores in the Khurmala Formation caused this rock interval remains as water bearing zone.

Reservoir Characterization and Modelling with Diagenetic Trends of carbonates of the Kawagarh Formation: A Section exposed in the Kala-Chitta Range, Pakistan

Present study is focused on the diagenetic studies and reservoir characterization of the Cretaceous KawagarhFormation exposed in the Gandab village, Kala-Chitta range, north-western Himalayan Fold-and-Thrust belt, Pakistan.The formation is composed of argillaceous limestone and dark grey marls. A total of thirty-three representativecarbonate rock samples were collected at equal intervals of three meters. Various diagenetic features includingcementation, micritization, pyrite precipitation, neomorphism, fracturing, sparitization and stylolitization were observedin the studied rocks which occur in the marine, meteoric and deep burial diagenetic environments respectively. Suchdiagenetic features control the reservoir quality of the rock unit. Porosity types include mostly vuggy and fracture,while minor stylolitic porosity were noted with quantity ranging from 2.66% to 3.88%. The carbonates of KawagarhFormation are highly fractured, but the filling of these fractures due to precipitation of calcite or micritic mud hasgreatly reduced its reservoir potential, while some unfilled fractures, stylolites and vuggs are the dominant factors thatenhance the reservoir potentiality of the Kawagarh Formation. However, the porosity values still do not mark the levelof reservoir rock. These diagenetic studies revealed very less chances for hydrocarbon accumulation as no significantporosity values have been observed and overall reservoir potential is characterized as poor.

Reservoir Characterization and Modelling with Diagenetic Trends of carbonates of the Kawagarh Formation: A Section exposed in the Kala-Chitta Range, Pakistan

Present study is focused on the diagenetic studies and reservoir characterization of the Cretaceous KawagarhFormation exposed in the Gandab village, Kala-Chitta range, north-western Himalayan Fold-and-Thrust belt, Pakistan.The formation is composed of argillaceous limestone and dark grey marls. A total of thirty-three representativecarbonate rock samples were collected at equal intervals of three meters. Various diagenetic features includingcementation, micritization, pyrite precipitation, neomorphism, fracturing, sparitization and stylolitization were observedin the studied rocks which occur in the marine, meteoric and deep burial diagenetic environments respectively. Suchdiagenetic features control the reservoir quality of the rock unit. Porosity types include mostly vuggy and fracture,while minor stylolitic porosity were noted with quantity ranging from 2.66% to 3.88%. The carbonates of KawagarhFormation are highly fractured, but the filling of these fractures due to precipitation of calcite or micritic mud hasgreatly reduced its reservoir potential, while some unfilled fractures, stylolites and vuggs are the dominant factors thatenhance the reservoir potentiality of the Kawagarh Formation. However, the porosity values still do not mark the levelof reservoir rock. These diagenetic studies revealed very less chances for hydrocarbon accumulation as no significantporosity values have been observed and overall reservoir potential is characterized as poor.