Tales from the Oil Field of Bygone Days: part 4 - E-Log Adventures

Tales from the Oil Field of Bygone Days – Part 4 – E-Log Adventures

I got to see my first E-log, casing run, and cement job on an early well we mud logged. It was in Erie County, Pennsylvania. The boss drove us up there in his truck. I was the new guy and had to sit in the middle on a six hour trip. We unloaded the trailer and the boss left. We worked logging a fast Devonian well on air. It was a small rig with a three-man crew. The rig shut down for the night and the rig crew left. We had no electric, no vehicle, and it was dark. The well was spewing gas – something that would not be allowed these days for good reason. We made a little camp fire, ate some food, and crashed out. The other mud logger, one of my mentors on the job, would eventually die in a car accident on the way back home from a well. The boss was late getting back so the next night after we finished we had to wait for the cementers to finish because their trucks had us blocked in. I got to see how the e-log looked which was cool at the time. In the succeeding years I would attend several hundred e-logging jobs, make decisions on running casing, and pick casing setting depths and where to set bridge plugs to isolate frac stages and DV tools to manage cement placement.

One time we were supposedly logging up through the Clinton section in northeastern Ohio near 3500 ft in depth except the log curves looked really weird as I glanced at them. We were quickly logging the shallow section with Gamma Ray and Neutron before logging the deep section with more logs. We were skipping section and logging the Clinton (supposedly). This so-called “skip logging” was common in those days to save time and money. The logging engineer said there’s the Packer Shell – a hard zone of fossiliferous limestone above the Clinton but it did not look at all like the Packer Shell. I said I think something is wrong as the rock continued to look different. I had not seen too many shallow log sections in this area but we were supposed to be close to 2000 ft when the logging tools started out of the hole logging about 2ft per second – that gave us about 15 seconds to stop the tools from hitting the crown which the engineer was able to do. Apparently they made a serious depth error and the Packer Shell was actually the Berea Sandstone.

One time on a Clinton well near the southern tip of Ohio I went down for the logging job. The well hit saltwater in the Newburgh, or Lockport Dolomite. When I got there it shot up nearly 30 feet straight up the derrick as they were tripping out. Then about 30 minutes later it did it again – making a bit of a mess on the rig floor. They were now rigging up to log and we wondered if it would surge again. Sure enough about 30 minutes later it did again. Now it seemed quite predictable – like a geyser. Sure enough “old faithful” did it a few more times on that 30 minute interval. That must have been the time it took to pressure back up so it could flow.

One time on a well in Southern West Virginia we couldn’t get the logging tool down the hole to see the zone we wanted to see. It was a thin oolitic zone in the Greenbrier Big Lime that was a potential gas reservoir. The logging tool got caught about 60 ft above the zone. One of the logging engineers had an idea. Since they had new slim hole tools they could bring them out and run drill pipe back down through the stuck zone yet still above the zone of interest and run the slim hole tools through the drill pipe and see the zone. It worked and we were able to run pipe and produce the zone after some reaming through the tight section.

One time in Southern Ohio the logging tool got stuck in surface casing. We suspected a mud ring where mud from below got stuck around the inner part of the casing. We were talking about running something in to clean out the casing when one of the rig crew had an idea – he took a hose and started filling the hole with water. The water was coming up and out near the top and we were about to give up on the idea when all of sudden the water column dropped down the hole. The fluid level was a little higher than usual on the log but the idea worked.

One time we bought a well in Southern West Virginia that had a casing leak. The well still had production potential but was required by the state to be plugged so we plugged it. We decided to offset the well about 40 feet away. We wanted to test a prospective sand that was not tested in the other well although it produced from a couple other zones. The sand was about 30 ft thick. It was not a real mappable sand and we had not correlated a sand in that section but there were some “stray” channel fills in this area that we knew were thin. Some of those channel fills could produce significant amounts of gas but some had high water cuts so they were basically bonus reservoirs that we produced if their water saturations were reasonable and they had temperature log kicks. Well we drilled the well and had the other zones but the 30 ft sand – it was gone. There was no sand there at all and we were just 40 feet away. Aw crap. While channel chasing could be fun, it was not that day.

In the Oriskany fields of Pennsylvania I got to see repeat sections where reverse faults and thrust faults caused zones to be repeated on the logs. We first picked out the repeated sections on our ROP logs (rate of penetration). One well hit the top of the Onondaga Limestone three times. The usual procedure was to drill down to the Onondaga then trip out for a new bit and make up the long flow line to a lower pit as the well would be flared while drilling in on air. These were big wells with big flares. We usually got about 18 hours off during the trip which was nice. If the well was big they would kill the flare and continue the well through the required “rat hole” on drilling mud. A similar procedure was used to drill Knox Unconformity (Beekmantown, Rose Run, and Trempeleau) wells in Ohio.