Basic solids analysis calculations

NOTE: Steps 1 — 4 are performed on high salt content muds. For low chloride muds begin with Step 5.

Step 1 Percent by volume saltwater (SW)

SW = (5.88 x 10-8) x [(ppm Cl)12+1] x % by vol water

Step 2 Percent by volume suspended solids (SS) SS = 100—%by vol oil — % by vol SW

Step 3 Average specific gravity of saltwater (ASGsw) ASGsw = (ppm Cl)095 x (1.94 x 10-6) + 1

Step 4 Average specific gravity of solids (ASG)

ASG = (12 x MW) — (% by vol SW x ASGsw) — (0.84 x % by vol oil)

Step 5 Average specific gravity of solids (ASG)

ASG = (12 x MW) — % by vol water — % by vol oil % by vol solids

Step 6 Percent by volume low gravity solids (LGS)

Step 7 Percent by volume barite

Barite, % by vol = % by vol solids — % by vol LGS

Step 8 Pounds per barrel barite Barite, lb/bbl = % by vol barite x 14.71

Step 9 Bentonite determination

If cation exchange capacity (CEC)/methytene blue test (MBT) of shale and mud are KNOWN: a) Bentonite, lb/bbl:

Bentonite, lb/bbl = 1 — (1— (S — 65) x (M— 9 x (S — 65)) x % by vol LGS Where S = CEC of shale M = CEC of mud b) Bentonite, % by volume:

If the cation exchange capacity (CEC)/methylene blue (MBT) of SHALE is UNKNOWN: a) Bentonite, % by volume = M — % by volume LGS

where M = CEC of mud b) Bentonite, lb/bbl = bentonite, % by vol x 9.1

Step 10 Drilled solids, % by volume

Drilled solids, % by vol = LGS, % by vol — bentonite, % by vol

Step 11 Drilled solids, lb/bbl

Drilled solids, lb/bbl = drilled solids, % by vol x 9.1

Example: Mud weight = 16.0 ppg Chlorides = 73,000 ppm

1. Percent by volume saltwater (SW)

SW = [(5.88 x 10"8)(73,000)1'2 + 1] x 57 SW = [(5.88-8 x 685468.39) + 1] x 57 SW = (0.0403055 + 1) x 57 SW = 59.2974 percent by volume

2. Percent by volume suspended solids (SS)

SS = 100 — 7.5 — 59.2974 SS = 33.2026 percent by volume

3. Average specific gravity of saltwater (ASGsw)

ASGsw = [(73,000) 095 — (1.94 x 10-6)] + 1 ASGsw = (41,701.984 x l.94-6) + 1 ASGsw = 0.0809018 + I ASGsw = 1.0809

4. Average specific gravity of solids (ASG)

ASO = (12 x 16) — (59.2974 x 1.0809) — (0.84 x 7.5)

Retort Analysis:

water oil solids

= 57.0% by volume = 7.5% by volume = 35.5% by volume

33.2026

ASG = 121.60544 33.2026

ASG = 3.6625

  1. Because a high chloride example is being used, Step 5 is omitted.
  2. Percent by volume low gravity solids (LGS)

LGS = 11.154 percent by volume

7. Percent by volume barite

Barite, % by volume = 33.2026 — 11.154 Barite = 22.0486 % by volume

8. Barite, lb/bbl

Barite, lb/bbl = 22.0486 x 14.71 Barite = 324.3349 lb/bbl

9. Bentonite determination a) lb/bbl = 1 _- (1— (7 _- 65) x (30 — 9 x (7 _- 65)) x 11.154 lb/bbl = 1.1206897 x 2.2615385 x 11.154

Bent = 28.26965 lb/bbl b) Bentonite, % by volume

Bent, % by vol = 28.2696 _- 9.1 Bent = 3.10655% by vol

10. Drilled solids, percent by volume

Drilled solids, % by vol = 11.154 — 3.10655 Drilled solids = 8.047% by vol

11. Drilled solids, pounds per barrel

Drilled solids, lb/bbl = 8.047 x 9.1 Drilled solids = 73.2277 lb/bbl

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