مجله پژوهش نفت
پیاپی 132 (آذر و دی 1402)

Quantitative heterogeneity presentation is very important to compare the amount of heterogeneity in different reservoir characteristics in carbonate reservoirs. The aim of the present study is to quantify the heterogeneity by calculating the heterogeneity log and its application in investigating the heterogeneity of porosity and permeability in the Late Barremian-Early Aptian Darian carbonate Formation in the central part of the Persian Gulf. In order to calculate the heterogeneity logs, the well log data of gamma ray, bulk density, neutron porosity, acoustic and deep resistivity and the statistical methods of Lorenz coefficient and coefficient of variation have been used. Results show that the calculation of the heterogeneity log provides the possibility of quantitative comparison of the heterogeneity between different parts of the reservoir for different purposes. Heterogeneity calculation with both methods is efficient for calculating heterogeneity, but it should be noted that the coefficient of variation for the maximum heterogeneity does not have a specific range like the Lorenz coefficient. Also, increase in porosity is associated with a decrease in the amount of heterogeneity in the heterogeneity logs of deep resistivity, acoustic, neutron porosity and density. Unlike other logs, gamma ray heterogeneity log has little direct relationship with porosity in Darian Formation. Two types of neutron porosity heterogeneity and deep resistivity are the most used in determining the reservoir properties in this formation. Permeability shows a weak relationship with heterogeneity logs. In bioclast wackestone microfacies of carbonated units with high porosity, less heterogeneity is observed. Also, units with higher porosity are thicker and therefore exert stronger mean effects on heterogeneous areas. High variability in porosity and permeability causes higher heterogeneity. This is also the case about lithology and clay minerals. Heterogeneity changes at facies change boundaries. Therefore, heterogeneity log can be used to investigate geological heterogeneity, porosity, permeability and reservoir zoning.

In this study, the combination of two types of anionic and zwitterionic surfactants was used. By performing the phase behavior test, the optimal combination of two surfactants was found in such a way that the maximum amount of microemulsion of oil in water is formed. The obtained composition has caused stable nitrogen and CO2 foam in the Persian Gulf Sea water salinity and in contact with oil. Due to the use of zwitterionic surfactant, the stability of CO2 foam is 20.9% higher than that of nitrogen foam. By examining the half-life of CO2 foam by the foam column test, the half-life of foam at the optimal concentration was observed to be 145 minutes. The effect of functionalized carbon nanoparticles on the amount of microemulsion of oil in water and the stability of CO2 foam has been studied, and carbon nanoparticles with amine-carboxyl-hydroxyl functional group have performed best and foam stability has improved by 75%. Also, in order to ensure the performance of foam in dynamic conditions, CO2 foam injection was done in the micromodel, and with CO2 foam injection, 86.4% of the original oil was recovered. The use of carbon nanoparticles with amine-carboxyl-hydroxyl functional group improved the recovery of primary oil by 13.5% and 99.9% of primary oil was recovered.

Various industries’ waste, including polymer and waste sludge, can be released into the environment and cause irreparable damage. Therefore, their reuse in different fields is very important. This study focuses on the simultaneous use of waste polyethylene (PE), oily waste sludge (WS) resulting from the oil refining process, and micronized styrene-butadiene-styrene to improve the quality of base bitumen (PG58-22). Using the integrated variance optimal mixture design (I-OMD) method, which is used for the first time to optimize bitumen modification conditions, is the second goal of this project. The percentage composition of independent variables, including PE, SBS, and WS, were optimized based on several responses such as penetration (Pen), softening point (SP), ductility (Duct), retained penetration after short-term ageing (rPen), and change of mass after short term ageing (CM). Under the optimal conditions obtained for the modified bitumen, the rheological properties were studied. In the optimal conditions obtained using this method, the values of the independent factors PE, SBS, and WS were 3, 5, and 4% (wt/wt), respectively. Also, in the above optimal conditions, the response values of Pen, SP, Duct, rPen, and CM were 51 dmm, 64 °C, 27 cm, 83%, and 0.07%, respectively. In addition, under the above conditions, the rheological parameters of modified bitumen obtained from the bending beam rheometer and dynamic shear rheometer showed the characteristics of PG64-22 bitumen.

