Petroleum Research最新文献

While computer modeling of annular displacement efficiency is widely applied in cementing engineering, modeling the displacement flow inside a casing or drill string for cementing operations has received less attention. Although predicting displacement efficiency inside a full-length pipe is desired by cementing engineers, the attempt of developing a model with both efficiency and accuracy faces challenges. Access to computer simulators for this purpose is limited. Compared with annular flow, the displacement flow inside pipe, although within a simpler geometry and without eccentricity effect, is not simpler in physics, modelling strategy and predictability, because a variety of flow patterns and flow instabilities can develop to create complicated fluid interfaces. In this paper, we present an integrated numerical model developed to simulate displacement flows inside a full-length pipe, which connects an existing annulus model to enable complete displacement simulations of cementing jobs. The model uses three-dimensional grid to solve fluid concentrations with degrees of mixing, and incorporates flow instability detection and flow regime determination. Applied in cementing, the model accounts for effects of pumping rate, well inclination, pipe rotation, fluid densities, rheological parameters and more. This computationally efficient model does not rely on high-resolution mesh as often required by conventional Computational Fluid Dynamics models, thus it is suitable to be implemented in a cementing software for daily use by well cementing engineers. The methodology of the model is discussed in detail in this paper. To validate the model, we examine simulation results against experimental results obtained in our laboratory tests and CFD simulations; acceptable agreement is found under different testing conditions. We also presented two case studies of real cementing jobs with cement evaluation logs compared to simulation results, showing that the model can predict consistent displacement efficiency results.

The selection of an apt technology for the treatment of Oilfield Produced Water (OFPW) depends mainly on the quality of OFPW and methods of pre-and post-treatment processes. The most challenging part of the OFPW treatment process is the removal of Suspended Solid (SS), Oil & Grease (O&G) and dissolved organics. SS and O&G pose an acute problem to the membrane filtration system by fouling the membrane surface which increases operation & maintenance costs and decreases the life of the membrane. Fouling of the membrane surface is mainly attributed to the presence of low molecular weight aromatic compounds and naphthenic acids in the suspended and dissolved organic compounds. Thus, the removal of these suspended and dissolved organic compounds before membrane filtration proffers a challenge to the researchers. In this research, bioremediation process has been applied to remove the organic compounds and the performance and fouling behaviour of hollow fibre Microfiltration (MF), Ultrafiltration (UF) and Nanofiltration (NF) membranes after the bioremediation process has been analyzed in detail. The level of toxicity was determined by comparing the pollutants with the safe discharge limit for disposal into the environment set by Central Pollution Control Board (CPCB), India. The research presents its novelty by using a hydrocarbon-degrading bacteria, Pseudomonas aeruginosa for the Reduction of Organic Loads (ROL) from OFPW of Moran oil field of Upper Assam as a pre-treatment to membrane filtration. The Total Sum Corrected Area (TSCA) method through chromatographic analyses was used for this. The organic loads removal from OFPW by the TSCA method was found to be 67–100%, 100% and 100% after 7, 14 and 21 days of bioremediation respectively. The major parameters in feed OFPW of Moran oil field were found to be pH (7.5–9.3), Total Dissolved Solid (TDS) (1.79–4.75) ppt, O&G (1.78–2.8) ppt, Salinity (2.94–6.98) ppt, Chloride (Cl⁻) (1.6–3.86) ppt, Bicarbonate (HCO₃⁻) (2.89–4.03) ppt. It was observed that the ranges of pollutants removal by NF was highest such as TDS (26–86%), salinity (81–86%), turbidity (78–94%), hardness (67–75%), O&G (96–99%), Cl⁻ (80–89%) and HCO₃⁻ (95–97%).

This paper presents the study of the effect of multiple ultrasonic impacts on submicron asphaltene aggregates in a toluene/heptane solution, conducted with dynamic light scattering technique. The objects of the study were four samples of asphaltenes obtained from four different oils. For all samples, the change in the average size of the asphaltene submicron aggregates with time was measured after the addition of a precipitant (heptane) to a solution of asphaltenes in toluene at an amount above the threshold concentration. Asphaltene aggregates formed in solution after the addition of the precipitant and were subjected to ultrasonic treatment, which led to the destruction of the asphaltene aggregates. Aggregation of destroyed asphaltenes was observed. The kinetics of this aggregation were similar to the kinetics of aggregation of asphaltenes after the addition of a precipitant. Multiple iterations of asphaltene aggregate destruction in the sample led to a significant change in the kinetics of aggregation: the growth of aggregates slowed and stabilized at a size of approximately 200 nm and 30 nm for the different studied samples.

