Oil-water separator and method for separating oil-water mixed solution in oil field

The invention discloses an oil-water separator which comprises an upper outer pipe and a lower outer pipe, wherein the upper outer pipe and the lower outer pipe are communicated through at least one vertical pipe; the top end of the upper outer pipe is fixedly connected with a floating oil pipe extending along the axial direction, and an oil outlet for communicating the upper outer pipe with the floating oil pipe is arranged in the top end of the upper outer pipe. A method for separating an oil-water mixed solution in an oil field comprises the following steps: (1), primarily separating crude oil and water in the oil-water mixed solution in the oil field by adopting a 'gravity settling process', directly collecting settled sewage and floating crude oil in a primary separation process; and (2), secondarily separating settled sewage and floating crude oil in the step (1) by adopting a 'gravity settling process', and respectively collecting floating pure crude oil and settled pure water in a secondary separation process. The oil-water separator has the beneficial effects of ensuring the miniaturization, ensuring stability of the dewatering quality, enabling the gravity settling efficiency to be greatly increased, and greatly lowering the project cost of existing separation facility.