35.What happens after petroleum is taken out of oil well? short answer
Answers
Answer:
Even if oil is being produced from one formation (deep into the earth), there is very remote chance that there would be empty space.
Most oil and gas deposits are found in sandstones and coarse-grained limestones deep inside the earth. A piece of sandstone or limestone is very much like a hard sponge, full of holes, but not compressible. These holes, or pores, can contain water or oil or gas, and the rock will be saturated with one of the three. The holes are much tinier than sponge holes, but they are still holes, and they are define as porosity of the rock.
Oil and gas are formed owing to thermo chemical reactions of organic materials sedimented deep inside the earth over millions of year, the organic materials could be Plants , dead bodies of animals, organic presents at sea bed and so on.
It is the trillions of tiny animals that make up most of the gunk,deposited on the ocean floor. It’s a very fine-grained goop containing a lot of organic material mixed with the clay-sized particles that form shale. It is called organic-rich shale.
Later, when thousands of feet of organic-rich shales have piled up over millions of years, and the dead animal bodies are buried very deep (more than two kilometers down), an amazing thing happens. The heat from deep inside the earth “cooks” the animals, turning their bodies into what we call hydrocarbons……oil and natural gas.
The oil and gas once produced start migrating all over inside the formation through pore spaces, till their path is blocked by impermeable formation (Anticline) or through which oil and gas could not pass through and gets trapped.
If we hold a piece of sandstone containing oil in the hand, the rock may look and smell oily, but the oil usually won’t run out, and it can’t squeeze sandstone like a sponge. The oil is trapped inside the rock’s porosity.
The oil trapped inside has potential energy due to the pressure at which it is stored or trapped there. Geologists carry out studies , well is drilled and oil starts getting produced, generally it is self flow owing to the pressure at which it is trapped which gives potential energy to flow to surface. Source rock too, from where the oil is produced and migrated, continues to add /flow the oil in the pool, till it gets exhausted.
No matter, how advance technology is used, entire oil and gas can not be produced from the reservoir below the earth. After few years of producing the oil and gas, the potential energy starts decreasing owing to reduction in formation pressure and the production starts declining and ceases after some time. There are few techniques for secondary recovery, still around 30% oil remains unrecovered and rest in the pores.
Thus the pore space of reservoir will always have some hydrocarbon. The overburden of earth above the structure would move the pore spaces closer or blocked even if entire hydrocarbon is produced from the reservoir. The chances of occurrence of such scenario are very remote.