Rise in core wettability characterization method
First Claim
1. A method for determining Reservoir Rock wettability comprising steps of:
- generating and utilizing core samples, wherein a core sample is generated by dividing a core plug into a plurality of core samples of a preset size and wherein the preset size of each core sample in the plurality of core samples is an average diameter of 3.8 cm and a length of 1.5 cm;
sealing a side of the core sample with an epoxy resin, wherein the side of the core sample is sealed to ensure a one-dimensional liquid penetration into the core sample;
mounting a hook on a top side of the core sample;
saturating the core sample with a first reservoir fluid;
connecting the saturated core sample to a high precision balance, wherein the saturated core sample is connected using a thin rope;
taking a second reservoir fluid in an imbibition beaker;
hanging the saturated core sample over the second reservoir fluid contained in the imbibition beaker, wherein the saturated core sample is hanged using a thread and wherein the saturated core sample is hanged in a way such that a bottom part of the saturated core sample barely touches the second reservoir fluid;
commencing an imbibition process for the hanged and saturated core sample;
monitoring a change in a mass of the hanged and saturated core sample over a period of time as imbibitions taking place to obtain a data and wherein the data is a square of the change in the mass of the hanged and saturated core sample over a period of time;
generating a curve using the obtained data by plotting a square of the change in the mass of the hanged and saturated core sample with respect to time;
calculating a slope of the generated curve;
computing a value of a rock constant for the core sample; and
applying the calculated slope of the generated curve and the computed value of a rock constant for the core sample in a modified form of Washburn equation to compute a value of a contact angle;
wherein the computed value of contact angle represents a wettability of the core sample and in turn represents the wettability of a reservoir rock from which the core plug is generated.
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Abstract
The various embodiments herein provide a method for determining core wettability characteristics of reservoir rock samples based on modified form of Washburn equation. The method involves saturating a core sample with a first reservoir fluid such as water and imbibing with a second reservoir fluid such as oil. The change in square of the core mass with respect to time is monitored during an imbibition process to acquire a data to calculate a contact angle to determine the wettability of the sample. The contact angle is calculated by using the modified form of Washburn equation. A single or twin core sample is used to calculate the wettability characteristics. The method measures wettability characteristics in terms of contact angle and not in terms of wettability index.
24 Citations
15 Claims
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1. A method for determining Reservoir Rock wettability comprising steps of:
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generating and utilizing core samples, wherein a core sample is generated by dividing a core plug into a plurality of core samples of a preset size and wherein the preset size of each core sample in the plurality of core samples is an average diameter of 3.8 cm and a length of 1.5 cm; sealing a side of the core sample with an epoxy resin, wherein the side of the core sample is sealed to ensure a one-dimensional liquid penetration into the core sample; mounting a hook on a top side of the core sample; saturating the core sample with a first reservoir fluid; connecting the saturated core sample to a high precision balance, wherein the saturated core sample is connected using a thin rope; taking a second reservoir fluid in an imbibition beaker; hanging the saturated core sample over the second reservoir fluid contained in the imbibition beaker, wherein the saturated core sample is hanged using a thread and wherein the saturated core sample is hanged in a way such that a bottom part of the saturated core sample barely touches the second reservoir fluid; commencing an imbibition process for the hanged and saturated core sample; monitoring a change in a mass of the hanged and saturated core sample over a period of time as imbibitions taking place to obtain a data and wherein the data is a square of the change in the mass of the hanged and saturated core sample over a period of time; generating a curve using the obtained data by plotting a square of the change in the mass of the hanged and saturated core sample with respect to time; calculating a slope of the generated curve; computing a value of a rock constant for the core sample; and applying the calculated slope of the generated curve and the computed value of a rock constant for the core sample in a modified form of Washburn equation to compute a value of a contact angle; wherein the computed value of contact angle represents a wettability of the core sample and in turn represents the wettability of a reservoir rock from which the core plug is generated. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method for determining wettability characteristics of reservoir core samples comprising steps of:
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starting with a preserved core plug; generating a first twin core sample and a second twin core sample, and wherein the generated first twin core sample is used to determine a constant of a modified Washburn equation, and wherein the generated second twin core sample is used to determine wettability of a rock; cleaning the generated first twin core sample; drying the cleaned first twin core sample; saturating the dried first twin core sample with air; imbibing the air saturated first twin core sample with a low energy fluid, wherein the low energy fluid is Dodecane; monitoring a change in a mass of the first twin core sample with respect to time as dodecane imbibes into the first twin core sample; generating a curve by plotting a square of the change in the mass of the first twin core sample with respect to time; determining a slope value of the generated curve; calculating a value of a rock constant by applying the determined slope value of the generated curve and a contact angle of the first twin core sample for the reference fluid in a modified Washburn Equation, wherein the applied contact value of the first twin core sample for the reference fluid is equal to zero as the reference fluid is a dodecane and the dodecane wets the first twin core sample completely; saturating the second twin core sample with a first reservoir fluid, wherein the second twin core sample is saturated in the first reservoir fluid completely; imbibing the saturated second twin core sample with a second reservoir fluid; monitoring a change in a core mass of the second twin core sample with respect to time as the second reservoir fluid is imbibed into the second twin core sample; calculating a square of the change in the mass of the second twin core sample with respect to time; generating a curve for the second twin core sample by plotting the calculated square of the change in the mass of the second twin core sample with respect to time; calculating a slope of the generated curve for the second twin core sample; calculating a value of contact angle by applying the calculated slope of the generated curve for the second twin core sample and the computed value of a rock constant for the first twin core sample in a modified form of Washburn equation; and wherein the calculated value of contact angle represents a wettability of the second twin core sample and in turn corresponds to a wettability of a reservoir rock from which the core plug is extracted. - View Dependent Claims (9, 10, 11, 12, 13, 14, 15)
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Specification