An Automatic Device for Packing Particulate-Matter Columns Reproducibly

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Abstract
Introduction Much research aimed at developing clay stabilization chemicals, plugging and diverting agents, grouting processes, enhanced oil-recovery treatments, and processes, enhanced oil-recovery treatments, and sand consolidation methods requires flow studies using unconsolidated formation sands or synthetic sandpacks. They may contain calcareous materials and clays in addition to sand. Generally, Hassler sleeves and Teflon-sleeved chambers have been used to contain the sands. The reproducibility of the permeability and, thus, the flow rate of columns permeability and, thus, the flow rate of columns prepared using manual packing techniques has been prepared using manual packing techniques has been poor, particularly when the columns were packed by poor, particularly when the columns were packed by different workers. Clay-bearing sands have been especially difficult to pack uniformly due to segregation of the differently sized particles. Reproducibility of the initial brine permeability was obtained by discarding 15 to 20% of the columns that had a permeability outside a defined range of values.Improved mixing techniques were used to prepare the particulate matter compositions, but these did not produce a dramatic improvement in experimental reproducibility. Study of the manual packing technique indicated that the variables probably responsible for poor reproducibility were (1) the rate at which the particulate material was introduced into the column, (2) the pressure at which the material was forced into the column, and (3) the duration of the entire process. The procedure of introducing the particulate material into the column through a tube particulate material into the column through a tube that simultaneously packs down the particulate material already present in the column was thought to produce a packed column having a lower permeability at the bottom than at the top of the packed material. Some segregation of differently sized particles probably was occurring. particles probably was occurring. The automatic packing device described here controls each of these variables and has been used routinely to pack columns having a range of permeability from less than 50 md to greater than 400 md. The salient features of the apparatus are depicted in Fig. 1.1. A regulator (a) controls the force with which a vertical tube (b) containing the particulate matter strikes the bottom of the column (c) or the top of the previously packed material. The particulate matter previously packed material. The particulate matter flows into-the column from holes drilled radially in the vertical tube. A side arm (d) is used to place the particulate matter into a reservoir above the tube. A particulate matter into a reservoir above the tube. A compressed air line (e) supplies the required pressure.2. One timing device (f) controls the rate at which the tube undergoes vertical upstrokes and downstrokes. A second timer (g) controls the time interval between strokes.3. A hydraulic fluid reservoir (h), piston (i), and a regulator (j) control the rate at which the chamber (k) holding the column drops, allowing the particulate matter to fill the column gradually. The pressure required to move the chamber down can be adjusted using the regulator (j). A slight downward movement of the chamber diminishes the applied pressure from the downstroke of the packing so that it is below the threshold level required to move the chamber. Thus, the chamber is lowered slightly at each downstroke. This provides a column in which permeability does not vary greatly with column height.The permeability of the packed column is controlled by: the composition of the particulate matter; the number, size, and location of the hollow passages in the vertical tube through which particulate material is introduced into the column; the pressure driving the tube in its motion; the time duration of the downstroke and upstroke; the time interval between strokes; and the critical pressure required to move the chamber downward. The most important of these have been the pressure driving the vertical tube and the critical pressure needed to force the chamber to drop slightly. JPT P. 733

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