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Method to Measure and Characterize Accretion of Materials onto Metal Surfaces

IP.com Disclosure Number: IPCOM000239910D
Publication Date: 2014-Dec-11
Document File: 6 page(s) / 577K

Publishing Venue

The IP.com Prior Art Database

Abstract

Abstract In some drilling operations drill pipe and other metal surfaces may fouled or coated with asphaltene, other tar-like sticky materials or sticky shales. These accreting materials may come from cuttings or the wellbore wall. Accretion can become problematic and detrimental to drilling operations, resulting in large amounts of non-productive time (NPT). Some potential drilling problems may include: 1. Excessive ECD 2. Excessive surge and swab pressures 3. Excessive torque and drag 4. Stuck pipe 5. Poor cement bond strength 6. Low rate of penetration (ROP) 7. Excessive fluid viscosity 8. Surface equipment fouling 9. Excessive NPT

Oftentimes accretion materials can be very difficult to remove or prevent with chemical or mechanical means. A method to measure and test the the accretion nature of cuttings is described herein. These methods are useful in the study of accretion phenomenon and the development of inhibition agents and/or drilling fluids to eliminate or minimize accetion problems in the field.

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Method to Measure and Characterize Accretion of Materials onto Metal Surfaces

Dale Jamison

Halliburton Energy Services

Abstract

In some drilling operations drill pipe and other metal surfaces may fouled or coated with asphaltene, other tar-like sticky materials or sticky shales. These accreting materials may come from cuttings or the wellbore wall. Accretion can become problematic and detrimental to drilling operations, resulting in large amounts of non-productive time (NPT). Some potential drilling problems may include:

1.     Excessive ECD

2.     Excessive surge and swab pressures

3.     Excessive torque and drag

4.     Stuck pipe

5.     Poor cement bond strength

6.     Low rate of penetration (ROP)

7.     Excessive fluid viscosity

8.     Surface equipment fouling

9.     Excessive NPT

Oftentimes accretion materials can be very difficult to remove or prevent with chemical or mechanical means. A method to measure and test the the accretion nature of cuttings is described herein. These methods are useful in the study of accretion phenomenon and the development of inhibition agents and/or drilling fluids to eliminate or minimize accetion problems in the field.

Traditional Method and Issues

Very large amounts of material may accrete onto suraces of drill pipe, bits and casing. In figure 1 is an example of a drill bit with cutting accretion. In this example, cutting materials stuck to the bit may inhibit ROP and is commonly known as bit balling. In this example, a high performance water based drilliing fluid was used to mitigate the accretion nature of the cuttings onto the bit. The image on the left is a clean bit using a high performance water mud, while the image on the right shows a bit with undesirable accretion.

Figure 1-http://www.drillingcontractor.org/dcpi/2002/dc-mayjune02/may2-mi.pdf

Some products have been developed to chemically inhibit accretion or remove accretion materials . A method to measure the accretion or build-up of materials onto metal surfaces in the laboratory that has been used forseveral years is shown below.  Shown In Figure 2, this method uses a metal rod, 3, placed inside a pressurized mud testing vessel/cell, 4, with a test fluid, 7, and cuttings, 5, or other materials suspected of having an accretion issue. The vessel/cell is put on rollers, 1, in a roller oven, 8, to heat to testing temperature and continuously roll, 9, the metal rod, 3, inside the cell.

Figure 2 – Typical Accretion test set up

As the accretion test progresses the accreting material will stick to the rod and build up. The build-up rate will depend on the sticky nature of the materials/cuttings, temperature, the metal surface material and finish and the chemistry environment. Typically,  accretion tests continue for 16 hours or longer. After rolling, the cell is removed from the oven, cooled and disassembled. The sticky mass accreted to the rod is weighed and accretion character evaluated based on mass build-up. Figure 3 and 4 shows accretion materials stuck to the rod after tes...