Salt solution mining is a sophisticated feat of subsurface geotechnical engineering. It involves creating and managing large, stable underground voids—or caverns—by dissolving salt formations deep within the earth. This process begins by injecting a solvent (typically fresh or undersaturated water) into a targeted salt stratum and extracting the resulting brine. The objectives are twofold: to produce saturated brine for industrial use (e.g., for chlor-alkali plants) or to create vast, secure caverns for the strategic storage of hydrocarbons like natural gas and hydrogen.
This document delves into the critical engineering principles, operational challenges, and geomechanical considerations that define modern solution mining, from well design and integrity to the complex dynamics of cavern development and long-term stability.
The Anatomy of a Solution Mining Well: Engineering for Integrity
A solution mining well is more than just a hole; it is a multi-layered conduit designed to withstand immense subsurface pressures and facilitate controlled fluid exchange for decades.
Concentric Casing Design: The well consists of several nested steel pipes, or “casing strings.”
Surface Casing: The outermost, widest casing is set at a shallow depth and cemented securely in place. Its primary function is to provide structural stability in softer surface layers and, crucially, to isolate and protect shallow freshwater aquifers from the high-pressure, saline environment of the well.
Final Casing (Production Casing): This casing string extends from the surface down to just below the intended cavern roof. It is cemented along its entire length, forming the primary hydraulic seal. This cement job is critical for well integrity, preventing leaks and ensuring that dissolution only occurs in the targeted zone.
Tubing Strings: Inside the final casing, one or more non-cemented “tubing” strings are hung. These are the operational workhorses for injecting solvent and extracting brine. Their depth can be adjusted (“snubbed”) as the cavern evolves.
Managing Subsurface Pressures: The well design must master two fundamental forces:
-
Hydrostatic Pressure: The pressure exerted by the column of groundwater in the formations surrounding the well.
-
Lithostatic Pressure: The immense pressure exerted by the weight of the overlying rock (the overburden). In deep salt formations, this can be tens of megapascals (MPa).
The cemented final casing is engineered to resist these external pressures and the internal operating pressures of the cavern, which are carefully managed to maintain geomechanical stability.
The Dissolution Process: Forging a Cavern with Fluid Dynamics
The shape and growth rate of a cavern are governed by the method of circulation and the fundamental laws of physics and chemistry.
Circulation Methods: Steering the Dissolution
Direct Circulation: The solvent is pumped down the central tubing string, and the resulting brine is extracted up the annular space between the tubing and the final casing.
- Result: Creates a more cylindrical, “pear-shaped” cavern, as the fresh solvent is released at the bottom and rises, dissolving the walls as it moves upward.
Reverse Circulation: The solvent is pumped down the annulus, and brine is extracted through the central tubing from the cavern sump.
- Result: Tends to create a “morning glory” shape—wider at the top than the base—because the lighter solvent immediately rises to the roof upon entering the cavern, concentrating dissolution in the upper sections.
The Physics of Density: Why a Blanket is Essential
The process is fundamentally driven by a density differential, a key parameter in solution mining operations:
- Fresh Water Density: ~$1000 \text{ kg/m}^3$
- Saturated NaCl Brine Density: ~$1200 \text{ kg/m}^3$ (approx. 20% denser)
- Blanket Fluid (e.g., Diesel/LPG/Nitrogen): Significantly less dense than both water and brine.
This density difference causes the injected freshwater to rise buoyantly within the cavern, leading to dissolution rates on the vertical cavern walls and roof that can be 1.5 to 2.0 times faster than on the horizontal floor.
To prevent uncontrolled upward dissolution and the potential collapse of the cavern roof, an inert, low-density blanket fluid is injected. This fluid floats on top of the brine, creating a protective layer that insulates the roof from the solvent. Modern operations favor nitrogen or compressed air over historical hydrocarbon blankets (like diesel) to eliminate environmental risks.