Decision-making to choose the best Enhanced Oil Recovery (EOR) method(s) among different variety of models, is a vital step in the oil reservoir development process. Selecting the proper EOR method has a key role in the technical and economic success of enormous oil industry projects. Screening criteria are used for selecting the best EOR method(s) for an oil reservoir with specific rock and fluid properties. The main input parameters that affect the screening process include; Reservoir capacity, fluid transmissibility and permeability, depth, net thickness, temperature, and oil gravity (API). Considering mentioned parameters have uncertainty, specifying a suitable EOR method for reservoir development is a radical challenge. It can be used combination of fuzzy logic systems (knowledge base) and artificial neural networks (data-driven) as a suitable tool and solution for expressing uncertainty and screening methods. In this study, data from the history of different reservoirs worldwide is used to define fuzzy variables and determine fuzzy rules between input and target variables, and finally, a fuzzy model and a single-layer neural network with 20 neurons are presented. ANN model provides 92% accuracy in the prediction of the target method. Consequently, we proposed the ensemble model for the selection of the EOR screening tool.

In this research, by studying 752 thin sections prepared from core and cuttings samples of two wells from the Mansourabad oilfield, nine microfacies were identified in a carbonate ramp type platform environment. Based on the description of the studied sections and petrography analysis, the most important diagenesis processes affecting the Asmari Formation were identified. According to the patterns of the facies change and well logs, five third-order depositional sequences (A to E) with the age of the Rupelian/Chattian to the Burdigalian were identified. Using the clustering method, five electrical facies were identified for both wells. One of the common methods to determine the flow units in the reservoir is the use of important and practical methods of indicating the flow unit zone using the modified Lorenz diagram methods. Using the FZI method on the estimated porosity-permeability data led to the identification of five hydraulic flow units in the well#8 and 6 flow units in the well#14. Moreover, by using the Lorenz method, six flow units for well#8 and three flow units for well#14 were identified using the porosity and permeability data estimated from the well log; which include speed, reservoir and baffle flow units. Based on the results of SMLP and the FZI methods of the estimated porosity and permeability, they provided the best and most complete separation method in this reservoir and are considered the most suitable method for determining rock types. By combining different methods in determining flow units, six and three flow units can be finally introduced for the Asmari Formation in the studied wells. The results of this study can be used in the development and better understanding of the Asmari Reservoir in the Mansourabad Oilfield.

In the present study, for the first time, the effect of pyrolysis temperature on the structure of carbon aerogel synthesized at ambient conditions as a support and methods of cobalt-doped carbon aerogel on its physicochemical properties have been investigated. Carbon aerogel was synthesized by resorcinol and formaldehyde precursors at pyrolysis temperatures of 550 °C, 700 °C and 900 °C and cobalt-doped carbon aerogel was prepared by the following three different methods (i) cobalt impregnation on the carbon aerogel, (ii) cobalt impregnation on the organic resorcinol-formaldehyde aerogel, and (iii) addition of cobalt precursor to the initial resorcinol-formaldehyde mixture before carbon aerogel polymerization process. The results indicated that pyrolysis at 700 °C led to mesoporous carbon aerogel with a specific surface area of 483.8 m2/g. High cobalt dispersion and particle size controllability have been seen in the impregnation method, while in the third method, the cobalt precursor catalyzes the polymerization process and leads to the formation of microparticles.

