Exercise 10 Cement Flow Regime

Exercise 10 Cement Flow Regime - MEMO Drilling Lab 10 TO:...

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MEMO Drilling Lab 10 TO: District Engineer FROM: student name Memo style +0.5 pt RE: General Well Planning Recommendations: Using the data from your memo I recommend the H cement slurry with 0.6% Halad 344 to cement production casing. This slurry has the lowest water loss of the slurries tested which will improve cement bond to the formation. This slurry has a density of 15.8 ppg which produces a pressure gradient of 0.821 psi/ft. The critical velocity for this slurry to achieve turbulent flow in the annulus is xxx ft/sec. The pump rate to achieve critical velocity is xxx bbl/min. In the event the density of this slurry is too high to prevent fracture an alternate slurry is the 50-50 Poz mixture with H. This slurry has a higher water loss at 48 ml/30 min, but has a lower density of 14.1 ppg and a resulting smaller pressure gradient of 0.733 psi/ft. Comments along these lines, with at least the choice of the H with the Halad additive for +2 pts. Discussion: The pressure gradient for each slurry shown in Table 1 is shown in Table 3. Cement Density API Filtrate Blow Thru Viscometer Readings 10 min Gel Free Water (ppg) (ml/30 min) (min) 300 rpm 200 rpm 100 rpm 6 rpm (lb/100 sqft) Content (%) H neat 16.3 180 2.5 68 55 39 16 21 2.4 H + 0.6% Halad 344 15.8 trace NA 129 90 50 5 3 0.0 H + 10% NaCl 16.5 72 NA 58 47 35 16 18 2.2 50% H + 50% Poz 14.1 48 NA 29 24 19.5 12.5 11 3.2 H + 2% Econolite 11.1 133 1.92 21 17 14 7 14 4 H + 8% Bentonite 13.4 116 0.5 152 141 132 60 53 1 Table 1 – Cement Data Original Data shown some where in the memo +0.5 pt. Casing OD Weight Grade Coupling Hole Size (in) (ppf) (in) 4 1/2 11.6 N-80 LTC 7 7/8 Table 2 – Well Data Cement Density Pressure Gradient (ppg) (psi/ft) H neat 16.3 0.848 H+0.6% Halad 344 15.8 0.822 H+10% NaCl 16.5 0.858 50% H + 50% Poz 14.1 0.733 H + 2% Econolite 11.1 0.577 H + 8% Bentonite 13.4 0.697 Table 3 – Pressure Gradients Table is +1 pt.
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A graph of shear stress versus shear rate for the H slurry with 0.6% Halad 344 is shown in Figure 1. Graph is +2 pt. H + 0.6% Halad 344 0 20 40 60 80 100 120 140 160 0 100 200 300 400 500 600 Shear Rate (1/sec) Shear Stress (lb/100 sqft) Figure 1 – Shear Rate vs Shear Stress Using the end point of the data the plastic viscosity is 129 cp and the yield point is 4.9 lb/100 sq ft. The students may choose to use the best fit line to the data or even a line that starts at zero, so any value that is close for viscosity and yield point is acceptable. +2 pts The yield point is very close to zero, so the Newtonian Fluid Model is used to approximate the critical velocity and pump rate for this slurry. Critical flow in the annulus is given by:
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This note was uploaded on 02/13/2012 for the course PGE 430 taught by Professor Chenevert during the Spring '06 term at University of Texas at Austin.

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Exercise 10 Cement Flow Regime - MEMO Drilling Lab 10 TO:...

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