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A Drilling Fluid Displacement Determination Method for Special-shaped Hole Cleaning
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A determination method and drilling fluid technology, applied in wellbore/well components, flushing wellbore, earth-moving drilling, etc., to achieve the effect of reasonable regulation, safe and efficient drilling
Active Publication Date: 2021-01-29
CHINA PETROLEUM & CHEM CORP +1
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[0007] The purpose of the present invention is to solve the problems existing in the above-mentioned prior art, to provide a method for determining the displacement of drilling fluid that satisfies the cleaning of special-shaped boreholes, and to solve the problem of adjusting the displacement of drilling fluid based on experience or based on regular boreholes at the drilling site
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Embodiment 1
[0088] (1) Obtain the basic drilling parameters as shown in Table 1:
2700 Cuttings equivalent diameter Dd,m 0.005 Well diameter enlargement rate 100％ Initial cuttings concentration at borehole enlargement 10％
[0090] Table 1
[0091] (2) Establish the geometric model of the special-shaped wellbore, divide the grid, and intensify the grid at the special-shaped wellbore, such as figure 2 shown.
[0092] (3) Drilling fluid samples were taken at the elevated trough, and a set of shear rates and shear stresses were measured with a rotational viscometer, as shown in Table 2.
[0102] The basic parameters of drilling and the shape of the special-shaped wellbore are the same as in Example 1. Under the rheological conditions of the drilling fluid in Example 1, there is no displacement range that meets the requirements of wellbore cleaning. In Example 2, by adding drilling fluid additives , to adjust the rheology of drilling fluid. The adjusted drilling fluid rheology is shown in Table 4.
[0105] According to the shear rate and shear stress, four kinds of rheological models were regression fitted, and the Herba-Ba model with the largest correlation coefficient was determined as the rheological type used for calculation, as shown in Table 5 and Figure 8 shown.
[0106] ...
Embodiment 3
[0112] (1) Obtain the basic drilling parameters as follows:
2700 Cuttings equivalent diameter Dd, m 0.005 Well diameter enlargement rate 79％ Initial cuttings concentration at borehole enlargement 10％
[0114] Table 6
[0115] (2) Establish the geometric model of the special-shaped wellbore, divide the grid, and intensify the grid at the special-shaped wellbore, such as Figure 13 shown.
[0116] (3) Drilling fluid samples were taken at the elevated trough, and a set of shear rates and shear stresses were measured with a rotational viscometer, as shown in Table 7.
[0117]
[0118] Table 7
[0119] According to the shear rate and shear stress, four kinds of rheological models are regression fitted, and the correlation coefficients of each model are calculated: Bi...
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Abstract
The invention provides a method for determining the displacement of drilling fluid that satisfies the cleaning of special-shaped well holes, and belongs to the field of oil and gas exploration and development drilling. The method described in this method first establishes a geometric model of a special-shaped wellbore based on the basic drilling parameters, sets the initial displacement, and then obtains the cuttings concentration distribution at each position of the wellbore in a stable state through numerical calculation, and judges whether the cuttings concentration distribution meets the requirements of the wellbore. to determine whether the drilling fluid displacement is within the reasonable displacement range, and if one is not, then adjust the rheology of the drilling fluid, and then repeat the above process until the drilling fluid displacement meets the wellbore cleaning effect and is within a reasonable displacement. Within the volume range, the drilling fluid displacement at this time is the final drilling fluid displacement. The present invention can overcome the shortcomings of the existing empirical method or the annular hydraulic method based on regular boreholes, and solve the problem of insufficient precision in adjusting the displacement of drilling fluid in special-shaped boreholes only by experience or the annular hydraulic method at the drilling site.
Description
technical field [0001] The invention belongs to the field of petroleum and natural gas exploration and development drilling, and in particular relates to a method for determining the displacement of drilling fluid that satisfies the cleaning of special-shaped well holes. Background technique [0002] Drilling fluid is a fluid medium that circulates and carries cuttings during drilling. Wellbore cleanliness refers to the state of cuttings carried in the wellbore during drilling. The state of cuttings carrying in drilling is directly related to drilling speed and downhole safety, and is a very important drilling parameter. During the drilling process, if the cuttings cannot be carried out of the wellbore in time, it may cause downhole complex situations such as difficulty in running in, incomplete running in, and sticking. Therefore, wellbore cleaning has become the primary issue of safe and fast drilling. [0003] Practice has shown that the shape of the wellbore, the disp...
Claims
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