Geotechnical Stability and Operational Management
Creating a cavern is only half the battle; managing its shape, stability, and output is a continuous engineering challenge.
Cavern Monitoring and Shaping
The precise shape, size, and volume of the developing cavern are not left to chance. They are meticulously tracked using sonar logging tools. These instruments are lowered into the cavern to emit acoustic signals and record the echoes, generating a detailed 3D map of the subterranean void. By adjusting the volume of the blanket fluid and switching between circulation methods, operators can actively “steer” the cavern’s shape to meet specific design requirements.
Surface Operations: Power and Precision
Pumping Power: Extracting the dense brine from deep underground is an energy-intensive process. The surface pumps must generate sufficient pressure to overcome both the hydrostatic head of the fluid column and frictional losses in the piping. The required hydraulic horsepower is a direct function of the brine’s high density and the well’s depth. A simplified pressure calculation is:
\[\Delta P \approx \rho_{brine} \cdot g \cdot h\]Where h is the lifting height. This highlights why lifting brine requires significantly more motor power than injecting freshwater.
Brine Concentration Control: For brine production wells, maintaining a near-saturated product is crucial for economic efficiency.
- Dilute brine is costly to process at the surface, as more water must be evaporated to crystallize the salt.
- Supersaturated brine can cause salt to precipitate out within the tubing, leading to clogging and potential well failure. Flow rates are initially kept low to allow the brine to reach saturation and are gradually increased as the cavern’s surface area grows.
Managing Insolubles: The Sump
Most salt formations contain impurities like anhydrite, dolomite, and shale. As the salt dissolves, these insoluble materials fall to the bottom of the cavern, forming a sump. Over time, this pile of debris can grow to be tens of meters thick. To prevent the tubing intake from being buried, it must be periodically raised, an operation known as “snubbing.” If the sump overtakes the tubing or if rockfalls damage the casing, the well may need to be plugged and abandoned.
Long-Term Challenges: Subsidence and Legacy Wells
The long-term legacy of solution mining presents significant geomechanical and environmental challenges.
From “Expected-to-Fail” to Engineered Assets: Historically, many brine wells were operated until they failed from casing corrosion, roof collapse, or subsidence. Modern wells, however, are designed and monitored for lifespans of 30-50 years or more, with well integrity and cavern stability as paramount concerns.
Subsidence Risk: An over-exploited or poorly designed cavern can lead to gradual or catastrophic surface subsidence. The stability of the cavern roof is a function of its span, thickness, depth, and the geomechanical properties of the salt.
Legacy Brinefields: Many areas mined in the 18th and 19th centuries lack proper documentation of well locations and cavern sizes. This creates significant challenges for modern urban planning and makes it difficult to distinguish between anthropogenic sinkholes caused by old well collapses and natural dissolution features (salt karst).
Ultimately, successful solution mining is a masterful blend of geology, fluid mechanics, and structural engineering—a testament to humanity’s ability to shape the deep earth for its needs.
Appendix: Brine Strength and Composition Data
This table provides detailed information on brine properties at various concentrations, showing the relationship between different measurement scales (Salometer, Baume) and the corresponding mass composition of Sodium Chloride (NaCl) and water.
