分析与计算地层渗透性漏失漏层深度和压力的新方法

New analysis and calculation method for permeable leakage layer depth and pressure

漏失对油气钻井及固井施工危害极大。针对利用现场常规数据无法用现有模型进行地层漏失信息计算的问题,以追溯漏失过程为出发点,利用非牛顿流体力学、渗流力学原理,研究了渗透性漏失漏层深度及压力计算模型的建立及计算问题。分析了漏失发生时间与钻井液漏失总量及钻头进尺的关系,建立了漏层深度与液体漏失总量的函数关系;依据渗透性漏失机理,建立了漏失压力、漏失流量及漏层厚度间的函数关系;提出了一种新的计算与分析漏层深度与压力的计算模型和方法,并对特定油田区块的漏失问题进行了计算与分析。该方法为准确确定地层漏失信息,合理选择与设计钻井液体系、水泥浆体系、钻井与固井施工参数提供基础。

Leakage creates extreme damage to oil and gas drilling and well cementation. Aiming at the problem that the leakage layer information cannot be figure out through existing calculation model with the on-site data, starting from stretching back leakage process, calculation model of permeable leakage layer depth and pressure was analyzed and established by utilizing nonewtonian fluid mechanic and seepage mechanics. Then we established functional relation between leakage depth and total amount of liquid leakage by analyzing the relation of leakage occurrence time, leakage amount of drilling fluid and bits footage; and figure out the function relation- ship among leakage pressure, leakage flow and thickness of leakage layer according to the permeability loss mechanism. Therefore, a new computation model which calculates the leakage depth and pressure was put forward and was applied to a particular block in some oil field to analyze the leakage problems. This method provides the basis not only for determining the leakage layer information ac- curately, but also for selecting and designing drilling fluid system, cement slurry and parameters of drilling and cementing reasonably.