Fluid Saturation Methods

RETORT METHOD AT ATMOSPHERIC

PRESSURE

Fluid Saturation Methods

Apparatus

• Core holder assembly
• Solvent delivery device
• Related hardware
• Analytical balances
• Syringes
• Materials and reagents

Thanks

Accuracy

This technique is ± 0.05 percent

Precision

Accuracy-Precision

Advantages

Not differ by more than ±0.3 percent.

Proper distillation and drying techniques should permit oil

and water content determination to within 2 %

Limitations

• All measurements can be made on the same sample.
• Solid organics are not represented in oil volumes.
• Accurate grain densities can be measured

Advantages & Limitations

• Oil volumes are sensitive to drying techniques.
• Long extraction times are needed due to the low permeability of this type of rock material.
• Sample loss is critical in determination of oil content

Karl Fischer Titration

Advantages

Accuracy/Precision

• All the water phase is retained within the core during retrieval.
• In situ saturation may not be qualitatively determined.
• Tritiated water is the recommended drilling fluid filtrate
• tracer.

Limitations

The precision of the measurements of the extent of drilling

fluid filtrate invasion into the core is within about 5 to 20 percent.

Limitations

Procedures & Precautions

• Large volumes of sample can be used.
• The method is fairly rapid.
• All measurements are made directly and independently of others.
• Standard retorting equipment and procedures can be used.

Calculations

• Have a tendency to oxidize using the technique described here.
• Moisture content results will be too low if oxidation occurs.
• Oxidation adds weight and will cause the dry weight to be too high

• Oil yields may be dependent on rate of heating.
• Due to emulsions, there may be difficulty in reading the meniscus in the collection glassware.

• Use established safety procedures.
• Care should be taken to avoid evaporation of water.
• The selected full diameter core intervals should be faced into right cylinders.
• The plug and donut samples are weighed.
• The samples are dried in a convection oven.
• Porosity is determined and Water saturation is calculated.
• The amount of drilling fluid filtrate.

Core plug samples are cleaned by dynamic miscible displacement

Apparatus

Calculations should be performed as stipulated in 4.3.1.4

Procedures-Precautions

Procedures/Precautions

• Drill press
• Distillation extraction apparatus
• Drilling fluid filter press for extraction

Apparatus

Precaution

OIL SHALES

If samples are to be crushed to expedite hydrocarbon removal or grain volume determinations, then bulk volumes should be measured and samples weighed prior to crushing.

Do not over-dry the coal sample. Oxidation of the coal

occurs if it dries too long in air.

• No attempt is made to screen the crushed.
• An adjacent sample is not prepared for the mercury pump tests.
• Oil coking and cracking losses are ignored.
• The oven is allowed to heat at a rate consistent.

The apparatus is the same as used for the Retort Method at

Atmospheric Pressure

Procedures

Oil shale is defined as rock composed of clay to silt size particles containing various quantities of solid organic material

The procedures are the same as in 4.3.1.3

Filtrate Invasion Analysis

(Pressure Cores)

Advantages

Limitations

Productive Shale

• Sampling
• Crushing
• Sample Size

• Weighing
• Drying Pan
• Sample Initial Weight
• Dry Weight Measurements

Limitations

• Larger, more costly equipment is required
• Laboratory space requirements are greater.
• Longer distillation and core cleaning times are required
• Large volumes of solvents are used thereby requiring a higher investment in same

SOLVENT FLUSHING

• A high precision analytical balance
• Grain loss during the handling and testing procedures is not as critical
• Collected water volumes are quite large

• Techniques is that they can determine saturations in cores only if they are saturated with tagged fluids.
• NMR technique is the inability to handle cores containing significant ferromagnetic materials, clays, or gas.

The objective of filtrate invasion analysis is to quantify the

amount of drilling fluid filtrate that invades the core during

the coring operation.

Procedures

Apparatus

measuring fluid saturations of the pore space

Advantages

Apparatus

• The procedures are the same as those for plug sampleswith the exception that sample weights should be made to the nearest 0.1 gram.
• Also, the cleaning time of 48 hours may have to be extended in order to fully clean the larger volume samples.
• Longer times and supplemental cleaning are frequently required.

