Weak gel modifying and flooding agent for medium-temperature oil reservoir and preparation method of weak gel modifying and flooding agent

The invention provides a weak gel modifying and flooding agent for medium-temperature oil reservoirs. The weak gel modifying and flooding agent comprises the following components in parts by weight: 0.1-0.2 part of a polymer, 0.1-0.2 part of an organic acid aluminum cross-linking agent, 0.05-0.2 part of an aldehyde organic cross-linking agent and the like. The invention also provides a preparation method of the weak gel modifying and flooding agent, which comprises the following steps: adding the water and the modifier into a container, and stirring for dissolving; adding a polymer, stirring until the polymer is fully dissolved, and standing; and adding an organic acid aluminum cross-linking agent and an aldehyde organic cross-linking agent, and stirring to obtain the weak gel modifying and flooding agent. The weak gel profile control and flooding agent can react at 50-80 DEG C to generate weak gel, the initial setting time is controllable in 5-48 h, the initial gel viscosity is adjustable in 400-1000 mPa.s,