| Popis: |
Distributed temperature sensing (DTS) is used on wells to determine the effectiveness of acid treatments. The technology uses a fiber-optic cable to read temperature in real-time, which allows for validation of fluid placement. In the case studies presented in this paper, effectiveness was determined during the pumping of the job. Using this process, the operator was able to decide if a change to the design needed to be made in real-time during pumping. The effectiveness of the acid job was dictated by how effective the fluid was placed into all zones. Concerns related to the acid treatments included where the acid was placed in the well, if the acid went where it was supposed to, and if the acid went into the first least-resistive zone and subsequent zones went untreated. If the latter took place, then investment capital for gallons of acid was not used wisely. The acid treatments included a wide variation of stimulation methods, such as stimulation of the formation using fracturing or matrix rates, varying the acid percentage, varying the type of acid, using linear, gelled, or crosslinked acid, varying the rate, and using diverters. Historically, on acid jobs, surface readings for pressure and rate were the only indicators to judge the effectiveness of the treatment. As the operator attempted the previously mentioned acid treatments and also monitored the treatment using DTS, it was observed that what is seen at the surface can be misleading. This is because surface pressure can be masked by friction and is therefore not a valid indictor for what occurred down hole, and because diversion can take place without surface indication. DTS allowed for practical adjustment to the diversion strategy for the well that was being treated. Candidate selection is highly recommended when using the DTS-number process. Placement of stimulation fluid was and is critical to well stimulation. DTS allowed real-time analysis to determine in real-time if stimulation was effective during the job. |
