Lecture 11 Gravel Pack Well Completion

Lecture 11Gravel 11Gravel Pack Completion

NOK 40 questions on Monday 9 questions from lecture 8: 1,2,3,29,102,129,131,135,136,137 16 problems from lecture 10: 9,11,14,18,19,31,74,98,100,108,109,110,112,128,130,155 Additional 15 questions: 4,5,6,7,16,21,22,23,33,35,36,40,42,44,45

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Gravel pack completion should be adopted toward unconsolidated formations with serious sand production

1. a wire-wrapped screen is run to the position of the oil reservoir 2. gravel selected at the surface in advance is pumped to the annulus between the wirewrapped screen and the borehole(open hole completion) or between the wire-wrapped screen and the casing using packing fluid (cased hole completion)

The stainless steel wire-wrapped screen is generally used, but not the slotted liner Reasons: The minimum width of the slot opening of the slotted liner is 0.5 mm due to the limitation of cutter strength. Thus, the slotted liner is only suitable for mediumcoarse grain reservoirs. However, because the minimum gap width of the wire-wrapped screen is 0.12 mm, its applicable range is much larger

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wire-wrapped screen has a continuous gap formed by the wrapping wire. Their flow areas are much larger than that of the slotted liner

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The wire used for the wire-wrapped screen is a stainless steel wire with strong corrosion resistance, long service life, and high economic benefits.

Open Hole Gravel Pack Completion

Procedure: 1. drilling to 3 m above the top boundary of the oil reservoir, 2. running intermediate casing, 3. cementing, 4. drilling through the cement plug with a smaller bit, drilling-in the oil reservoir to design depth, 5. changing into the under-reaming expansion bit, enlarging the borehole diameter up to 1.5 –3.0 times the outside diameter of the intermediate casing in order to ensure a larger annulus during gravel packing, an increased thickness of the sand control bed and an enhanced effectiveness of sand control, and then packing gravel. Generally, the thickness of the gravel bed is not less than 50 mm

Size Matching of Underreaming for Open Hole Gravel Pack

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Casing Gravel Pack Completion Procedure: Drilling through the oil reservoir to design depth running production casing to the bottom of the oil reservoir Cementing perforating the oil reservoir. During perforating, a high perforation density (30 –40 perforations/m) and a large perforation diameter (20 –25.4 mm) are required in order to increase flow area. Sometimes the reservoir sand outside the casing may be washed out in order to pack gravel into the location of the oil reservoir outside the perforations to avoid mixing of gravel with formation sand and increasing flow resistance. •

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Open and Cased Hole Gravel Packs

Pre-packed sand screen

Gravel Packing fluids  Hydroxyethyl cellulose or polymer.

High density packing is adopted with a gravel-carrying volume ratio up to 96% (12 lb/gal), that is, 1 m3 fluid should pack 0.96 m3 gravel. with a gravel-carrying volume ratio of 8 –15% (1 –2 lb/gal), which can avoid the possible formation damage induced by the high-viscosity, gravel-carrying fluid.

 Low-viscosity salt water

Gravel Quality Requirements •

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Gravel grain diameter selection: The recommended grain diameter of gravel is five to six times the median grain diameter of reservoir sand. Qualified degree of gravel size : content of gravel larger than the required size in the gravel sample should not exceed 0.1%, smaller than the required size should not exceed 2%. Strength of gravel: Weight Percentage of Crushed Gravel should be between 2-8%

Casing gravel pack animation •

https://www.youtube.com/watch?v=Xdsis-miiYc