Some folks here may be unclear about what TNOG does. They spin the fact that TNOG is redrilling/opening up 'old capped' wells as a negative, when in fact TNOG's own business plan is predicated on this activity. Reopening and redrilling wells (using new drilling technology) in places where there was oil is cheaper than wildcatting--where the chance of finding oil is much more risky.
Peter Maupin:
HISTORY: Most of the wells which were drilled along the major fault over which these leases are located were drilled to test the Edwards Lime formation. This was always a prime target as locating the Edwards formation trapped against a fault has resulted in major production from many fields in South Texas. Several wells which were drilled to the Edwards along this fault showed oil in the cores, but also made a high percentage of water on drill stem tests. The initial re-entry well which I recommend to be used to evaluate this project, was originally permitted through the Edwards formation, but was only drilled to the top of that formation – the Edwards was never evaluated. The company seemed to intend to only test the Austin Chalk formation as they perforated that formation between 6127 and 6322 evidently getting no results. They then perforated the formation that produced in the well (5825 – 5860) without apparently setting a bridge plug to isolate the zones – they evidently had a “show” on the mud log in this zone and decided to test it before abandoning the well. This zone “came in” by blowing the perforating gun out of the tubing and beginning to flow immediately. The gas tested sour which leads me to believe that at least some of the gas was produced from the Austin Chalk. They tested the well on 2-25-84 at 123 bopd, 178 mcfpd and 0 bwpd on a 8/64” choke with FTP of 1237 psi. They then shut-in the well in order to permit and to lay a pipeline to sell the gas from the well which took several months. The well was then re-tested on 12-23-84 at 170 bopd, 84 mcfpd, and 15 bwpd on a 10/64” choke with FTP of 800 psi. They produced approx. 3,321 bo and an undetermined amount of gas at which time the well died. They ran a cement bond log on 4-22-85 evidently in preparation for perforating an upper zone. It was plugged on 9-1-85 after sitting dormant for a number of months.
The production zone from 5825 to 5860 shows to probably be tight (low permeability) on the log. This zone is similar to the Taylor Sand which produces a short distance down dip from this well and which will not produce commercially unless it is stimulated by hydraulic fracturing (“frac treatment”). This same company drilled three more wells to this zone along the fault in a northeasterly direction evidently trying to locate a “clean” sand. They set production strings on all of these wells. The first two logs looked similar to the initial well and they were “on strike” (within 2 ft. of subsea el.) , so I presume that the tight sand deterred them from producing from the zone in those wells.
EVALUATION:
Previous operations – Note that the evaluation of operations for the original operator may seem critical at times, but it must be remembered that the price of oil was at approx. $15/bbl (approx. $12/bbl for sour) at the time these operations were conducted. Decisions made would have been based upon the economics for conducting, or not conducting, certain operations and would have been dependant upon the pricing at that time. Many operators did not survive (evidently this one did not) those “hard times”. Therefore this evaluation is not meant to be “critical” of the original operator nor of any personnel.
Initial well - this well was permitted through the Edwards, but the target must have always been the Austin Chalk and Buda formations as the well stopped at the top of the Edwards Lime. They evidently not only had “shows” in the Austin Chalk, but also in a Taylor sand on top of the Pecan Gap showing on the log at 5820 to 5860 ft. They may have also had a “show” in a Taylor sand shown on the log at 4975 to 5000 ft. They set 5 ½” casing to total depth (6577’), but only cemented the bottom with only 165 sks. – they used a multistage tool to cement from 2650 to the surface. The well was initially completed in the Austin Chalk at 6127 to 6322 ft. There is no record of any stimulation, but it is probably safe to say that they would have at least done an acid job “balling out” the perfs in the chalk. There was evidently no commercial production obtained from this formation, so they perforated the zone from 5769 to 5882 which leads me to believe that they had shows through the complete area of perforations and not only in the sand as shown on the log at 5820 to 5860 ft. There is no record that they isolated this zone from the Austin Chalk as no plug back was shown on the RRC form W-2. This zone was perforated through tubing and the pressure “chased” the tool out of the hole. The well was then tested at 123 bo on a 8/64” ck.
They then shut-in the well while they laid a pipeline in order to sell the gas – the gas tested sour which would lead one to believe that at least a portion of it was producing from the Austin Chalk confirming that no bridge plug was set between the zones.
Once the pipeline was finished, the well was retested almost 10 months later at 170 bo on a 10/64” ck. The well then produced approx. 3321 bo and an undetermined amount of gas at which time the well “died”. They did not pump the well or stimulate it.
The primary zone for recompletion in this well is the Taylor Sand on top of the Pecan Gap at 5820 to 5860 ft. It is the author’s belief, in this highly fractured environment so close to a major fault, that hydrocarbons migrated up from the Austin Chalk and probably even as deep as the Edwards Lime into this zone which would “trap” them against the overlying Taylor shales. This would in turn be “trapped” against the major up-to-the-coast fault up-dip from this well causing the reservoir for this field. They tested the Austin Chalk and did not produce it, therefore it is the author’s belief that this zone is not productive in this area as there is no Austin Chalk production along this fault. The Edwards Lime was not evaluated in this well.
Second well – The second well was drilled one month after the initial well was put into production and will be evaluated for re-entry once the first well is fully evaluated.
RECOMMENDATION: This recommendation only covers the primary zone of interest in the initial well
Initial well - Re-enter the well, isolate the zone of primary interest, perforate, swab test, and frac with at least 30,000 lbs. of sand. Evaluate well and complete if warranted.
EXPECTED RESULTS:
Initial well - Author expects initial flow rates in excess of 100 bopd. It also is expected that production from this well would compare with wells in the Serbin (Taylor Sand) Field regarding total production which would equal over 20,000 bsto of production remaining from this zone. At today’s prices, this well would gross over one million dollars if the well actually produced those amounts.
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