| Salometer Degree | Baume Degree | NaCl (g/L) | Water (g/L) | NaCl % by Water Weight |
|---|---|---|---|---|
| 0.00 | 0.00 | 0.00 | 1000.00 | 0.00 |
| 0.33 | 0.10 | 0.88 | 999.33 | 0.09 |
| 0.67 | 0.20 | 1.77 | 998.67 | 0.18 |
| 1.00 | 0.30 | 2.65 | 998.00 | 0.26 |
| 1.33 | 0.40 | 3.53 | 997.33 | 0.35 |
| 1.67 | 0.50 | 4.42 | 996.67 | 0.44 |
| 2.00 | 0.60 | 5.30 | 996.00 | 0.53 |
| 2.40 | 0.70 | 6.36 | 995.83 | 0.63 |
| 2.80 | 0.80 | 7.42 | 995.67 | 0.74 |
| 3.20 | 0.90 | 8.48 | 995.50 | 0.84 |
| 3.60 | 1.00 | 9.54 | 995.33 | 0.95 |
| 4.00 | 1.10 | 10.60 | 995.00 | 1.05 |
| 4.40 | 1.20 | 11.68 | 994.60 | 1.16 |
| 4.80 | 1.30 | 12.76 | 994.20 | 1.27 |
| 5.20 | 1.40 | 13.84 | 993.80 | 1.37 |
| 5.60 | 1.50 | 14.92 | 993.40 | 1.48 |
| 6.00 | 1.60 | 16.00 | 993.00 | 1.59 |
| 6.40 | 1.70 | 17.08 | 992.60 | 1.69 |
| 6.80 | 1.80 | 18.16 | 992.20 | 1.80 |
| 7.20 | 1.90 | 19.24 | 991.80 | 1.90 |
| 7.60 | 2.00 | 20.32 | 991.40 | 2.01 |
| 8.00 | 2.10 | 21.40 | 991.00 | 2.11 |
| 8.33 | 2.20 | 22.30 | 990.83 | 2.20 |
| 8.67 | 2.30 | 23.20 | 990.67 | 2.29 |
| 9.00 | 2.40 | 24.10 | 990.50 | 2.38 |
| 9.33 | 2.50 | 25.00 | 990.33 | 2.46 |
| 9.67 | 2.60 | 25.90 | 990.17 | 2.55 |
| 10.00 | 2.70 | 26.80 | 990.00 | 2.64 |
| 10.33 | 2.80 | 27.72 | 989.67 | 2.72 |
| 10.67 | 2.90 | 28.63 | 989.33 | 2.81 |
| 11.00 | 3.00 | 29.55 | 989.00 | 2.90 |
| 11.33 | 3.10 | 30.47 | 988.67 | 2.99 |
| 11.67 | 3.20 | 31.38 | 988.33 | 3.08 |
| 12.00 | 3.30 | 32.30 | 988.00 | 3.17 |
| 12.50 | 3.40 | 33.70 | 987.50 | 3.30 |
| 13.00 | 3.50 | 35.10 | 987.00 | 3.43 |
| 13.50 | 3.60 | 36.50 | 986.50 | 3.57 |
| 14.00 | 3.70 | 37.90 | 986.00 | 3.70 |
| 14.40 | 3.80 | 39.00 | 985.80 | 3.81 |
| 14.80 | 3.90 | 40.10 | 985.60 | 3.91 |
| 15.20 | 4.00 | 41.20 | 985.40 | 4.01 |
| 15.60 | 4.10 | 42.30 | 985.20 | 4.12 |
| 16.00 | 4.20 | 43.40 | 985.00 | 4.22 |
| 16.33 | 4.30 | 44.33 | 984.67 | 4.31 |
| 16.67 | 4.40 | 45.27 | 984.33 | 4.40 |
| 17.00 | 4.50 | 46.20 | 984.00 | 4.48 |
| 17.33 | 4.60 | 47.13 | 983.67 | 4.57 |
| 17.67 | 4.70 | 48.07 | 983.33 | 4.66 |
| 18.00 | 4.80 | 49.00 | 983.00 | 4.75 |
| 18.40 | 4.90 | 50.12 | 982.60 | 4.85 |