The most important challenges in water injection operation are mineral precipitation and inorganic scale formation .The formation of mineral scales in the pore throats of the reservoir rock results in reduction of permeability, porosity and production rate from the reservoir. One of the methods to solve this problem is to change the ions concentraion in the injected water. In smart water injection, the type and concentration of ions is particular importance in increasing the production efficiency and the recovery factor. In this article, based on the ion analysis of formation water and injection water samples in one of the oil fields in southwest of Iran, water compatibility test and effect scale formation on wettability alteration were studied experimentally. Moreover, simulation and sensitivity analysis of effective ions on strontium sulfate and calcium sulfate deposits were done. In order to identify the type and morphology of scales, SEM image and EDX analysis were used.  The results of the  water compatibility experiments show that increases in Sulfate ion with 4000 ppm causes the weight of the precipitates increased from 400 mg/L to 1400mg/L that sulfate ion with a ratio of 80 percent of injection water and 20 percent of formation water has the greatest effect on the reservoir damage and formation of strontium sulfate and calcium sulfate deposits. In the static tests of mixed waters, due to more investigation of scales in different parts of the reservoir and also the novelty of this research, scales were also investigated in the presence of rock in different conditions, and the weight of precipitates was observed from 800 mg/L to 1800 mg/L which indicates the surface absorption of ions by the rock and creat calcium carbonate formation.

Optimizing the placement of wells is a crucial step in field development as it directly impacts production and cost. Inappropriate well placement can lead to decreased production and higher costs due to the expensive drilling process. Vertical well placement focuses on optimizing wellhead coordinates (x and y parameters), while horizontal and deviated wells require considering the depth of the wells (z parameter) along with operational limitations. This research presents an automatic framework that utilizes the particle swarm optimization algorithm to optimize the location of horizontal wells, taking into account drilling limitations. The objective function used is the net present value (NPV). This framework defines the number of particle swarm optimization variables based on operational constraints and well geometry. The algorithm randomly selects parameter values and applies the optimization procedure while considering specific constraints until the stop criteria are met. The framework successfully optimized the x, y, z, LP (Landing point), and KOP (Kick of Point) parameters in two heterogeneous synthetic models and a benchmark model (PUNQ_S3). On average, the net present value increased by 22% in all models, with greater heterogeneity resulting in a higher increase compared to homogeneous models.

The Kangan and Dalan formations have long been considered as gas reservoirs due to their deep burial history. However, this study investigated the type of hydrocarbon fluid in these reservoirs based on the geochemical interpretation of mud gas logging and petrophysical evaluation in the Persian Gulf. The study was conducted in three stages. Firstly, well logs were evaluated under the assumption that the reservoir is an oil-type reservoir. In the next step, the type of fluid was identified based on the geochemical interpretation of mud gas logging, using the Haworth and Pixler methods. The final fluid type was determined based on the integration of geochemical methods. In the last step, a petrophysical re-evaluation was done in the susceptible oil zone. According to the primary petrophysical interpretation, there are three oil zones including K1, K2 and K4 in the reservoir. Meanwhile, based on the geochemical interpretation of mud gas logging, K1 and K4 zones are gas type and only the K2 zone contains oil-type hydrocarbon. Petrophysical re-evaluation of the K2 zone (identified as oil-type reservoir zone) indicated an effective porosity of 6% and water saturation of 29%. The results of this study suggest that paying attention to mud gas logging interpretation when determining the appropriate interval for perforation and selecting the appropriate zones for reservoir tests can reduce drilling costs and time.

In the process of extracting gas and condensate from the seabed, we often encounter a multiphase flow. Multiphase fluid flow to pass through the transmission pipes requires the separation of outgoing water from the formation on offshore platforms in order to eliminate corrosion effects in downstream facilities such as refinery. Formation water often enters the sea after separation. Water monitoring of the formation in terms of salinity is an important part of the process of measuring the volumetric rate of multiphase flow components at the separator site by single-phase metering systems. Considering the high dependence of parameters such as density, viscosity and electrical conductivity of fluid to salinity level, we decided to investigate the possibility of conceptual design of formation water salinity system based on gamma technique. The change in the key characteristics related to the gamma beam shaping module emitted from the cobalt-60 radioactive source and with the consideration of radiation safety of personnel, it was obtained the optimum geometric and dimensional conditions of the collimator in order to achieve maximum accuracy in different amounts of salinity fraction of sodium iodide salt in water measurement.