Modern Oil and Gas Production from Ocean Depths to Delivered Energy
Modern Oil and Gas Production from Ocean Depths to Delivered Energy
Blog Article
The oceans cover over 70% of the Earth. This is the 180th Meridian. From orbit, almost no land is visible, making the hemisphere seem a giant ocean. Yet the planet is called Earth, not Water. Since ancient times, it has been known there is solid ground underwater: the ocean bottom, and even deeper, there is something people have long been extracting—precious stones, metals, raw chemicals, hydrocarbons. This means that as onshore mineral resources are depleted, people must dive deep into shelf waters. Engineers call it open underwater mining of shelf deposits.
At first, this was possible only in shallow water, but with each decade, people are going deeper and deeper. This process is underway. Oil is extracted on the shelf of the Pachora Sea—this Arctic oil is the northernmost in the world. Hydrocarbons are sourced from the Baltic and Caspian seas, and several offshore platforms operate near Sakhalin, including the first stationary gas platform in Russia and oil platforms Buun Ossk and Pelon Aaya B. Work is conducted 24/7, year-round, pushing the limits of science and technology. Oil and gas are extracted to the surface and transported to the mainland for processing and further use. That is how the seabed is developed by extracting power from the water's depths.
Offshore platforms like Luna A or Lon A for short are more often reached by air rather than by sea. Boarding a helicopter requires completion of specialized helicopter underwater escape training, as takeoff and landing are considered dangerous. The platform itself is a full-fledged mini city. After a week, it is still possible to lose one's way around its tangled corridors, stairs, levels, and rooms. This colossus may be generally divided into two large areas: production and accommodation. The first area has everything for hydrocarbon production and platform operation; the second offers everything for comfortable living—cabins, leisure, meals, fast internet. It seems like a hotel on the mainland rather than a reinforced concrete tech island in the open sea.
On a sunny day, it may seem like a stone's throw from shore, but this is misleading. In fact, it is 14 km to the Sakhalin shore, and the distance from the platform's highest point to the seabed is 152 m—higher than the Great Pyramid, higher than Europe's tallest Ferris wheel, and just a bit shorter than the Shov Tower in Moscow. Particular interest is stirred by the platform supports, or gravity-based structures. These are gigantic structures resting on the seabed, designed to withstand both the weight of the platform and the pressure of pack ice in winter, and even potential seismic loads. Each support is also a structure with internal spaces and communications.
For example, the first support has seawater pumps to desalinate water for further use on the platform. The third support has the main export pipelines for transporting gas to Sakhalin. The fourth one has the embedded sewage system, and the second support has wells for hydrocarbon production. In total, there are some 24 wells, each with a depth between 2,000 and 3,000 m. The Lon field is not a single large cavity but an area of scattered finely porous rocks like sandstone. Thus, wells are drilled down and in different directions to maximize gas extraction area, with some wells extending as far as 9 km away from the Lunco A platform.
High-Tech Drilling and Well Architecture
How are multiple holes made in the ground if the platform itself is stationary? The answer: the drilling rig is mobile. It can move left, right, forwards, and back within a rectangle, and mapped onto a circle, this matches the cross-section of one of the gravity supports. Platform drilling is a high-tech process—fully or almost fully automated, with mechanisms operated from a protected operator's cabin.
The production of hydrocarbons is not just about drilling. Gas conditioning for transportation to the mainland is no small task either. The gas underground is a mixture of methane, sand, produced water, and various impurities like condensate. Directing such natural gas to the main export pipelines is strictly forbidden, as pipelines can be damaged quickly if nothing is done, especially concerning produced water in gas.
Gas flow in pipelines is accompanied by fluctuating temperature and pressure, causing water vapor to condense into gas hydrate plugs that clog pipes and stop production. To prevent this, natural gas is conditioned on the platform, for example, by adding monoethylene glycol—an antifreeze agent well known to drivers. Monoethylene glycol prevents water in natural gas from freezing, thus stopping hydrate formation. After this, the natural gas is ready to leave the platform through pipes on the seabed, heading to Sakhalin.
For a deeper look at advanced offshore drilling automation, Drilling Simulators provide invaluable digital training and operational insight for this high-tech process.
Onshore Processing and Resource Separation
Having reached Sakhalin, gas is subject to multi-step drying and separation processes at the onshore processing facility (OPF). The facility, built in just four years on wild, undeveloped terrain, is now a city-like industrial complex. Gas and oil leave platforms and reach the mainland almost unchanged. Gas from the Luna A platform contains ethylene glycol, produced water, condensate, and a blend of liquid hydrocarbons, while crude oil from northern offshore platforms contains associated gas.
The OPF separates these components. The first separator, a three-phaser, divides natural gas into methane, condensate, and water with ethylene glycol. Nothing is dumped or discarded; the OPF is eco-friendly and interconnected with all facilities in the chain of production, conditioning, and transportation of hydrocarbons. The facility even generates electricity by burning natural gas produced on the platform, with enough energy to operate the facility and the offshore platform. Electricity flows back along an underground cable to Luna A.
The operations diagram of the OPF complex shows ethylene glycol is dewatered and returned to the platform for reuse, condensate is blended with oil, and purified natural gas is fed into a separate pipeline. This is how the whole system works.