• An important advantage of these methods is their ability to provide information.
• Another advantage of these techniques is that the measurements are made noninvasively and nondestructively.
• Saturations can be monitored without terminating a laboratory experiment.
• An advantage of the microwave and NMR techniques is their capability to determine water saturation

• Flask
• Trap
• Extraction core protector

• Crusher
• Drying pans
• Drying oven
• Balance
• No. 8 Sieve
• Glass desiccator

Procedures/Precautions

Full Diameter Cores

Refer to the Bibliography for the many procedures and precautions for the

individual techniques.

COAL ANALYSIS

DISTILLATION EXTRACTION METHOD (DEAN

STARK)

Accuracy & Precision

Advantages

procedures as those for plug samples

Apparatus

• the oil value obtained is within ±5%
• The accuracy of the water volumes is ±2.5% of measured volumes.

• The analytical process is rapid and provides required saturation data within hours.
• Grain loss does not affect the fluid saturation data.

Calculations

Limitations

WS = (WB x 100)/(GB + OB + WB)

Where:

Procedures & Precautions

• Water saturation (and porosity) may be too high.
• Oil saturation (and porosity) may be too high
• Oil volume correction curves are required
• The distilled liquids may form emulsions.

WS = water saturation as a percentage of pore volume.

With coal, the fluid of primary concern is water. Water

saturation, or more appropriately, moisture content is a fundamental

property of coal.

WB = water saturation as a percentage of bulk volume

GB = gas saturation as a percentage of bulk volume.

OB = oil saturation as a percentage of bulk volume.

• Typical analyses are done on a foot-by-foot basis.
• This sample is broken lengthwise into two halves. One half is designated for the fluid saturation sample and the other half is used to obtain a plug for the determination of permeability and/or Boyle’s Law porosity.
• the sample should be well rounded to permit mercury conformance. The weight of the sample is recorded and the bulk volume of this sample is determined by mercury displacement.
• The sample for the water and oil measurement should be crushed into approximately 1/4-inch.
• The oven temperature initially maintained at 350°F (177°C).
• when all samples cease to give off fluids the process is considered complete.

• X-ray and CT equipment
• Microwave and gamma-ray absorption apparatu.

Apparatus

Principles of Analysis

• Stainless steel retort
• Oven
• Water bath
• Calibrated glass receiving tube
• Rock hammer and crusher
• Diamond saw
• Mercury pump
• Centrifuge

Oil and water fluid saturations are obtained by a high-temperature retorting process in which the oil and water contained in a fresh sample of crushed core material are

vaporized, condensed, and collected in calibrated glassware

• Water saturation (and porosity) may be too high

Plug Samples

This procedure is appropriate for plug samples and for rotary sidewall cores.

SCANNING METHODS

Apparatus

Procedures

• Stainless steel retorts
• Oven
• Calibrated glass receiving tubes
• Mercury pump
• An apparatus capable of piercing the jar lid is optional
• A hot wire gas detector
• A gas chromatograph is optional

Procedures

Principles of Analysis

Apparatus and Reagents

Pressure-Retained

Core Analysis

• The sample is weighed
• An alternating methanol-toluene solvent injection
• All storage vials, syringes, or collection vessels should be weighed or tared prior to use.
• A glass vial is filled with the initial injectant reagent and sealed.
• Step d is repeated using the alternating solvent.
• Step d is repeated using the initial solvent.
• The storage vials and vessels are reweighed
• analyzed for water content by Karl Fischer.

• Samples should be received in the laboratory sealed in glass jars with screw-top lids.
• The samples should be arranged in descending depth order.
• The sample recovery (sample length)
• Each sample is then removed from the jar and is cleaned of drilling fluid solids.
• A brief description of the sample is recorded
• The sample is placed in the cell of a precalibrated mercury pump, and bulk volume is determined by mercury displacement.

Measure the absorption of high energy electromagnetic radiation by fluids that have been tagged with high absorption agents.

Precautions

Smaller samples are involved in the sidewall procedure and therefore the equipment is scaled down to provide comparable accuracy.

• Flask
• Trap
• Condenser
• Desiccant holder
• Extraction thimbles
• Extraction cup
• Drying oven
• Boiling chips
• Solvent

The objective of pressure retained core analysis is to provide fluid saturation data on cores for which fluid.

