Novel Lean Gas Purification Strategy in On-Site Oil Production Fields

In the final stages of oilfield exploitation, associated gas produced alongside oil is processed at gas processing plants (GPPs) to convert it into a commercial product. However, considering the remote locations of oilfields from gas processing facilities and the declining productivity of wells during the late stages of operation, transporting gas over long distances for processing is not economically viable. Consequently, the gas separated during technological processes at the field is either utilized for internal needs or flared. The flaring of gas results in the emission of significant amounts of harmful gases into the environment, making this issue one of the most critical challenges globally. Gas intended for use as fuel must undergo a high level of purification to meet quality standards. Taking these factors into account, an advanced Gas Filter Separator has been developed using innovative technology to purify natural associated gas separated from oil at the field. This system is designed to efficiently remove water, light liquid hydrocarbons, and mechanical impurities. The core concept of the technology is to enhance the efficiency of the separation process within the separator by employing newly designed diffuser-restrictor filters. These specialized filter elements are strategically placed along the inlet line of the separator. When the natural associated gas flows through the restrictor filters, the proximity between the liquid droplets decreases, resulting in their coalescence. This coalescence significantly accelerates the sedimentation of the liquid phase separated from the gas, thereby substantially improving the separation efficiency of the system. The Gas Filter Separator consists of a cylindrical body with a diameter that is 3–4 times larger than the inlet line diameter. The system is equipped with a tangentially connected inlet line attached to the lower side of the body, diffuser-restrictor filters installed inside the inlet line, a manifold where technological lines converge at the inlet, and a device with filter elements mounted on the inlet line and secured with flanges. Additionally, it includes an outlet line connected to the upper side of the body, a specially designed tank located at the bottom of the separator to collect the separated liquid phase, and a drainage line at the base for discharging the accumulated liquid. The diffuser-restrictor filter unit installed on the inlet line is composed of a cylindrical body proportionate to the inlet line diameter. The filter elements feature openings with dimensions equivalent to 1/10 of the inlet line diameter, with the number of openings determined based on the cross-sectional area of the line. These features ensure efficient separation and purification of the gas. In the technological process, as the gas passes through the diffuser section of the openings in the filter, the flow is directed toward the center of each opening. During this phase, the distance between liquid droplets decreases, leading to their coalescence as they move closer to one another. This process is driven by intermolecular attractive forces within the liquid phase, resulting in the formation of larger droplets. According to Stokes’ law, the increase in droplet size enhances their sedimentation rate within the separator, thereby significantly improving the efficiency of the separation process. The purification of light liquid hydrocarbons (C5+) present in the associated gas separated from oil enables a reduction in oil losses during field production processes. Furthermore, it mitigates the emission of harmful gases into the environment when the gas is utilized as a combustion product, thereby enhancing environmental sustainability and aligning with global efforts to minimize ecological impact.