Researcher Ahmed Hatif Karim's doctoral dissertation was discussed at the College of Engineering, Department of Mechanical Engineering, University of Basra, entitled Numerical and Experimental Analysis Two-Phase Flow in Oil Horizontal wellbore

Global oil reserves are rapidly depleting. This has led to a shift in focus toward regions that are more difficult to access. In highly permeable reservoirs, low pressure drawdown regions show strong influence of perforation density distribution along horizontal wells on oil production. One of the most important issues in production engineering is the two-phase flow behavior. For horizontal wells, two-phase flow offers several flow patterns depending upon the specific flow rates of each phase. The drilling of horizontal wells has increased in recent years due to greater productivity compared to vertical wells. The flow in horizontal perforated wells is more complicated than in horizontal pipes due to higher friction factor inflow from perforations. Furthermore, the velocity profile in the wellbore alters from mixing with the radial flow from perforations. As such, pressure gradient along the wellbore is altered. This study seeks to investigate two-phase flow within horizontal perforated wellbore. More specifically, it looks into the fundamental aspects of two-phase flow, which entail the flow patterns (bubble flow (BF), slug flow (SF), stratified flow (STRAF), wave flow (WAF) and annular flow (ANNF)), total pressure along the perforated horizontal wellbore (TPD) (which encompasses the friction pressure along the perforated horizontal wellbore, acceleration pressure along the perforated horizontal wellbore, and mixing pressure along the perforated horizontal wellbore), void fraction (VF) and productivity along the horizontal wellbore at varying  velocities of both axial (AXF) and radial flow (RDF). The current work includes a numerical and experimental investigation on air-water flow in the horizontal perforated wellbore for two models. The bore consists of a length of 3m and an inner diameter of 25.4mm, the first model has eighteen perforations while the second model has nine perforations which are distributed within the horizontal wellbore with perforation phase 180 degrees and diameter (4) mm, to simulate flow in a horizontal wellbore. Air enters the perforations as radial flow and the water enters through the mainstream as axial flow. For the numerical study, the ANSYS FLUENT has been employed to address the problem of unsteady, incompressible, turbulent, three-dimensional flow using the Volume of Fluid (VOF) model. During the experimental study, based on the calculated static pressure along the perforated horizontal wellbore and flow pattern observations, the experimental device was constructed accordingly. The dimensions of the test pipe for both the experiment and the numerical simulation are identical. With respect to the wellbore land configuration, it is noted that productivity is consistently higher in a perforated horizontal wellbore compared to a smooth, unperforated one. As the water  flow rate was kept constant, the (TPD),  velocity of mixture, and (VF) increased with air  velocity. When the air  velocity rises, the liquid film thickness decreases, while the (PD) increases with an increase in the (Rem). Liquid and air products both increase with perforation distribution in the second model and decrease with the first model of the perforated horizontal wellbore. It was observed that with an increase in the air flow rate the air product also increases. The radial flow increases the liquid product. The optimal product occurred in the annular flow for the second model. The average percentage of the liquid product was 52.93% when the distribution of perforations was 18 in the horizontal wellbore (first model), while increasing the product (liquid) to 60.78% when the distribution of perforations was 9 in the horizontal wellbore. The numerical code utilized in this research has been validated with experimental data and data from other researchers, confirming its dependability. The agreement in results was good through (BF, dispersed bubble flow (DBF), SF, STRAF, WAF, and ANNF) flow behavior in numerical and experimental research. the numerical and experimental data were confirmed and the flow patterns were predicted successfully when compared with the Mandhane map.