| 18.80 | 5.00 | 51.24 | 982.20 | 4.96 |
| 19.20 | 5.10 | 52.36 | 981.80 | 5.06 |
| 19.60 | 5.20 | 53.48 | 981.40 | 5.17 |
| 20.00 | 5.30 | 54.60 | 981.00 | 5.27 |
| 20.40 | 5.40 | 55.74 | 980.60 | 5.38 |
| 20.80 | 5.50 | 56.88 | 980.20 | 5.48 |
| 21.20 | 5.60 | 58.02 | 979.80 | 5.59 |
| 21.60 | 5.70 | 59.16 | 979.40 | 5.70 |
| 22.00 | 5.80 | 60.30 | 979.00 | 5.80 |
| 22.33 | 5.90 | 61.27 | 978.67 | 5.89 |
| 22.67 | 6.00 | 62.23 | 978.33 | 5.98 |
| 23.00 | 6.10 | 63.20 | 978.00 | 6.07 |
| 23.33 | 6.20 | 64.17 | 977.67 | 6.16 |
| 23.67 | 6.30 | 65.13 | 977.33 | 6.25 |
| 24.00 | 6.40 | 66.10 | 977.00 | 6.34 |
| 24.40 | 6.50 | 67.26 | 976.80 | 6.44 |
| 24.80 | 6.60 | 68.42 | 976.60 | 6.55 |
| 25.20 | 6.70 | 69.58 | 976.40 | 6.65 |
| 25.60 | 6.80 | 70.74 | 976.20 | 6.76 |
| 26.00 | 6.90 | 71.90 | 976.00 | 6.86 |
| 26.40 | 7.00 | 73.06 | 975.60 | 6.97 |
| 26.80 | 7.10 | 74.22 | 975.20 | 7.07 |
| 27.20 | 7.20 | 75.38 | 974.80 | 7.18 |
| 27.60 | 7.30 | 76.54 | 974.40 | 7.28 |
| 28.00 | 7.40 | 77.70 | 974.00 | 7.39 |
| 28.40 | 7.50 | 78.88 | 973.60 | 7.49 |
| 28.80 | 7.60 | 80.06 | 973.20 | 7.60 |
| 29.20 | 7.70 | 81.24 | 972.80 | 7.71 |
| 29.60 | 7.80 | 82.42 | 972.40 | 7.81 |
| 30.00 | 7.90 | 83.60 | 972.00 | 7.92 |
| 30.33 | 8.00 | 84.58 | 971.67 | 8.01 |
| 30.67 | 8.10 | 85.57 | 971.33 | 8.10 |
| 31.00 | 8.20 | 86.55 | 971.00 | 8.18 |
| 31.33 | 8.30 | 87.53 | 970.67 | 8.27 |
| 31.67 | 8.40 | 88.52 | 970.33 | 8.36 |
| 32.00 | 8.50 | 89.50 | 970.00 | 8.45 |
| 32.40 | 8.60 | 90.68 | 969.60 | 8.55 |
| 32.80 | 8.70 | 91.86 | 969.20 | 8.66 |
| 33.20 | 8.80 | 93.04 | 968.80 | 8.76 |
| 33.60 | 8.90 | 94.22 | 968.40 | 8.87 |
| 34.00 | 9.00 | 95.40 | 968.00 | 8.97 |
| 34.40 | 9.10 | 96.60 | 967.60 | 9.08 |
| 34.80 | 9.20 | 97.80 | 967.20 | 9.18 |
| 35.20 | 9.30 | 99.00 | 966.80 | 9.29 |
| 35.60 | 9.40 | 100.20 | 966.40 | 9.39 |
| 36.00 | 9.50 | 101.40 | 966.00 | 9.50 |
| 36.40 | 9.60 | 102.62 | 965.60 | 9.61 |
| 36.80 | 9.70 | 103.84 | 965.20 | 9.71 |
| 37.20 | 9.80 | 105.06 | 964.80 | 9.82 |
| 37.60 | 9.90 | 106.28 | 964.40 | 9.93 |
| 38.00 | 10.00 | 107.50 | 964.00 | 10.03 |
| 38.40 | 10.10 | 108.70 | 963.60 | 10.14 |