Accuracy & Precision

• so exposure time to room conditions should be minimized.
• Since handling mercury is required with this fluid saturation method all existing safety and health standards should be followed.
• Consult relevant environmental regulations and local laws.

Limitations

Advantages

The method’s accuracy is strongly dependent on sample size, especially when determining oil volumes

Calculations

• The distilled liquids may form emulsions
• Volumes of oil <0.1 ml are difficult to determine accurately.
• minimize loss of liquids, especially water.
• Porosity and fluid saturation values can be in error if gypsum or hydratable clays

Tar (Oil) Sand Analysis

WS = (WB x 100)/(GB + OB + WB)

• Gas, oil, and water measurements are made using one sample.
• The method is relatively rapid.
• This is a “direct” measurement method where gas, oil, and water measurements are made independently.

Precautions

Where:

Percussion Sidewall Cores

WS = water saturation as a percentage of pore volume.

WB = water saturation as a percentage of bulk volume.

GB = gas saturation as a percentage of bulk volume.

OB = oil saturation as a percentage of bulk volume

Procedures

• Material safety data sheets should be consulted.
• Methanol is highly susceptible to water absorption from atmospheric humidity.
• The Karl Fischer titration requires only a small amount of solvent; therefore.

Calculations

Precautions

• The samples are prepared using a fluid that is compatiblewith the fluid used to cut the whole core or drilled sidewall cores in the well.
• The excess fluid remaining on the sample after the trimming of the ends should be wiped off.
• should be stored in a container to prevent evaporation until they are placed in the apparatus.
• The distillation/extraction process continues for a minimum of 48 hours.

Apparatus

• Oil may contain compounds exhibiting carcinogenic properties It may be flammable.
• Toluene is moderately toxic.
• Many other solvents, while effective for the oil removal process, may be dangerous and toxic.
• should be aware of the change in solvent boiling.

Advantages

Principles of Analysis

• Water volume determinations are generally very accurate.
• Typically, the sample is not damaged and can be used for further testing.
• Relatively low temperatures.
• The procedure is simple and requires little attention during distillation.

Limitations

Advantages

Determine the fluid saturations of unconsolidated tar (oil) sands

• Inaccuracies arise in the water determination
• Oil volumes are not found directly and may be inaccurate.
• Rock wettability may be altered.
• The clay fabric may be altered, that may result in inaccurate permeability measurements

• Core storage boxes
• Dry ice
• Liquid nitrogen
• Milling machine
• Two-liter dewar flask
• Drilling fluid or low invasion gel removal tools
• Gas collection cells
• Gas collection cylinders
• Centrifuge,Heat lamp.

• All saturation levels can be determined.
• The Karl Fischer titration is very precise.
• Damage to sensitive minerals is minimized
• The procedure removes salts from the sample.

Procedures

Limitations

• Accuracy of the method is dependent on solvent.
• The technique is more complex and expensive.
• Oil saturations are determined indirectly.

Accuracy/Precision

• Core Preparation Procedures
• Gas Collection Procedures
• Distillation Extraction (Dean-Stark) Procedures
• Gas-Driven Solvent Extraction andSaturation

Precision of automated Karl Fischer titration units is ±0.5

percent of the measured value

Apparatus

Procedures-Precautions

The same basic equipment as described in 4.3.1.2 may be

used in this procedure.

Calculations

• may be frozen prior to obtaining a sample.
• The sample is then placed in the distillation extraction apparatus
• Avoid violent boiling by supplying a minimum heat rate to boil the solvent.

The liquid contents of the sample are usually reported as weight percent as opposed to percent pore volume.

Calculations

Advantages-Limitations

• The liquid content values are determined on one sample.
• The method is fairly rapid.
• The calculations are not complex.
• If the sample has a high tar (oil) content, it may be necessary to stop the distillation process so that the dirty toluene in the boiling flask can be replaced with clean toluene.

Accuracy/Precision

• fluid volumes are ±0.5 ml
• oil volume is ±0.1 g or ±0.1 ml.

• Is an expensive, meticulous, and time-consuming operation.
• Pressure-retained core analysis provides fluid saturations more indicative.
• Minimizing pore space flushing during coring
• The ability to capture oil and water in the core provides a distinct advantage over conventional and sponge core analysis.

Accuracy-Precision

The weight percent values should be reported to the nearest

0.1 %