The Mishrif Formation (Cenomanian -E Turonian) is one of the most important geological formations in the Middle East and Iraq because it contains enormous petroleum accumulations. It is considered to be the first reservoir in the region, and is still being studied because of its economic significance. The carbonate of the Mishrif Formation derives from a variety of depositional settings, including mid-ramp, shoal, lagoon, and intertidal. The five main microfacies discussed in this paper are wackestone, packstone, grainstone, floatstone, and bindstone. The most frequent fossilised components found in the Mishrif Formation are rudists, benthic foraminifera, echinoderms, burrows molluscs, and algae. According to the microfacies and analysed wireline log data, the sequence stratigraphy of the studied formation is composed of two regression cycles. Five parasequences of transgressive–regressive cycles make up the depositional sequence of the Mishrif Formation. The standard depositional environments seem to demonstrate a gradual regression, beginning with a short period of the outer ramp, then a steady period of the mid-ramp, and ending in the intertidal environment. Additionally, the study recorded two regional maximum flooding surfaces: K-135 and K-140. The former is present in the lowermost part of the formation, while the other lies in the middle. This study shows a close relationship between facies (environments) and hydrocarbon accumulation. The increased accumulation focuses on the lower part of the studied formation, and seems to be lower in the upper part of the formation as a result of changes in the environment of deposition.

Water flooding and pressure maintenance are recommended to improve oil recovery practices after low recovery of petroleum reservoirs occurs during primary production. Salt crystal formation is a frequent occurrence when using these techniques. Several experimental, numerical, and theoretical studies have been done on the mechanisms underlying scaling and permeability reduction in porous media; however, there has not been a satisfactory model developed. This study developed a phenomenological model to predict formation damage caused by salt deposition. Compared with existing models, which provide a scaling tendency, the proposed model predicts the profile of scale deposition. The salt precipitation model simulates reactive fluid flow through porous media. A thermodynamic, kinetic, and flow hydrodynamic model was developed and coupled with the ion transport equation to describe the movement of ions. Further, a set of carefully designed dynamic experiments were conducted and the data were compared with the model predictions. Model forecasts and experimental data were observed to have an average absolute error (AAE) ranging from 0.68% to 5.94%, which indicates the model's suitability.

The intensive use of petroleum hydrocarbon products has made them priority environmental pollutants. When petroleum hydrocarbons enter the soil, a change in physical, chemical, and biological properties is observed. The natural restoration of oil-contaminated soils is a lengthy process; therefore, remediation is often required. The aim of this study is to assess the change in the ecological state of haplic chernozem soil contaminated with oil, fuel oil, and gasoline after remediation. The indicators of soil biological activity, such as phytotoxicity (germination, length of shoots and roots), the activity of oxidoreductase enzymes (catalase and dehydrogenases), and the total number of bacteria were studied. The effects of nitroammophoska fertilizer, sodium humate, biochar, and the biofertilizer “Baikal EM-1” on the ecological state of soils contaminated with oil, fuel oil, and gasoline were studied. Pollution with oil, fuel oil, and gasoline decreased the values of all biological indicators. The most sensitive indicator was the length of radish roots in soils polluted with oil, gasoline, and fuel oil after remediation with nitroammophoska and Baikal EM-1 addition. The length of roots was the most sensitive indicator when remediation was performed with biochar and sodium humate added to soil contaminated with oil and gasoline, and with contamination of haplic chernozem soil with fuel oil, the total number of bacteria was the most sensitive indicator. The most effective ameliorant to phytotoxicity indicators for oil pollution was a 1 D dose of biochar, for fuel oil it was 1 D biochar and 2 D sodium humate, and for gasoline it was a 2 D dose of biochar and Baikal EM-1. All ameliorants at most of the studied doses increased dehydrogenase activity, but increased catalase activity only in some cases. An increase in the total number of bacteria in oil-contaminated soils was promoted by biochar and nitroammophoska at a dose of 2 D. Nitroammophoska was the most effective in ameliorant in soils contaminated with fuel oil; in soils polluted with gasoline, all doses of ameliorant increased the number of bacteria equally. The stimulating effect of ameliorants on biological activity of oil-contaminated haplic chernozem were in the following sequence: nitroammophoska > biochar > sodium humate > Baikal EM-1. The 2 D biochar dose was most effective. The stimulation of biological indicators by ameliorants when soil was contaminated with fuel oil were in the following sequence: biochar > Baikal EM-1 > sodium humate > nitroammophoska. The same sequence of ameliorant stimulation was observed in soil polluted with gasoline. The results of this study can be used to biodiagnose the ecological state of oil-contaminated soils after remediation.