| 38.80 | 10.20 | 109.90 | 963.20 | 10.24 |
| 39.20 | 10.30 | 111.10 | 962.80 | 10.35 |
| 39.60 | 10.40 | 112.30 | 962.40 | 10.45 |
| 40.00 | 10.50 | 113.50 | 962.00 | 10.55 |
| 40.40 | 10.60 | 114.72 | 961.60 | 10.66 |
| 40.80 | 10.70 | 115.94 | 961.20 | 10.76 |
| 41.20 | 10.80 | 117.16 | 960.80 | 10.87 |
| 41.60 | 10.90 | 118.38 | 960.40 | 10.97 |
| 42.00 | 11.00 | 119.60 | 960.00 | 11.08 |
| 42.40 | 11.10 | 120.84 | 959.40 | 11.19 |
| 42.80 | 11.20 | 122.08 | 958.80 | 11.29 |
| 43.20 | 11.30 | 123.32 | 958.20 | 11.40 |
| 43.60 | 11.40 | 124.56 | 957.60 | 11.51 |
| 44.00 | 11.50 | 125.80 | 957.00 | 11.62 |
| 44.40 | 11.60 | 127.04 | 956.60 | 11.72 |
| 44.80 | 11.70 | 128.28 | 956.20 | 11.83 |
| 45.20 | 11.80 | 129.52 | 955.80 | 11.93 |
| 45.60 | 11.90 | 130.76 | 955.40 | 12.04 |
| 46.00 | 12.00 | 132.00 | 955.00 | 12.14 |
| 46.40 | 12.10 | 133.24 | 954.60 | 12.25 |
| 46.80 | 12.20 | 134.48 | 954.20 | 12.35 |
| 47.20 | 12.30 | 135.72 | 953.80 | 12.46 |
| 47.60 | 12.40 | 136.96 | 953.40 | 12.56 |
| 48.00 | 12.50 | 138.20 | 953.00 | 12.66 |
| 48.50 | 12.60 | 139.78 | 952.50 | 12.80 |
| 49.00 | 12.70 | 141.35 | 952.00 | 12.93 |
| 49.50 | 12.80 | 142.93 | 951.50 | 13.06 |
| 50.00 | 12.90 | 144.50 | 951.00 | 13.19 |
| 50.40 | 13.00 | 145.78 | 950.60 | 13.30 |
| 50.80 | 13.10 | 147.06 | 950.20 | 13.40 |
| 51.20 | 13.20 | 148.34 | 949.80 | 13.51 |
| 51.60 | 13.30 | 149.62 | 949.40 | 13.61 |
| 52.00 | 13.40 | 150.90 | 949.00 | 13.72 |
| 52.40 | 13.50 | 152.16 | 948.40 | 13.83 |
| 52.80 | 13.60 | 153.42 | 947.80 | 13.93 |
| 53.20 | 13.70 | 154.68 | 947.20 | 14.04 |
| 53.60 | 13.80 | 155.94 | 946.60 | 14.14 |
| 54.00 | 13.90 | 157.20 | 946.00 | 14.25 |
| 54.40 | 14.00 | 158.50 | 945.60 | 14.36 |
| 54.80 | 14.10 | 159.80 | 945.20 | 14.46 |
| 55.20 | 14.20 | 161.10 | 944.80 | 14.57 |
| 55.60 | 14.30 | 162.40 | 944.40 | 14.67 |
| 56.00 | 14.40 | 163.70 | 944.00 | 14.78 |
| 56.50 | 14.50 | 165.30 | 943.25 | 14.91 |
| 57.00 | 14.60 | 166.90 | 942.50 | 15.04 |
| 57.50 | 14.70 | 168.50 | 941.75 | 15.18 |
| 58.00 | 14.80 | 170.10 | 941.00 | 15.31 |
| 58.40 | 14.90 | 171.42 | 940.60 | 15.42 |
