Where do oil and gas come from and where do they go? This is how a drop of oil begins its "wonderful journey"

The oil and gas come from underground to the wellhead. They look left and right, rub their sleepy eyes and ask: "Where is this? Where should I go?" Haha, we all know that it will go through a wonderful journey and eventually "walk" into the lives of each of us.

We know that most oil and gas fields are located in mountains, grasslands, Gobi, deserts and unfathomable seabeds. For oil and gas to be used by people, they still need to travel a long distance. However, before the journey, people need to "dress up" and then start the journey "beautifully". Usually, they need to "walk" a few thousand meters or tens of kilometers at least, or hundreds of kilometers or thousands of kilometers at most. They even need to climb mountains and cross rivers, lakes and seas, and cross vast deserts and Gobi. So, how do oil and natural gas "walk" into people's lives?

Crude oil, natural gas and other oil and gas mixtures need to arrive at the "gathering and transportation dressing room" before participating in the long-distance journey of pipeline transportation. After being processed and processed here, they can become a qualified crude oil and natural gas "traveler" after "dressing up". There are generally three paths from the wellhead to the "gathering and transportation dressing room", which we can call the "first-level and a half (or first-level), second-level, and third-level station" gathering and transportation process. Although the paths are different, the "traveling method" is the same, mainly using a closed transportation method. The oil and gas medium is isolated from the atmosphere during the entire process, and this stage of the journey is completed in a closed pipeline.

After the oil and gas arrive at the "gathering and transportation dressing room", they need to complete the "dressing up" in terms of oil and gas metering, crude oil dehydration, oil and gas separation, natural gas purification, crude oil stabilization, and sewage recovery. Oil and gas metering is the measurement of oil and natural gas flow, that is, the amount of oil and gas needs to be counted before departure. There are two ways to count: one is to count the amount of oil and gas that just emerged from the underground well, so that we can clearly understand the dynamic changes of the underground oil well; the other is to count the amount of oil and gas that has been boarded on the pipeline and is ready to start a long journey after the oil and gas is "carefully dressed up". This is also to tell the staff at the end of the journey how many tourists are on this journey, which is convenient for handover management.

The crude oil that comes up from underground with a huff and puff carries many "small beads of sweat" on it. The "small beads of sweat" will slow down the crude oil, which will not only make the long-distance journey more tiring, but also increase the energy consumption of pipeline transportation. Therefore, crude oil dehydration is an important step in "dressing up". There are many methods for crude oil dehydration, mainly sedimentation dehydration, centrifugal dehydration, filtration dehydration, electrochemical combined dehydration, etc. Of course, crude oil dehydration also requires a specific "shower gel" - demulsifier, which can help crude oil get rid of the "small beads of sweat" on its body and make itself more refreshed.

Crude oil shakes off the "little sweat beads" on its body - water, but it also has a "little follower" - natural gas. So before starting a long journey, oil and gas must be separated. Crude oil and natural gas go to the oil and gas separator together. After passing through the oil and gas stabilization device, the oil and gas are separated. At this time, the crude oil is relaxed, meets the requirements of long-distance travel, and becomes a qualified crude oil traveler.

In fact, the natural gas that comes up from underground has small beads of sweat on it, just like crude oil. If the small beads of sweat continue to travel with the natural gas, a substance called "natural gas hydrate" will be produced, which will not only make the natural gas travel difficult, but even cause "traffic jams" in the pipeline. Therefore, only when the number of "small water droplets" carried by natural gas meets the requirements of long-distance travel can it become a qualified natural gas traveler. There are four main methods for dehydrating natural gas: cooling dehydration, absorption dehydration, adsorption dehydration and membrane separation dehydration.

After talking about oil and gas on the ground, let’s talk about how oil and gas travel under the sea.

The ocean occupies about 70% of the earth's surface. It not only breeds a variety of life, but also contains rich resources. Marine oil and gas, as an important marine resource, accounts for one-third of the world's total oil and gas resources. China is a maritime power with rich oil and gas resources in the Bohai Sea, the East China Sea and the South China Sea. These resources flowing in the seabed rocks are being developed continuously. The production of offshore oil and gas fields is the process of extracting crude oil or natural gas from the seabed oil (gas) reservoirs, collecting, initially separating and processing oil, gas and water, and storing and shipping them for a short period of time or transporting them through sea pipelines. The processing of offshore oil and gas is mainly carried out in offshore oil and gas processing plants (FPSOs), which are one of the largest offshore steel giants on the planet. The huge body made of steel like seven Eiffel Towers can easily dock the super-large hulls of three Boeing 747s and process up to 30,000 tons of crude oil per day. It can process the mixture of oil, gas and water from the seabed oil wells into qualified crude oil and natural gas. After the oil and gas reach a certain storage volume, they are transported to the land by shuttle tankers through the crude oil export system. CNOOC currently owns 17 such offshore steel giants, making it one of the oil companies with the most FPSOs in the world.

Whether it is terrestrial oil and gas or marine oil and gas, after careful "dressing up", the natural gas "sister" and crude oil "little brother" encouraged each other, and after a long journey and crossing mountains and rivers, they arrived at their beautiful "new home".

my country has built many oil and gas lifeline pipeline projects, such as the West-East Gas Pipeline Project, a landmark construction project that kicked off the "Western Development". This is my country's longest and largest-diameter gas pipeline. The natural gas baby starts from the Lunnan Oil and Gas Field in the Tarim Basin in Xinjiang, and goes all the way east, passing through nine provinces and regions including Xinjiang, Gansu, Ningxia, Shaanxi, Shanxi, Henan, Anhui, Jiangsu, and Shanghai. It travels 8,000 miles under the clouds and moon before reaching its destination in Shanghai.

