Drilling an oil and gas well is very expensive. Under normal circumstances, deep Wells need tens of millions of YUAN, shallow Wells also need one or two million yuan.If the construction of ground pipeline and other projects, the investment is more considerable.But since oil is called "black gold", the payback period is also short.Some Wells pay their full cost in just a few months, as long as five or six years.Therefore, it is an important mission for investors and managers to extend the productive life of oil Wells as much as possible.
So how long is the life of the well?This is a very difficult question to answer.The lifespan of an oil well cannot be determined by calculation or expert judgment, or even by human control.Like a person's life expectancy, experts predict it can reach 120 to 150 years.In fact, due to the influence of diet and environment, the world's average life expectancy is only about 75 years.The same is true of oil Wells, whose life is mainly restricted by engineering, geology, development technology and casing pipe.For example, in engineering, in the process of drilling and completion, a vicious underground accident is caused, so that it cannot be dealt with and the oil well is aborted;In geology, the reservoir is completely flooded or completely exhausted and cannot be used for other purposes.In terms of management, the production system is unreasonable, resulting in oil and gas reservoir flooding;In terms of the development process, the casing pipe is severely damaged (corroded, broken, bent, crushed) due to unreasonable control of the well production system or improper construction, which cannot be repaired;Pipe, casing pipe quality is not qualified, the pipe itself has bubbles, holes or cracks.All the above reasons will shorten the life of oil Wells and lead to early abandonment.
However, a well can be produced for a decade, two or three decades or longer if the reservoir is well conditioned and controlled from well drilling to production.For oil workers, however, we are more concerned with the life of an oil field.An oil field may be either an oil-bearing structure or composed of several oil-bearing structures.Even if an oil and gas field is formed by a structure, because modern science and technology can only produce 30% ~ 40% of the underground oil and gas reserves, the oil field has to continuously drill or supplement part of the new Wells, or use more advanced technology to extract as much underground resources as possible.In this way, the life of an oil field can be as long as 100 years.For example, yanchang oil mine in northern Shaanxi of China is the earliest oil field discovered and developed in mainland China. It has been 100 years since the establishment of Yanchang Oil Official Plant in 1905, but it still maintains a considerable production capacity.
People are born, get sick and die, and oil and gas Wells are no exception.When an oil or gas well is not recoverable or useful, the technical term is a scrapped well or scrapped well.These Wells must be professionally treated.For the scrapped oil and gas Wells with edge water or bottom water, cementing should be used to seal the oil layer and other parts should be filled with sand and other materials to prevent groundwater from flowing into other Wells and causing oil layer water flooding.For abandoned Wells that have been proved to be free of water, oil and gas, sand or other substances can be used to plug the wellbore after the casing is removed.For the scrapped Wells with productive capacity but due to engineering reasons, each layer shall be sealed to prevent each other from flowing through, and then the wellhead shall be sealed and marked on the ground.