Processing plants in the oil and gas industry have always had their challenges and seldom been seamlessly smooth. In the following work, an Omani oil field has been selected to apply the best engineering solutions to overcome the difficulties of operating the oil processing plant that fluctuates regularly with variation in oil production volume and fluctuating product quality parameters deviating from the sales agreement. Moreover, it provides optimal surface development facilities to maintain the field productivity with maximum yield. To achieve this goal, theoretical and experimental investigations were carried out through the following three principle steps: (1) Fluid characterization, (2) Pipeline steady state hydraulics, (3) Optimization for the performance of separation process facilities. Fluid analysis tests were performed to identify the fluid composition and their priorities, followed by fluid characterization. A simulation model for the facilities was developed based on experimental data to define the real input properties and operating conditions for the steady-state hydraulics and optimization task. HYSYS simulation software was used for determining fluid characterization to match between PVT lab analysis and simulations models. PipeSim software was used for steady hydraulics for a new 25km pipeline for optimum design and operating parameters. Different sizes of pipeline diameters (6", 8" and 10") with various materials of construction (C.S., CS+HDPE, GRE, and CS+SS Clad) were evaluated considering technical and cost aspects. 10-inch CS+HDPE (Carbon Steel with High-Density Polyethylene liner) pipeline was recommended to transport the multi-phase production from the field wells to central processing facilities. Flow assurance issues such as hydrate, wax, erosion, backpressure, and liquid holdup were identified, and an appropriate solution to overcome these issues during pipeline operation was specified. It is advisable to run a pipeline cleaning operation using a pig or install a single-stage multi-phase pump at the end of field life to overcoming the backpressure created from high liquid hold up due to a fraction of the element pipe occupied by the liquid at the same instant. Moreover, the oil processing facilities have been optimized based on the number of selected separation stages and operating pressure to maximize the oil production and gas separation at the first stage and avoid gas losses at downstream facilities. As a result, one separation stage with an atmospheric crude oil storage tank has been selected as an optimal process configuration for oil production facilities with an operating pressure of 5 bar at the inlet separator unit.