ABSTRACT

The area discussed in this paper extends from southwestern La Salle county through north central McMullen County, Texas.

Several drilling procedures are used, but one suggested here is: drill to the top of the Edwards and core at least thirty five feet of porosity, then open hole drillstem test and if test is successful, drill at least two hundred feet, set pipe and do any further testing through production string.

Costs range from $100,000 to $130,000 for a dry hole and from $180,00 to $230,000 for a completed well. Both power and steam rigs have been used for drilling with approximately the same price.

Surface casing requirements are from 1000 to 5000 feet surface, protection string only around salt domes, N-80 17 lb. 5 1/2 casing on bottom 4000 feet, and plastic coated tubing.

Electrical logs suggested are: the Neutron or 37 1/2 inch Limestone Lateral for porosity. Induction log for resistivity and SP Curve. Microlog or contact log to indicate wall cake thickness and hole size.

Mud program suggested is diesel emulsion at the top of Midway shale. Mud weights of 11.1 to 11.5 to be used when topping Edwards. A new surfactant type mud is being used to cut mud solidification. Mud solidification is due to high bottom hole temperatures. Lime base mud can be used in the Tilden area when no Kiamichi is expected.

High bottom hole temperatures may be causing completion equipment failure.

Acid program recommended is 10,000 gals. of regular limestone acid with 500 to 1000 gals. mud acid followed by some surface tension reducing agent. Edwards will take acid at 4200 pounds pressure.

Reservoir conditions are 10% porosity, recovery 700 to 900 MCF per acre foot, plus 10 to 15 barrels condensate per MMCF. Well head pressure is approximately 5300 pounds. All gas here has hydrogen sulfide.

Production tests indicate that any water produced initially will disappear after testing. Tests and sale of gas for drilling indicate that wells clean very slowly and pressures are higher after some production.

Gas is being contracted for 14 cents per thousand with considerable interest from transmission companies. Production procedures and drilling techniques are in the experimental stage.