Journal of Oil, Gas and Petrochemical Technology
سال هشتم شماره 1 (Winter and Spring 2021)

In order to minimize the greenhouse gas emissions (GHG) over the world, the process of CO2 capture and storage started in Salah Gas project (ISG). Here, the CO2 is sequestered in an onshore saline aquifer as a long-term process and storage to eliminate vent to atmosphere and ensure a safe storage for hundreds of years. This paper describes the amplified geochemical imaging AGI technique as a new technology among others for CO2 monitoring presented in the 79th EAGE Paris Conference and Exhibition in 2017. The AGI technique aims to monitor the tracer gases injected in 2007 at Krechba field to detect possible CO2 leakage to the surface. To garantee the underground sequestration, the Amplified geochemical imaging AGI survey was used for the first time as a surface geochemical imaging to detect and quantify organic compounds from C1 to C20 (pythane). The AGI is a new technique based on the chemical analysis and sophisticated statistical geochemical methods to differentiate between the accumulated reservoir hydrocarbons originated from the mother source or migrated oil. The main objective of the present study is to present in details the AGI technique from the implementation and design to the inetrpretaion of the sample signatures.

Underground gas storage (UGS) in depleted reservoirs holds the highest amount of working gas. In this study, Anhydrite caprock of an Iranian depleted reservoir was studied due to an increase in the number of seismic activities around this field. Anhydrite mechanical properties degrade due to cyclic loading effects resulted from the natural gas injection-production mechanisms. Anhydrite specimens were cored from the outcrop samples. The similarity of Anhydrite outcrop and drilling cuttings was confirmed using X-ray diffraction and SEM EDAX mineral analysis. The effect of cyclic loading on Anhydrite specimens has  not been studied previously. The specimens loaded 10, 20, and 30 times in the range of 18, 21, 24, and 25 MPa respectively. Anhydrite unconfined compressive strength (UCS) reduced between 3.5 to 23.9 percent under the cyclic loading experiments. The UCS is more sensitive to the intensity of loading rather than the cyclic times. The specimens CT images were obtained before and after the cyclic loading tests. Also petrophysical properties of the specimens were measured. The study of the specimens’ damage indicated that the anhydrite loading threshold was greater than 40 percent of the original UCS.

A series of Fe2O3(83%)-ZrO2(7.5%)-Al2O3(7%)-CeO2(2.5%) catalysts were synthesized with co-precipitation method in different aging times (0 to 6 hours) using the metal nitrate precursors. Physicochemical properties of the prepared catalysts characterized with X-Ray Diffraction (XRD), Field Emission Scanning Electron Microscopy (FE-SEM), EDX, Nitrogen Adsorption-Desorption, Thermal gravimetric analysis (TGA) and H2-Temperature programmed reduction (H2-TPR) analyses. The catalytic performance of the synthesized catalysts was also evaluated by the steam catalytic cracking of the Vacuum bottom (VB). The results showed that increasing the aging time improved the textural properties of the catalysts in the oxygen adsorption capacity from steam, as well as the control of the catalyst surface area to produce a higher quality liquid product. When Cat-6 (catalyst with aging time of 6 h) was used as the catalyst, the yield of gasoline cut (boiling point range 27-225 ), diesel cut (boiling point range 200-320 ) and VGO cut (boiling point range 320-450 ) production was 25.3 mass %, 47.7 mass % and 33.8 mass %, respectively. Furthermore, Cat-6 showed higher performance in the partial oxidation of VB.

As a commercially available biodegradable and bio-based polymer, Poly (lactic acid) is accepted to be a promising potential to replace conventional polymers in packaging applications. Oriented PLA films are obtained through stretching at temperatures above the glass transition temperature. The present study evaluates the effects of both temperature and drawing speed during stretching on the tensile behavior and surface morphology of PLA films. Increasing the drawing speed enhances the strain hardening behavior. Conversely, there is a noticeable reduction in strain hardening as stretching temperature increases from 70 to 80 °C. Besides, stretching at 90 °C eliminates, thoroughly, the strain hardening behavior at lower drawing speeds. However, stretching the PLA film at 90 °C and at a high drawing speed (30 mm/sec) stimulates the strain hardening behavior demonstrating chain extension exceeds the chain relaxation at such a high drawing speed. The surface morphology of PLA films observed by scanning electron microscopy (SEM) reveals no crystalline structures on the film surface of PLA films stretched at 70 and 80 °C. The SEM image of PLA film stretched at 90 °C indicates formation of crystalline lamellae which is attributed to cold crystallization during stretching.

The study of flow through porous media has been of cardinal gravity in various oil and gas applications like enhanced oil recovery (EOR), acidizing, fracturing, etc. In apprehension to this need, core modeling has become prevalent to understand the flow through porous media. Hence, our study is aimed at simulating and analyzing the effect of surfactant flooding through anisotropic permeability conditions in a subsurface environment. The simulations were carried out on a 2-D model of the experimental core and were finely meshed for the better convergence. The natural anionic surfactant extracted from Madhuca longifolia oil and Partially Hydrolyzed Polyacryl Amide polymer referenced for the physicochemical properties were used in the simulations. Several sets of directional permeabilities were introduced vertically and horizontally for a single absolute permeability and porosity system. Results indicated to a trend of oil recovery upright with increasing vertical permeability. A lower areal sweep efficiency and early breakthrough were observed in models with high horizontal permeabilities. With the ingress of computational fluid dynamics in the oil and gas industry, a more comprehensive understanding of flow patterns allows improved EOR process designs. Our research exploited this to model the multiphase flow through an anisotropic permeability medium and its effect on the oil recovery.

Carbonate reservoirs are more complex than the conventional sandstone reservoirs. This is because many carbonate reservoirs have a fractured network which results in a varied distribution of porosity and permeability. Oil recovery from such reservoirs is challenging because the injected fluid tends to flow through the fractured formations rather than through the oil-wet matrix. In this research, the concept is to plug the fracture network using biopolymer Xanthan Gum (XG), and then modify the wettability of the carbonate rock towards a water-wet system using a biosurfactant. Scanning Electron Microscopy (SEM) was employed to approve the presence of the biosurfactant RL and biopolymer XG at the rock surface. The results revealed that oil recovery increased by up to 7-9% in the oil-wet fractured carbonate cores using the biopolymer / biosurfactant / water flooding. In the proposed mechanism using the biopolymer flooding, the fractured zone was temporarily plugged (reducing fracture permeability by 18%) which caused an improvement in the water imbibition process.