Review of Cycling Operations in the La Gloria Field

Purpose

Cycling operations have been successfully conducted in the La Gloria Zone foreight years. The cycling of this zone is now virtually completed. It isproposed that this report shall review the cycling operations of this reservoirso that the industry can more accurately evaluate the cycling process as aproduction method.

Introduction

The La Gloria project is one of the largest cycling operations in the Stateof Texas. The gas rights in the field are unitized in three operating units. Bymutual agreement Magnolia Petroleum is the designated operator of the projectfor the 12 operators owning the gas rights. The La Gloria Corp. is the ownerand operator of the cycling plant. The development and operation of the fieldare under the direction of an Operators Committee comprised of a representativeof each operator. The Operators Committee is assisted by an Engineering andGeological Sub-Committee.

The La Gloria gas field is situated approximately three miles north ofFalfurrias, Tex., and lies principally in the extreme south end of Jim WellsCounty, with its outer limits extending into the north end of Brookes County,Tex. It is a simple elliptically-shaped dome which has a closure of 350 ft. Thefield encompasses a surface area of 5,500 acres. The gas reserves are found in20 major sand zones lying in the lower Frio formation and Transition Zone ofthe Upper Vicksburg formation. Approximately 40 gas wells have been drilled inexploring and developing the gas reserves of the field.

Discussion

The La Gloria sand occurs in the lower Frio formation at a depth of 6,515 ft atthe crest of the structure. The average sand thickness for this zone is 32 ft.The reservoir initially had a gas column of 125 ft and did not have an oilcolumn. The sand has an average porosity of 22.2 per cent and an averagepermeability of 521 MD. The productive area of this zone is 2,680 acres. Theoriginal bottom hole pressure was 3,470 psia and the formation temperature is203?F. The average percentage connate water in the reservoir space has beenestimated at 20 per cent.

T.P. 2952