The invasion law of drilling fluid along bedding fractures of shale

In the process of drilling, drilling fluid will invade into bedding plane shale under action pressure difference that cause hydration collapse and wellbore instability. order to ensure stability during oil gas it is necessary clarify invasion law along fractures process. The immersion experiment method often used study fluid, which quite different from actual underground. this paper, depth confining pressures displacement times intuitively accurately determined by NMR scanning first. Also, then mathematical relationships between time, difference, pressure, angle, viscosity were established. errors calculated values experimental less than 15%, calculation accuracy was high. addition influence formation on researched through numerical simulation. results showed liquid increased logarithmically with increase time but grew slowly in later period tended be stable; decreased exponentially viscosity. paper provide a basis for subsequent determination shale.