Communication Monitoring During Frac Operations – Downhole vs Surface
By Chad Cluver |
Thu, 7 Jun 2012
With the large number of wells being fractured in the tight sand and shale formations, it has become an increasing concern to operators when adjacent producing wells are knocked “offline” by a nearby frac. In these cases, the fracture fluid is intruding on an adjacent well and “waters out” this adjacent producer artificially. An interference test can be used during the fracture job on candidate wells to see if and when each stage of the fracture is in communication with a neighboring producing well. For this interference test, the introduced transient is the pressure resulting from each fracture stage. These studies will allow operators to better understand the well spacing needed for future drills, the impact of interference and develop a pressure versus distance calculation based on the resultant transient. With this data a more efficient fracture schedule can be put in place for the field. Monitoring this data for several wells in real-time via radio communication, which DRC now offers, can also allow for on-the-fly adjustments to current fracturing operations.
We have heard and even read recently that this type of work can only be done when data is captured downhole. This is not accurate. This type of test is easily conducted from the surface and in fact gives the exact same information as downhole gauge data would. We recently had the opportunity to perform this exact type of test for an operator who was fracing two wells that had three producing wells nearby. The operator used SPIDR surface gauges to monitor the three producing wells and also ran a downhole gauge in one of those wells. The monitoring wells were shut-in during fracing operations. The frac job was then carried out on the two new wells over the next several days. The accompanying plots show the surface treating pressure from the frac jobs along with the SPIDR surface data and downhole gauge data. Figure 1 shows the overall plot with all the frac stages for both wells, the SPIDR data from the three monitoring wells (red, blue, and green), and the downhole gauge data from one of the monitoring wells (black). The blue SPIDR data and black downhole gauge data are from the same well. It can be seen that there was communication in two of the monitoring wells (blue and red) but that the green well didn’t seen any communication. The downhole gauge also showed the same communication that was seen in the surface data.
Figure 1: Overall Plot
Figure 2 and 3 are expanded views of the communication events from the first well’s frac operations and then the second well’s frac operations. These views clearly show communication from various frac stages, and that the same response (black and blue curves) was seen both downhole and at the surface.
Figures 2 &3: Expanded Views of Communication from Frac Stages
This test clearly shows that surface data is a perfect alternative to running downhole gauges for frac communication testing, and does so without most of the cost and any of the risk of running wire into the wellbore. DRC now offers a radio communication option that can be used to remotely communicate with several SPIDRs within ~1 mile radius, which allows for real-time monitoring of communication during fracing operations. This is not possible, or would be very cost prohibitive to do, with downhole gauges. DRC always has gauges ready for same day shipment via priority overnight delivery to most places in the United States, or same day via hotshot. We offer free well test planning and consultation, as well as complimentary DFIT analysis when a gauge is rented for the purpose of a DFIT, and are available 24/7 for all your well testing needs.