Gravel Packing Controls Unconsolidated Sand in Venezuela Field

Abstract

Abstract Sand control has been the major problem encountered in producing oil from the unconsolidated Miocene sands in the Lagunillas area of Venezuela. One of the first completions developed to prevent excessive sand production was the combination oil string in which pre-perforated casing was employed. In most cases this method was unsuccessful in controlling sand and was replaced in 1951 by a special slotted liner completion. The slotted liner technique has been effective in controlling sand and in obtaining high volume producers in the Bachaquero sand member. However, as a satisfactory completion depends upon the ability to wash the well into production outside the liner, this technique will soon become obsolete because of the declining reservoir pressure in the Bachaquero field. A program to evaluate gravel packing as a replacement for the slotted liner technique (see Fig. 1) and to provide a sand control method for use inside existing pre-perforated completions was initiated in April, 1956. Forty-three wells have been gravel packed in the Lagunillas Dist. through Sept. 25, 1957, with two jobs considered as failures. Thirty of these wells are producing at an average rate of 520 B/D of 12 to 180 API gravity crude as compared to 268 BOPD for the average offset well. Eight wells are awaiting installation of production equipment and are expected to be satisfactory producers when opened to production. Various problems concerning fluids, liner slot sizes and loss of gravel to the formation have been encountered. Solutions to these problems have been found and procedures for both open-hole and inside gravel packs have been developed that can be applied with confidence to the sand control problems that exist in the Bolivar coastal fields. Introduction A program to evaluate the applicability of gravel packing as a sand control method to wells in the Lagunillas Dist. was initiated in April, 1956.