A multi-slug step-by-step plugging method suitable for fractured formations

Abstract

The present invention relates to a multi-slug staged plugging method suitable for fractured formations, comprising: step 1) determining the average opening of the fractures around the well as D, and using bridging particles with a particle size slightly smaller than D in the first-stage plugging. The average particle size is expressed as D 1 , the average particle size D of the plugging particles is used for the secondary plugging 2 greater than D 1 / 4, and less than D 1 , use the same method to determine the particle size of the following plugging particles in sequence, until the average particle size of the last stage of plugging particles is D n Small enough to form a tight plugging layer; step 2) first inject through the slug containing only 1 The plugging slurry of bridging particles forms a layer of bridging particles; step 3) injects the plugging particles with an average particle size of D through multiple slugs 2 ~D n‑1 plugging slurry to form a particle packing layer; step 4) use a slug to finally inject a plugging slurry with an average particle size of plugging particles Dn to form a tight sealing layer. The invention has a reliable principle, more effectively seals the cracks around wells, saves costs, and has broad application prospects.

Description

technical field [0001] The invention relates to a multi-segment staged leak plugging method suitable for fractured formations in drilling plugging operations in the field of oil and gas field exploration and development. Background technique [0002] When severe drilling fluid loss occurs in the drilling process of petroleum engineering, it is often caused by natural fractures in the well or induced fractures caused by bottomhole pressure. In order to eliminate or reduce the loss, it is necessary to seal the fractures around the well according to the actual engineering situation. The usual practice is to add plugging materials of different particle sizes and types to the drilling fluid according to the amount of leakage and the location of the leakage, and then inject it downhole at one time to seal the fractures around the well. The basic principle of the formation of plugging is that larger-sized particles form a bridge in the narrow part of the fracture, which narrows the...

AI Technical Summary

Problems solved by technology

[0003] (1) Changes in wellbore fluid column pressure will cause dynamic deformation of formation fractures, which will change the position, plugging state, and pressure bearing capacity of the original effective sealing layer, which may cause damage to the sealing layer, resulting in repeated leakage;

[0004] (2) Plugging particles of different particle sizes are mixed in the plugging working fluid. Before a tight seal is formed, some small-sized particles will leak into the formation through the gap between the fracture channel and the large-sized particles, resulting in the loss of plugging particles. waste, which increases costs;

[0005] (3) For fractured reservoirs, fractures are the main flow channels for oil and gas migration, so the production of fractured reservoirs is much higher than that of other reservoirs, and during the drilling plugging process, the lost plugging particles enter the formation through fractures Throats block the channels for oil and gas production, greatly reducing production and causing solid particle intrusion damage

Images