TY - THES

T1 - Low Salinity Water Flooding by Spontaneous Imbibition

AU - Hamad, Walid

N1 - no embargo

PY - 2019

Y1 - 2019

N2 - Low salinity water injection (LSWI) became lately one of the most desirable enhanced oil recovery (EOR) and improved oil recovery (IOR) methods since it is considered a low cost, flexible method and environmentally friendly. The increased interest in this method encouraged the researchers to conduct different tests and experiments in different lithologies to explain the mechanism(s) behind it, and then many field pilots to study the compatibility and profitability of LSWI method. Up to now, it is difficult to build a concrete statement about LSWI mechanism and hence in which reservoir it is applicable. The present thesis tries to study the behavior of LSW spontaneous imbibition (LSW SI) in sandstone outcrops plugs, Bentheim sandstone, using Amott test. The work contains plugs preparing, starting from drilling and preserving them until the restoration process starts. The restoration stage aims to establish a favorable reservoir wettability condition, a mixed wet or weak water-wet state. Restoration process contains cleaning process, drying process, saturating the plugs with connate water, with different concentrations and compositions, drain them with crude oil, and aging them at ambient pressure and reservoir temperature. The plugs were divided into four groups; each of them was aged for a certain time. After the end of the preparation period, the test was conducted by placing the plugs in Amott cells and immersing them with imbibed water with different concentrations and compositions. The result was obtained regularly by reading the cumulative oil production. Different scenarios were planned for the test among them using one composition/one concentration during the test or changing the water salinity and/or composition during the test. The results were analyzed by studying the cumulative oil production behavior and by linking this behavior with the different variable parameters to add worth statements and discoveries to the previous conclusions, that have been drawn by other researchers, and to help further workers in this field to improve their works and conclusions. Results showed an increase in oil wetness with time. Although no clay minerals were detected in the plugs, the hematite film is responsible for this alteration. Moreover, a small increment of the recovery factor (RF) due to imbibing low salinity water was detected. The main mechanism behind this increment is believed to be the Expansion of the Double Layer (EDL). However other mechanisms are also possible to have contribution in this increment. The capillary diffusion constant (Dc) showed higher values in case of LSW SI than it is in case of high salinity water spontaneous imbibition (HSW SI). This difference hypotheses the higher values of the capillary forces in the second case than in the first case, and hence the higher residual oil saturation (S_or). EDL theory is also in agreement with the increase of the Dc values and reduce the capillary forces, that causes increase of RF. Finally, this works expected to open a space for further and future works in the field of LSWI studies, for example studying LSWI behavior with the of micromodels equipped with synthetic lithology and observing this behavior under microscopy and other imaging methods to provide more reliable conclusions about this problem.

AB - Low salinity water injection (LSWI) became lately one of the most desirable enhanced oil recovery (EOR) and improved oil recovery (IOR) methods since it is considered a low cost, flexible method and environmentally friendly. The increased interest in this method encouraged the researchers to conduct different tests and experiments in different lithologies to explain the mechanism(s) behind it, and then many field pilots to study the compatibility and profitability of LSWI method. Up to now, it is difficult to build a concrete statement about LSWI mechanism and hence in which reservoir it is applicable. The present thesis tries to study the behavior of LSW spontaneous imbibition (LSW SI) in sandstone outcrops plugs, Bentheim sandstone, using Amott test. The work contains plugs preparing, starting from drilling and preserving them until the restoration process starts. The restoration stage aims to establish a favorable reservoir wettability condition, a mixed wet or weak water-wet state. Restoration process contains cleaning process, drying process, saturating the plugs with connate water, with different concentrations and compositions, drain them with crude oil, and aging them at ambient pressure and reservoir temperature. The plugs were divided into four groups; each of them was aged for a certain time. After the end of the preparation period, the test was conducted by placing the plugs in Amott cells and immersing them with imbibed water with different concentrations and compositions. The result was obtained regularly by reading the cumulative oil production. Different scenarios were planned for the test among them using one composition/one concentration during the test or changing the water salinity and/or composition during the test. The results were analyzed by studying the cumulative oil production behavior and by linking this behavior with the different variable parameters to add worth statements and discoveries to the previous conclusions, that have been drawn by other researchers, and to help further workers in this field to improve their works and conclusions. Results showed an increase in oil wetness with time. Although no clay minerals were detected in the plugs, the hematite film is responsible for this alteration. Moreover, a small increment of the recovery factor (RF) due to imbibing low salinity water was detected. The main mechanism behind this increment is believed to be the Expansion of the Double Layer (EDL). However other mechanisms are also possible to have contribution in this increment. The capillary diffusion constant (Dc) showed higher values in case of LSW SI than it is in case of high salinity water spontaneous imbibition (HSW SI). This difference hypotheses the higher values of the capillary forces in the second case than in the first case, and hence the higher residual oil saturation (S_or). EDL theory is also in agreement with the increase of the Dc values and reduce the capillary forces, that causes increase of RF. Finally, this works expected to open a space for further and future works in the field of LSWI studies, for example studying LSWI behavior with the of micromodels equipped with synthetic lithology and observing this behavior under microscopy and other imaging methods to provide more reliable conclusions about this problem.

KW - Wasser mit niedrigem Salzgehalt

KW - spontane Imbibition

KW - Kapillardiffusionskonstante

KW - Wiederherstellungsstufe

KW - Bentheimer Sandstein

KW - Amott Test

KW - Low Salinity Water

KW - Spontaneous Imbibition

KW - Capillary Diffusion Constant

KW - Restoration

KW - Bentheim Sandstone

KW - Amott Test

M3 - Master's Thesis

ER -