Weighted spacer fluid for well cementing at oilfields and preparation method of weighted spacer fluid

Abstract

The invention relates to weighted spacer fluid for well cementing at oilfields. The preparation method sequentially comprises the following steps of: (1) preparing raw materials comprising the following components in parts by weight: 100 parts of clean water, (0.90-0.1) part of an HS-GYW301 separant, (3.0-3.8) parts of an HS-GYW201 separant, (0.2-0.3) part of an HS-ZNJ tackifier, (5-10) parts of an HS-GHJ activator ,(10-15) parts of an HS-ZQJ early strength agent, and (85-100) parts of barite; (2) firstly putting the HS-GYW301 separant and the HS-GYW201 separant in the clean water, and uniformly stirring the HS-GYW301 separant, the HS-GYW201 separant and the clean water; (3) then putting the HS-ZNJ tackifier to the mixed fluid obtained in the step (2), and uniformly stirring the HS-ZNJ tackifier and the mixed fluid obtained in the step (2); (4) then putting the HS-GHJ activator and the HS-ZQJ early strength agent to the mixed fluid obtained in the step (3), and uniformly stirring the HS-GHJ, the HS-ZQJ early strength agent and the mixed fluid obtained in the step (3); and (5) finally, putting the barite in the mixed fluid obtained in the step (4), and uniformly stirring the barite and the mixed fluid obtained in the step (4) so as to obtain the spacer fluid. The spacer fluid disclosed by the invention has excellent anti-pollution capacity and has favorable chemical compatibility with various well drilling fluid systems and various cement grout systems; the spacer fluid can improve interface cementation environment, and improve interlayer seal quality; a spacer fluid system has high intensity, and a borehole annulus space can be filled at slurry mixing segments or spacer fluid existing segments.

Description

Technical field [0001] The invention relates to a weighted isolation fluid for oilfield cementing. The invention also relates to a preparation method of a weighted isolation fluid for oilfield cementing, belonging to the technical field of oilfield cementing. Background technique [0002] Since the mutual contact pollution of drilling fluid and cement slurry endangers the safety of cementing construction and affects the cementing quality, the cementing slurry is often very smooth in cementing, but the electrical logging cementing quality is not good or the annulus is mixed with liquid after cementing. The results of non-cemented materials such as gaseous state showed that a complete cement ring was not formed, the quality of the interface cement was poor, and the purpose of good interlayer isolation was not achieved. The main reasons are as follows: First, the rheological properties of the drilling fluid before cementing are poor, the mud cake formed during the drilling process h...

AI Technical Summary

Problems solved by technology

[0002] Because the drilling fluid and cement slurry contact and pollute each other, the safety of cementing construction is endangered and the cementing quality is affected. During cementing, the cementing slurry operation is often smooth, but the cementing quality is not good after cementing, or the annular space is mixed with liquid, The results of non-cemented materials such as gaseous state show that a complete cement sheath has not been formed, the interface cementation quality is poor, and the purpose of good interlayer isolation has not been achieved

Analysis of the reasons mainly includes: first, the rheological properties of the drilling fluid before cementing are poor, the properties and quality of the mud cake formed during drilling are poor, and the gelled drilling fluid is attached to the well wall, which seriously affects the cementing quality

Second, the drilling fluid and cement slurry are contaminated by mutual contact, which seriously affects the rheological properties of drilling fluid and cement slurry, resulting in a decrease in displacement efficiency and affecting the improvement of cementing quality

[0005] The performance of the currently commonly used spacer fluid system cannot meet the requirements after being aggravated. The suspension stability of the spacer fluid system is improved by increasing the viscosity of the system, and the increase in viscosity will lead to poor rheology of the system.

For example, the weighted spacer liquid system prepared by using CMC as a suspending agent has poor static suspension stability, obvious stratification, and pollution problems.