Downhole drilling crosslinked gel leak stopping agent and leak stopping method thereof

Abstract

The invention relates to a downhole drilling crosslinked gel leak stopping agent and a leak stopping method thereof. Taking weight percent of the leak stopping agent as 100%, the leak stopping agent comprises 10-30% of a macromolecular polymer, 10-30% of a crosslinking agent, 0-20% of a coagulant or retarder, 10-30% of polymer fibers, 2-10% of a toughening agent and 10-30% of a dispersing agent. In the leak stopping agent, the coagulant is used for shortening crosslinking time, the retarder is used for prolonging the crosslinking time, and the coagulant or retarder also can not be added into a formula. The leak stopping agent has good leak stopping effect and also has retention and pressure-bearing capabilities; meanwhile, the pressure-bearing capability is strong, and gelling time is basically not influenced by salt invasion, drilling cuttings and the like.

Description

technical field [0001] The invention relates to a plugging agent for petroleum drilling, in particular to a downhole cross-linked gel plugging agent for drilling. Background technique [0002] At present, in the drilling work of complex oil and gas reservoirs, the problem of lost circulation has become increasingly prominent, especially the problem of vicious lost circulation. Due to its serious hindrance to normal drilling and serious threat to drilling safety, it has become an important technical bottleneck restricting the further development of China's exploration and development. Therefore, solving the problem of vicious leakage has become an urgent task for drilling engineering and even the entire petroleum industry. The so-called vicious leakage refers to the leakage with the following characteristics: (1) the leakage rate is too large to establish a normal circulation (such as "in and out", etc.); Or stop drilling; (3) It cannot be solved by conventional bridge plugg...

AI Technical Summary

Problems solved by technology

The so-called vicious leakage refers to the leakage with the following characteristics: (1) the leakage rate is too large to establish a normal circulation (such as "in and out", etc.); Or stop drilling; (3) It cannot be solved by conventional bridge plugging technology, or it cannot be solved by various common plugging technologies at present, or it cannot be solved within a few times

[0003] At present, the domestic and foreign technologies for dealing with large fractures and karst caves are mainly large particle and high-concentration bridge plugging slurry technology, cement slurry plugging technology, clear water strong drilling measures, etc. The disadvantages are: (1) due to the large leakage channel , it is very difficult to achieve high-strength plugging only by bridge plugging materials; (2) due to reasons such as formation water, the retention capacity of cement slurry in the leakage layer is insufficient, and the cement slurry diluted by formation water cannot form an effective sealing layer; ( 3) Strong drilling in clean water requires good geological and engineering conditions, such as the stability of the borehole wall and sufficient water resources in the drilled well section

The polymer gel is used as a plugging agent, and its disadvantages are: (1) The gel formed by the polymer has a low bursting pressure, and the leaky layer will be reopened under the condition of a large negative pressure difference in the drilling fluid; (2) Complex downhole conditions have a great impact on polymer gelation, and some even fail to gel, resulting in plugging failure

CN102618230A discloses "a controllable cross-linked gel water plugging and leak plugging material for oil and gas fields". Its technical solution is to first make a water-absorbing resin, then wrap the particles with oil phase, and add the particles to the HPAM aqueous solution for cross-linking reaction. Obtain immobile gel, which can plug fractured and karst cave formations, but this plugging material has poor fluidity in pipelines and drill strings