Iraqi Journal of Oil and Gas Research

Horizontal wells with multiple completion parts have become a common completion technique in the oil and gas industry. Sand and asphalt production problems, damaged zones and water cresting or gas coning are the main reasons for using this technique to sustain or improve oil and gas recovery. However, using such completion technique introduces negative effects on pressure behavior of horizontal wells. This paper introduces new mathematical models for horizontal well containing several closed completed sections acting in finite and infinite reservoirs. These models can be used to evaluate the impact of the completion techniques on both pressure behaviors and flow regimes either in the vicinity of wellbore or at the outer boundary of reservoirs. They can be used also to investigate the change in productivity index that would result due to the usage of certain type of completion technique. In this research, the completed sections (cemented or isolated parts) and the places where packers are installed are considered as no-flow sections. These sections are expected to increase pressure drop required for flowing reservoir fluid toward wellbore. They are also expected to change flow regimes mainly in the vicinity of wellbore. Several models have been developed and solved in this study for different completion techniques, wellbore conditions and reservoir configuration. It has been found that the great impact of completion techniques is observed on flow regimes that commonly develop in the drainage area close to wellbore.This impact shows similar trends to the skin factor. Several new flow regimes have been observed

Most of the oil fields inject water as a secondary recovery to maintain the pressure at the reservoir when reservoir natural energy is consumed and pressure is declined during the initial production stage. The disadvantage of using water as injection fluid is that the injected water will tend to finger by the oil because of low viscosity of water compared to oil and moves through the shortest path to the production wells under high water-oil mobility ratio condition, so large amounts of oil are left behind. In order to avoid the high mobility condition of injected water, polymers have been used. It is simply a chemicals dissolved in the injected water and because of the polymer high molecular weight, small amount within several hundred ppm will give significant increase in viscosity of injected water. As a result, it leads to better mobility ratio, reduces fingering effect and increases sweep efficiency. The scope of the current work is to study the effect of polymer injection in porous media on water cut and oil recovery and compare the results with that of water flooding. This study has been done using artificial core with a permeability of 1.82 Darcy and porosity ranging from 32.7 % to 33.7%. Three types of polymers with different molecular weight have been used. Results from artificial core flood experiments show that polymers reduce water cut and improve oil recovery.

Tertiary Formation is divided into three main reservoir units. They are designated from top to bottom designated as Jeribe, Dhiban, and Euphrates. Jeribe unit is the main producing layer in the Tertiary Formation. Formation evaluation has been carried out for the Tertiary Formation of the Ajeel Field by analyzing various log and core data giving a full description of the properties in this Formation. Didger software package 3 was used to digitize the available log data, with the log interpretation by Interactive Petrophysics (IP V3.5) software which was used to correct the environmental parameters and produce the results of CPI. The logs studied were (caliper, deep resistivity, shallow resistivity, gamma ray, sonic porosity, neutron porosity and bulk density). Pickett method was used to determine of the Archie's parameters (the tortuosity factor (a), cementation exponent (m) and the saturation exponent (n)). Total porosity was also calculated using neutron-density porosity logs. The effective porosity was obtained from the total one after extracting the shale percentages from the formation. classical method were used to predicate permeability with the core permeability shows the method correlations. These correlations were used to estimate permeability in uncored wells. According to these work, Tertiary Formation was divided into seven zones (Jeribe in to J1, J2, J3 and Dhiban in to D1, D2 and Euphrates in to E1, E2).

Knowledge of the properties of reservoir fluids are very important in petroleum reservoir engineering (e.g. estimation of reserves in an oil reservoir, well test inflow performance calculations, and numerical reservoir simulation). The process of obtaining accurate values for these physical properties for hydrocarbon is most important in different oil industries. The main resource to get these properties is laboratory measurements but in many cases these measurements not available, thus other methods can be used to estimate these properties. This paper concerns with the prediction of the phase behavior and physical properties for a Middle Eastern sandstone reservoir by using multiphase equilibrium and properties determination program. Soave-Redlich-Kwong Equation of State & Peng-Robinson’s Equation of State and its modifications have been used to calculate the physical properties of reservoir fluid. To do so, each laboratory experiment was first simulated with the cubic Peng Robinson EOS without performing any regression and compared to the laboratory observations (PVT) as primarily results. Then splitting and lumping processes were used to tune or characterize the EOS so that it can reproduce the PVT experiments. The calculated PVT properties from these two steps are compared with the measured PVT data and the results show that the splitting and lumping processes given a good accuracy in predicting the PVT properties of the sandstone reservoir.

In this work, microwave (MW) plasma reactor was used for dry reforming of methane (DRM) reaction to produce syngas (H2 and CO). The Box-Behnken algorithm based on the response surface methodology (RSM) was utilized to optimize plasma DRM process. The effects of process variables including MW power, CO2/CH4 ratio and total feed flow rate on produced syngas selectivities and syngas ratio (H2/CO) were studied by the Analysis of variance (ANOVA) method using three different models based on quadratic polynomial regression. Both experimental and optimized results confirmed the important paramount role of MW power on syngas selectivity compared to other investigated parameters. The CO selectivity and H2/CO ratio was considerably influenced by CO2/CH4 ratio while the effects of total feed flowrate on plasma DRM performance was insignificant. The interactions between the different variables had a weak effect on the H2 selectivity and ratio of H2/CO. At the maximum desirable value of 0.95, the optimum H2 and CO selectivities were 53.57% and 57.35 % with a H2/CO ratio of 0.9.

It’s well known that raw oil deposits would cause various health impacts particularly upon those occupationally exposed workers ranging from mild to lethal health influences. This study therefore was designed to probability of finding any prior health symptoms that may act as early indicators of such sever health syndromes which can assist in prediction and expectation of such problems well before being occurred. A total of 50 workers from Al-Dora oil refinery and 10 individuals from well away sites to act as control samples were subjected to this study. All samples were interviewed individually using personal questionnaire, and subsequently examined for total blood content vanadium. Further examination, consisting clinical blood test, was carried out. The current study has found that most occupationally exposed workers suffering various physiological syndromes such as digestive, dermal, and respiratory dieses. Furthermore, it was found several health symptoms such as hair fallen, teeth decay, vision impairment and weight fluctuation, in addition to other clinical symptoms relating to blood components such as packed cell volume (PCV), lymphocytes and eosinophile (WBC) since all these variables have been found significantly (P≥ 0.05) regarding exposure period, blood vanadium content and the number of health troubles that workers displayed and insignificantly (P≥ 0.05) in case of the worker age. Also, it has been found that the most examined workers were suffering from psychological problems such as depression, stress and malaise.

Asphaltene precipitation from reservoir fluids during oil production is a serious problem because it can result in plugging of the formation, wellbores and production facilities. An efficient modelling technique based on the representation of the precipitated asphaltene from live oil of Khasib Formation / Halfaya Oil Field as a pure dense phase is presented. The success of the approach is based on the division of the heaviest component in the oil into a nonprecipitating and a precipitating component. This case study described the procedure for modeling the precipitation of asphaltene from a live reservoir oil due to pressure depletion. The thermodynamic model used to describe the precipitation of asphaltene. The precipitation of asphaltene is modelled using a multiphase flash calculation in which the fluid phases are described with an equation of state (Peng-Robinson equation of state) and the fugacities of components in the solid phase are predicted using the solid model. The used model showed that there was asphaltene precipitation problem of the selected fluid at specified conditions and approaching these conditions should be avoided during production to provide treatment costs.