| 58.80 | 15.00 | 172.74 | 940.20 | 15.52 |
| 59.20 | 15.10 | 174.06 | 939.80 | 15.63 |
| 59.60 | 15.20 | 175.38 | 939.40 | 15.73 |
| 60.00 | 15.30 | 176.70 | 939.00 | 15.84 |
| 60.40 | 15.40 | 178.00 | 938.40 | 15.94 |
| 60.80 | 15.50 | 179.30 | 937.80 | 16.05 |
| 61.20 | 15.60 | 180.60 | 937.20 | 16.16 |
| 61.60 | 15.70 | 181.90 | 936.60 | 16.26 |
| 62.00 | 15.80 | 183.20 | 936.00 | 16.37 |
| 62.50 | 15.90 | 184.85 | 935.50 | 16.50 |
| 63.00 | 16.00 | 186.50 | 935.00 | 16.63 |
| 63.50 | 16.10 | 188.15 | 934.50 | 16.76 |
| 64.00 | 16.20 | 189.80 | 934.00 | 16.89 |
| 64.40 | 16.30 | 191.14 | 933.60 | 16.99 |
| 64.80 | 16.40 | 192.48 | 933.20 | 17.10 |
| 65.20 | 16.50 | 193.82 | 932.80 | 17.20 |
| 65.60 | 16.60 | 195.16 | 932.40 | 17.31 |
| 66.00 | 16.70 | 196.50 | 932.00 | 17.41 |
| 66.40 | 16.80 | 197.94 | 931.40 | 17.53 |
| 66.80 | 16.90 | 199.38 | 930.80 | 17.64 |
| 67.20 | 17.00 | 200.82 | 930.20 | 17.76 |
| 67.60 | 17.10 | 202.26 | 929.60 | 17.87 |
| 68.00 | 17.20 | 203.70 | 929.00 | 17.98 |
| 68.40 | 17.30 | 204.96 | 928.40 | 18.08 |
| 68.80 | 17.40 | 206.22 | 927.80 | 18.18 |
| 69.20 | 17.50 | 207.48 | 927.20 | 18.29 |
| 69.60 | 17.60 | 208.74 | 926.60 | 18.39 |
| 70.00 | 17.70 | 210.00 | 926.00 | 18.49 |
| 70.50 | 17.80 | 211.68 | 925.50 | 18.61 |
| 71.00 | 17.90 | 213.35 | 925.00 | 18.74 |
| 71.50 | 18.00 | 215.03 | 924.50 | 18.87 |
| 72.00 | 18.10 | 216.70 | 924.00 | 19.00 |
| 72.40 | 18.20 | 218.06 | 923.40 | 19.10 |
| 72.80 | 18.30 | 219.42 | 922.80 | 19.21 |
| 73.20 | 18.40 | 220.78 | 922.20 | 19.32 |
| 73.60 | 18.50 | 222.14 | 921.60 | 19.42 |
| 74.00 | 18.60 | 223.50 | 921.00 | 19.53 |
| 74.40 | 18.70 | 224.92 | 920.40 | 19.64 |
| 74.80 | 18.80 | 226.34 | 919.80 | 19.75 |
| 75.20 | 18.90 | 227.76 | 919.20 | 19.86 |
| 75.60 | 19.00 | 229.18 | 918.60 | 19.97 |
| 76.00 | 19.10 | 230.60 | 918.00 | 20.08 |
| 76.40 | 19.20 | 231.96 | 917.60 | 20.18 |
| 76.80 | 19.30 | 233.32 | 917.20 | 20.28 |
| 77.20 | 19.40 | 234.68 | 916.80 | 20.38 |
| 77.60 | 19.50 | 236.04 | 916.40 | 20.48 |
| 78.00 | 19.60 | 237.40 | 916.00 | 20.58 |
| 78.50 | 19.70 | 239.15 | 915.25 | 20.72 |
| 79.00 | 19.80 | 240.90 | 914.50 | 20.85 |
