海上稠油砂岩油藏启动压力梯度测定方法及应用——以秦皇岛32-6油田为例

对于海上稠油砂岩油藏非达西渗流规律的相关研究较少，尤其是在启动压力梯度研究方面，且多采用管流模型，较少考虑粘度对启动压力梯度的影响。根据海上稠油砂岩油藏的渗流特点，设计了测定启动压力梯度的实验新方法，并采用与秦皇岛32-6油田渗透率级别相近的天然岩心，通过对不同原油粘度、渗透率和温度下的岩心渗流实验，研究了稠油在多孔介质中的渗流特征，得到了海上稠油砂岩油藏启动压力梯度和流速与压力梯度的关系；通过对实验数据的回归，进一步得到了流度与启动压力梯度的关系式。实验结果表明：启动压力梯度受原油粘度和储层物性的影响，将研究结果应用于海上稠油砂岩油藏，建立了根据启动压力梯度确定技术极限井距的理论计算方法。鉴于启动压力梯度对稠油油藏开发的重要性，建议将启动压力梯度与流体饱和度、孔喉半径、边界层厚度的定量分析作为今后研究重点。

Experimental method and its application on threshold pressure gradient for offshore sandstone in heavy oil reservoir: a case study of QHD32-6 oilfield

Fewer studies are addressed about the non-Darcy seepage rule of the offshore heavy oil reservoirs at home and abroad, especially in the aspects of threshold pressure gradient, but the phenomenon is very important for offshore heavy oilfield development, and for in-depth research. According to the percolation characteristics in heavy oil reservoir, a new experimental method for rational determination of the threshold pressure gradient is designed, by which the threshold pressure gradient of heavy oil and flux mobility are deduced using the similar natural cores from QHD32-6 oilfield. The empirical formulas of relations between the threshold pressure gradient and the flow mobility are obtained by regression experimental data. The experimental results indicate that: the threshold pressure gradient is influenced by crude oil viscosity, permeability, and temperature. Through the linear regression above, we can propose the calculation method to determine the technical limit of well spacing and then apply it to the QHD32-6 oilfield. The study above can provide theoretical basis for the offshore development of heavy reservoir.