Method for calculating critical discharge of horizontal well cement slurry

Abstract

The invention discloses a method for calculating the critical discharge of horizontal well cement slurry, and belongs to the technical field of oil and gas cementing. The method includes the following steps of: determining the temperature of a well bottom of a horizontal well and the pressure of the well bottom of the horizontal wellaccording to well track data and temperature log data; calculating a value range of a revolving speed corresponding to a value range of a shearing speed according to an instrumental constant of a rheometer on the premise of the known value range of the shearing speed of the cement slurry; selecting a revolving speed level of the rheometer in the value range of the revolving speed; measuring readings corresponding to different revolving speed levels, of the cement slurry under the temperature of the well bottom and the pressure of the well bottom; calculating the shearing speed and the shearing stress of the cement slurry; calculating rheological parameters according to the types of fluids of the cement slurry; and solving non-linear equations to obtain the critical flow speed, and then determining the critical discharge of the cement slurry. Through the method, the obtained critical discharge of the cement slurry accords with the actual situation of the site cement slurry, and the cementing quality can be improved.

Description

technical field [0001] The invention relates to a calculation method for critical displacement of cement slurry for horizontal well cementing, and belongs to the technical field of oil and gas well cementing. Background technique [0002] The well section with a well deviation of more than 85° and a horizontal extension of the target layer is called a horizontal well. According to different curvature radii, horizontal wells can be divided into three categories, namely, long-radius horizontal wells (curvature radius 914-305m, well deviation change 0.66-0.197° / m, horizontal well section length 610-1524m), medium and long-radius horizontal wells ( Curvature radius 213-28m, well inclination change 0.26-1.64° / m, horizontal well section length 457-610m) and short-radius horizontal well (curvature radius 12-6m, well inclination change 5-10° / m, horizontal well section length 91~122m). With the continuous improvement of drilling technology, the application of horizontal well drilli...

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Problems solved by technology

However, in view of the lack of applications of horizontal section cementing, especially long horizontal section cementing, in the early days of the drafting of the specification, it does not explicitly involve the content of horizontal section cementing of horizontal wells, and only includes rheological design schemes of Bingham and power law fluids, which do not meet The actual rheological properties of the cement slurry used on site, and the measurement and calculation of the rheological parameters of the cement slurry in the two rheological modes are all based on the values ​​under normal temperature and pressure, which is far from the actual rheological properties of the cement slurry under high temperature and high pressure environment, so the design The displacement of the pump must be inconsistent with the actual situation, which will easily cause large errors and cause the quality of cementing to decline

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