| 79.50 | 19.90 | 242.65 | 913.75 | 20.98 |
| 80.00 | 20.00 | 244.40 | 913.00 | 21.12 |
| 80.50 | 20.10 | 246.18 | 912.50 | 21.25 |
| 81.00 | 20.20 | 247.95 | 912.00 | 21.38 |
| 81.50 | 20.30 | 250.32 | 911.50 | 21.55 |
| 82.00 | 20.40 | 251.50 | 911.00 | 21.63 |
| 82.33 | 20.50 | 252.67 | 910.50 | 21.72 |
| 82.67 | 20.60 | 253.83 | 910.00 | 21.81 |
| 83.00 | 20.70 | 255.00 | 909.50 | 21.90 |
| 83.33 | 20.80 | 256.17 | 909.00 | 21.99 |
| 83.67 | 20.90 | 257.33 | 908.50 | 22.07 |
| 84.00 | 21.00 | 258.50 | 908.00 | 22.16 |
| 84.50 | 21.10 | 260.30 | 908.75 | 22.27 |
| 85.00 | 21.20 | 262.10 | 909.50 | 22.37 |
| 85.50 | 21.30 | 263.90 | 910.25 | 22.48 |
| 86.00 | 21.40 | 265.70 | 905.00 | 22.70 |
| 86.40 | 21.50 | 267.14 | 904.40 | 22.80 |
| 86.80 | 21.60 | 268.58 | 903.72 | 22.91 |
| 87.20 | 21.70 | 270.02 | 902.78 | 23.02 |
| 87.60 | 21.80 | 271.46 | 901.42 | 23.14 |
| 88.00 | 21.90 | 272.90 | 902.00 | 23.23 |
| 88.30 | 22.00 | 274.10 | 901.00 | 23.33 |
| 88.87 | 22.10 | 276.10 | 900.33 | 23.47 |
| 89.43 | 22.20 | 278.10 | 899.67 | 23.61 |
| 90.00 | 22.30 | 280.10 | 899.00 | 23.76 |
| 90.50 | 22.40 | 281.93 | 898.25 | 23.89 |
| 91.00 | 22.50 | 283.75 | 897.50 | 24.02 |
| 91.50 | 22.60 | 285.58 | 896.75 | 24.15 |
| 92.00 | 22.70 | 287.40 | 896.00 | 24.29 |
| 92.33 | 22.80 | 288.62 | 895.50 | 24.37 |
| 92.67 | 22.90 | 289.83 | 895.00 | 24.46 |
| 93.00 | 23.00 | 291.05 | 894.50 | 24.55 |
| 93.33 | 23.10 | 292.27 | 894.00 | 24.64 |
| 93.67 | 23.20 | 293.48 | 893.50 | 24.73 |
| 94.00 | 23.30 | 294.70 | 893.00 | 24.81 |
| 94.50 | 23.40 | 298.40 | 892.50 | 25.06 |
| 95.00 | 23.50 | 298.40 | 892.00 | 25.07 |
| 95.50 | 23.60 | 300.25 | 891.00 | 25.20 |
| 96.00 | 23.70 | 302.10 | 890.00 | 25.34 |
| 96.50 | 23.80 | 303.59 | 889.00 | 25.46 |
| 97.00 | 23.90 | 305.08 | 888.00 | 25.57 |
| 97.33 | 24.00 | 306.59 | 887.67 | 25.67 |
| 97.67 | 24.10 | 308.09 | 887.28 | 25.77 |
| 98.00 | 24.20 | 309.60 | 887.00 | 25.87 |
| 98.50 | 24.30 | 311.50 | 886.50 | 26.00 |
| 99.00 | 24.40 | 313.40 | 886.00 | 26.13 |
| 99.60 | 24.50 | 315.60 | 885.00 | 26.29 |
| 100.00 | 24.60 | 317.20 | 884.00 | 26.41 |