Offshore oilfield micro-fracturing injection time calculation system and method

The invention discloses an offshore oilfield micro-fracturing injection time calculation system and method, and the method comprises the steps: modeling: collecting modeling parameters, and building aseepage and rock mechanics mathematic model; a simulation injection step: simulating injection of the micro-fracturing fluid, setting N1 injection time periods, and generating N1 post-fracturing fracture networks; an example execution step: executing the prediction example to obtain the discount yield increase of the well group; and a selection step: judging whether well group discount yield increase is in a descending trend or not, and selecting an injection time period corresponding to the after-pressure fracture network in the descending trend at first as injection time. By simulating theinjection time periods with different lengths and monitoring the well group discount yield increase of a plurality of post-fracturing fracture nets in real time, the injection time period corresponding to the post-fracturing fracture net with the well group discount yield increase reaching the first descending trend is finally selected as the optimal injection time. The optimal injection time is obtained, so that the optimal fracture network form is obtained, and the injection capacity of a single well is improved as high as possible under the condition that later water channeling is not caused.