Modeling the environmental sensitivity index (ESI) is vital in the planning and management processes, especially along the coastal areas. The main objectives of the study were to define the main sources of polycyclic aromatic hydrocarbons (PAHs), establish an ESI model, and measure the risk of PAHs on humans and the environment using various equations. The methodology of the research involved analyzing PAHs according to the EPA 550 methodology in sediments of the coastline in two important coastline areas in Egypt, namely the Gulf of Suez and the Mediterranean Sea, modeling the sensitivity of PAHs using ArcGIS 10.5 by integrating different physical, biological, and land use/cover factors, identifying the sources, and performing a risk assessment. Nine sediment samples were collected from each area. The produced sensitivity map could explain the highly sensitive areas along the Mediterranean Sea and Gulf of Suez coastlines (especially areas that were near drains' outlets, industrial sites, and sea ports). The highest mean PAH concentrations were Acenaphthylene and Fluorine in the Mediterranean Sea and Suez Gulf, respectively. It's obvious that the individual PAH concentrations were within the ERL, ERM, and PEL threshold limits, indicating no adverse biological impacts. The ratios of BaA/BaA + Chy, Flu/Flu + Py, and Ant/Ant + Phe gave an indication that most PAH sources were petrogenic (63.64%) and others (36.36%) were from petroleum combustion. The principle component analysis (PCA) indicated a diverse correlation among the isomer ratios and LU/LC activities. The carcinogenic risk values were in the very low category (<10⁻⁶) for both children and adults. The most significant contributors to carcinogenicity were IP and BkFlu in the Mediterranean Sea and Suez Gulf, respectively. Increasing sources of carbon in seawater, especially with climatic change, may impact the aquatic environment and have impacts on organisms and coral reefs. So it is highly recommended to keep shorelines and seawater free of oil spillage activities along the coastal areas or take actions towards this.

Carbon dioxide flooding is of interest due to its high oil-sweep efficiency for enhanced oil recovery and contribution to the reduction of greenhouse gas emissions. However, when CO₂ is injected into deep geological strata, asphaltene may precipitate. In this work, the effect of Al₂O₃ nanoparticles on the deposition of asphaltene was examined by assessing the variations of bond number and interfacial tension at different pressures and a temperature of 60 °C. The asphaltene onset point and intensity were characterized using the bond number, which proved a better indicator of changes in oil droplet shape and interfacial tension with gravity. Synthesized mixtures of toluene and n-heptane that contained two different kinds of asphaltenes were used as M and D oil samples. A 0.06 mass% addition of Al₂O₃ nanoparticles, which worked best for reduction of interfacial tension, was also applied at various pressures. Addition of nanoparticles to the oils prevented asphaltene precipitation in both synthetic samples by altering the slope of the plot of interfacial tension with pressure by 49.7% for the M sample and 9.0% for the D sample. The Al₂O₃ nanoparticles were found to be more effective at inhibiting asphaltene precipitation for the M oil sample due to its lower H/C ratio and higher nitrogen content.

The Upper Cretaceous carbonate successions of the Sarvak Formation host giant oil reservoirs in the Persian Gulf. In this research, a total of 28 oil samples from nine oilfields located in the western, central and eastern parts of the Persian Gulf region were studied to determine the genetic relationships of oils, depositional setting of possible source rocks, thermal maturity, and source-rock ages in the Persian Gulf basin. According to the measured geochemical data, the source rocks facies vary from marine carbonates and marl/carbonates in the central and eastern oilfields to shale/carbonates in the western oilfields. The Pr/Ph ratio, steranes and terpanes suggest anoxic to dysoxic conditions of the depositional environments. The depositional environments experienced both low water stratification/low salinity and normal salinity/unstratified conditions. Evaluation of the saturated and aromatic biomarkers shows that all oil samples are mature and most of the source rocks lie within the beginning of the oil-generation window. The thermal maturity of the central oilfields is higher than that of the other samples, and has gone beyond the oil-generation stage. The C₂₈/C₂₉ steranes ratio suggest that the central oilfields of the Persian Gulf have Paleozoic and Jurassic source rocks, whereas the Sarvak reservoir in other parts of this region is sourced from Cretaceous carbonate rocks.

The objective of this experimental study is to improve the cementing bond quality of sandstone oil-gas well along the wellbore cement-formation interface (WCFI), so as to ensure long-term zonal isolation throughout the lifecycle of the well by using NSO solution as filtercake modifier which was developed in the laboratory. According to designed experimental method and API RP 10, the effectiveness of filtercake modifier (NSO) on the bonding strength at the WCFI was assessed by using designed simulated wellbore as sandstone formation. The experimental results indicated that the samples which were treated with NSO solution had higher bond strength over untreated samples. The strength generally increased with curing period as for treated samples, 0.198, 0.374, 0.433 and 0.473 MPa for 3, 7, 15, and 30 days respectively while for the untreated samples the bond strength were 0.050, 0.070, 0.81 and 0.100 MPa for the same period. The water-based filtercake modification techniques had significantly enhanced the bonding strength of WCFI by increasing rates above 296%. Improvement of bond strength to the treated sample was due to filtercake modification as a result of formation of cementitious material as revealed in FTIR spectral such as Calcium-Silicate-Hydrate (C–S–H) and other geopolymers like Calcium-Aluminium-Silicate-Hydrate (C-A-S-H) and Sodium-Aluminium-Silicate-Hydrate (N-A-S-H)) along the interface which filled the existed pores hence reducing porosity hence high strength of bond. The low transmittance value for the NSO treated samples revealed that there were more cementitious materials existing at the WCFI which led to improvement of bonding strength as compared to the untreated samples. The lower/poor bond strength for the untreated samples is due to existence of untreated, thick water-based filtercake films at WCFI, which prevented the complete hydration process between rock grains and cement slurry components to make chemical binder of cement slurry material and formation.