Gel breaking agent for preventing slurry from falling to ground and gel breaking method for waste drilling fluid

Abstract

The invention relates to a gel breaking agent for preventing slurry from falling to a ground and a gel breaking method for waste drilling fluid, belonging to the field of drilling technology. The gelbreaking agent provided by the invention is composed of hydrochloric acid and polyacrylamide. The gel breaking method for waste drilling fluid comprises the steps as follows: (1) slowly adding polyacrylamide particles into the waste drilling fluid, mixing the mixture uniformly, so that the dust particles in the drilling fluid are fully adsorbed on the polyacrylamide molecular chain; (2) adding hydrochloric acid into the waste drilling fluid obtained in step (1), adjusting the pH value of 7-8, reaching the effect of gel breaking by using the property that polyacrylamide molecular chain is broken in hydrochloric acid; (3) separating the solid and solution by using a plate-and-frame filter press or a high speed centrifuge, while the centrifuged liquid can be recycled in a drilling well directly. The gel breaking method provided by the invention can be used for breaking gel completely, both the solid chemical oxygen demand (COD) and the pH value after gel breaking meet the requirement of environment protection, and all of the fluid can be recycled in drilling wells, thus, the purposes of environment protection, cost reduction and effect improvement are reached.

Description

technical field [0001] The invention relates to a gel breaking agent for a mud not falling to the ground process and a gel breaking method for waste drilling fluid, belonging to the technical field of drilling. Background technique [0002] With the implementation of the new environmental protection law and the improvement of the environmental protection awareness of the whole people, the impact of drilling mud pits on the environment has attracted the attention of all walks of life. At present, the entire Chinese drilling industry has generally canceled the traditional mud pits and promoted the mud. The three non-environmental protection goals of "do not destroy the local landscape, do not leave waste, and do not pollute surface water". [0003] However, in the application process of the new type of slurry non-falling device, there are problems that the pH value of the waste solid phase exceeds the standard and the pressure filter water is difficult to reuse, mainly because...

AI Technical Summary

Problems solved by technology

[0004] At present, the gel breaking process that does not make the mud fall to the ground mainly uses high-priced cations such as PAC polymerized aluminum and polymerized iron to break the gel, and uses high-priced cations to reduce the electrical properties of the clay, so that the clay particles coalesce and become larger, and then the solid-liquid is achieved through a centrifuge or a filter press. However, this process has the following two major disadvantages: (1) The pH value of the drilling fluid is not acid-base neutralized in the whole process, and the pH value of some drilling fluids is as high as 10 or more, without acid-base neutralization, so that the solid-liquid separation The pH of the discarded cuttings is also above 10, which does not meet the national standard discharge requirements; (2) due to the introduction of high-valent cations in the liquid phase, if they are directly reused, these high-valent cations will have an impact on the stability of the drilling fluid, so At present, the waste liquid phase that does not land on the ground is basically not reused in major oil fields across the country, and is sent to sewage treatment plants for secondary treatment, with a large increase in cost

Images