AdvancesintheTechnologyofFormationDamageControl保护油层技术.pptVIP

The Concept Technical Key Points of D90 rule The D90 Rule： The ideal packing can be achieved when the D90 of Particle size distribution matches to the largest pore size of target formation. Technical Key Points： Plot a target line for a given formation Optimize the particle size distribution of bridging agents and enable the PSD curve coincides with (or close to) the target line How to Plot Target Line for a Given Formation? Establish a coordinate system of cumulated vol.% ～(d)1/2 Determine the largest pore diameter which is equal to D90 by use of the results of mercury injection tests or thin section analysis The target line of formation can be plotted by linking the D90 point with the origin of coordinates If the largest pore diameter of formation is not available, the value of D90 can be estimated by (kmax)1/2 ? D90 (Dick,et al., 2000). Example：Assuming the largest pore diameter of a sandstone formation is 133mm，which means (d90)1/2 = 11.53mm，the target line can be plotted below: d90 (133)1/2 = 11.53mm How to Optimize the PSD? It is very difficult for a single bridging agent to match the target line of formation “The ideal packing” can be realized by mixing several grades of CaCO3 in a proper ratio. The related methods and software have been developed in our research group and applied in the fields. The Best Mixture of Particle Size to Protect Formation with the Largest Pore Size of 133mm d*(1/10)d Total mud invasion d* (1/3)d Form external cake (1/10)dd*(1/3)d Particles of solids Mud filtrate Oil phase d*: d : Median Pore diameter Invasion Control —— Older bridging rule proposed by Abrams (JPT, May 1977) Form internal cake Median Particle diameter According the rule, The median particle size of bridging material should be equal to or slightly greater than 1/3 the median pore size of formation. Schematic of new old bridging rules Choosing PSD Abrams’s rule Ideal Packing Theory with Idea