A Study Of Gas-oil Ratio In Gas Cap Oil Field On Lamadian

The key problem of gas cap oil field development is how to deal with the interrelation between gas area and oil area, the adopted exploitation strategy is to make the interrelation harmonious. Development practice shows that the separation technology of making water barrier has been applied on the Lamadian gas-cap oilfield to keep pressure equalization between gas cap and oil area, furthermore, the exploitation strategy that fulfill relative independence between gas cap and oil field is correct. But with the work of oilfield development further, the variation of pressure field compared with primitive development within strata becomes complicated, so that the relative stand-alone development between oil area and gas area gets more difficult. Presently, gas-oil ratio (GOR) in the second lease on Lamadian rises abruptly, which is a dangerous signal for gas-cap oilfield development anyhow, meanwhile, it directly influences oil production and next work program. Therefore, making sure the reason why the problem generates and providing solutions are a problem, which should be solved at once.It is well known that development engineering of hydrocarbon reservoir is a complicated system engineering, which has the characteristics of randomness and irreversibility. However, because the limited knowledge towards complicated system, we could not make a completed description of hydrocarbon reservoir. When system status is up to a bifurcation, the description of determinism is broken down. Types of random fluctuation in the system influence followed branch choices, striding bifurcation is a random process. Some kind of instability existing in the development process of hydrocarbon reservoir is regarded as the result of a random fluctuation. At the beginning, the fluctuation is usually restricted in a small section of the system, if positive feedback appears, it will extend further, and generate a new macroscopic state. Gas-oil ratio (GOR) rises abruptly on Lamadian is just derived from a macroscopic state formed by a series of accidental factors at bifurcation within the system.Exploitation strategy on Lamadian is always pressure maintenance production, and keeping balanced state or systems stability. Dissipation theory believes that systems stability could be described like this: a small quantity of new components join in a system, which makes a set of new reactions among these components, then the set of new reactions compete with its former active manner. If the system is "structural stability" towards the invasion, new active manner could not be established, moreover, this kind of innovators could not live on, either. But if structural fluctuation succeeds, these innovators could invade the system, change its former state, and the whole system will adopt a new active manner.On the basis of system engineering theory and dissipation theory, the paper researched the variable characteristics of gas-oil ratio (GOR) on Lamadian through material balance method, geophysical well logging method, gas-oil ratio (GOR) detection method and hydrocarbon detection method, etc. It believes that the reason why production gas-oil ratio (GOR) on Lamadian rises is unbalanced pressure in local area, which causes gas-cap gas interconnected with it sink downward. At the same time, the paper analyzes the main passage through which gas-cap gas sink downward and the reason why it forms, thus providing a theoretical basis for the next development regulation on Lamadian.