The natural gas from the Sichuan-East Gas Pipeline Project starts from Puguang in northeastern Sichuan, passes through Sichuan, Chongqing, Hubei, Anhui, and Zhejiang, and finally arrives in Shanghai. The establishment of the Sichuan-East Gas Pipeline Project has made it possible for Sichuan's natural gas to be transported out of Sichuan. At the same time, the natural gas arriving in Shanghai has brought great help to the energy security and economic development of the Yangtze River Basin and the Yangtze River Delta region.

Natural gas babies can not only "travel" domestically, but also travel abroad. For example, the China-Russia East Line Natural Gas Pipeline, which was jointly built by China National Petroleum Corporation and Gazprom, starts from Eastern Siberia, Russia, and enters Heihe City, Heilongjiang Province, China from Blagoveshchensk, with a total length of 8,000 kilometers; in addition, refined oil can also be transported in multiple batches of different oil products in the same pipeline.

The Lanzhou-Chengdu-Chongqing refined oil pipeline, which was completed in September 2002, starts in Lanzhou and ends in Chongqing. It is about 1,250 kilometers long and is China's first large-caliber, high-pressure, long-distance refined oil pipeline. It is known as the "energy artery" of the northwest and southwest regions and is one of the ten key projects of the western development. Along the way, it passes through the Loess Plateau, Qinba Mountains, Chengdu Plain and Sichuan-Chongqing Hills. The geological and traffic conditions in many sections are extremely bad. The refined oil "little brother" overcame many difficulties and arrived at his new home - Chengdu and Chongqing.

When oil and natural gas are transported in pipelines, a force is needed to push them forward, and this force is called "pressure". During the long journey of oil and gas, if the "pressure" is not enough for a long time, they can't move. But many people are looking forward to their arrival, but they are not allowed to rest. What should we do? Don't worry, two magic weapons are needed to solve this problem - pumps and compressors. They are like "little hearts" distributed on the pipelines, beating strongly and continuously, providing energy for the oil and gas, ensuring that they "do not strike" and arrive at the destination smoothly to complete their mission.

When we think of the mysterious underwater world, fish and corals, algae and pearls, shipwrecks and treasures immediately come to mind. However, in such a vast space, there are also "links" that stretch thousands or even tens of thousands of kilometers under the sea, connecting the land under our feet. They are submarine pipelines.

Nord Stream Pipeline is currently the longest submarine natural gas pipeline in the world. It starts from the port of Vyborg in Russia, crosses the Baltic Sea, and lands in Germany, with a total length of 1,222 kilometers. The difference from the construction of onshore pipelines is that we cannot transform the topography of the seabed, so there are difficulties everywhere in the design and construction process. So how to lay submarine pipelines? We can transport the pipes to the pipe-laying ship through the pipe transport ship, and then make the pipe section interface on the pipe-laying ship. After the connection is completed, it will be sent to the underwater pipe laying site along the slide, pipe bracket and other devices on the pipe-laying ship.

After a long journey, oil and gas partners may stay in their homes for a while before entering thousands of households. We can call this home a "gas storage" or "oil depot". An underground gas storage is an artificial gas reservoir formed by injecting natural gas into underground space. To make a simple analogy, an underground gas storage is like an oversized natural gas "warehouse". Natural gas is re-injected when gas is less used, and gas is extracted during peak gas usage. The depth of an underground gas storage is generally 2,000 to 5,000 meters, with the characteristics of "injection, storage, and extraction". There are four typical types of underground gas storage: depleted oil and gas reservoir gas storage, aquifer gas storage, salt cave gas storage, and cave/abandoned mine/mine type gas storage. Among them, gas reservoir type gas storage is large in number and scale, and has an absolute advantage.

Large gas storage facilities have three functions: seasonal peak load regulation, accident emergency response, and national energy strategic reserve. At present, there are 11 underground gas storage groups in China, with a total of 27 gas storage facilities, with a total working gas volume of more than 20 billion cubic meters, mainly distributed in the Bohai Rim and the eastern region. Hutubi Gas Storage is currently the largest underground gas storage facility in China, and its gas injection and production volume ranks first in the country. Hutubi Gas Storage is the first large-scale supporting system of the West-East Gas Pipeline Network, with a total storage capacity of about 11.7 billion cubic meters.

An oil depot is an independent facility for receiving, sending, storing oil, and producing and processing flammable and combustible liquid products using oil or other materials as raw materials. It is also a base for national oil reserves and supply, used for the accumulation and transfer of oil, and is a link for coordinating crude oil production, crude oil processing, and the supply and transportation of refined oil. There are many types of oil depots, including above-ground oil depots, underground oil depots, semi-underground oil depots, cave oil depots, water-sealed cave oil depots, and offshore oil depots.

Of course, with the rapid development of digitalization and intelligence in the global oil and gas industry, the transportation, storage and use of oil and gas products are becoming safer, faster and smarter. They have entered thousands of households, ensuring the safe supply of national energy.

Author: Zhang Liehui