Horizontal well indoor seepage simulation test device and simulation test method

The invention provides a horizontal well indoor seepage simulation test device and a simulation test method. A seepage sand tank is a hollow cuboid without a cover, and is divided into a control boundary box body and a sand tank box body by a partition plate in the length direction; small supply holes are formed in the partition plate; the sand tank box body is filled with a simulated formation material; micro hole pressure sensors are embedded in the simulated formation material in the radial direction and the tangential direction; the control boundary box body is provided with a liquid inlet, a plurality of overflow ports with different heights and scale lines, and is filled with a simulated fluid; an adjusting valve and a flow buffer are arranged at the liquid inlet; each overflow port is independently controlled by a valve; a constant-flow constant-pressure pump supplies the fluid to the simulated formation; a mounting hole is formed in the side wall, opposite to the partition plate, of the sand tank box