Scaling precipitation in the form of calcium or iron sulfate (CaSO4 – FeSO4) appears to be a common problem in most of the wells completed in the Yeso formation in the Permian Basin. Accumulation of these forms of scale in the perforations and the downhole equipment can create severe production losses and therefore they require constant, some times costly, treatments. Additionally, their presence in the wellbore hinders the efficiency of the acidizing procedures, performed by the operators to further increase the productivity of their wells. The objective of this paper is to present an innovative workflow, which significantly reduces the scaling effects and allows the acidizing of these carbonate reservoirs to be more efficient. Results are avialble for more than 20 wells, from Occidental Petroleum’s assets in the North New Mexico region. Details regarding the evolution of the procedure, the types and amounts of the chemicals are extensively discussed in this paper. The procedure starts with the candidate well selection, which preferably are located in the highest OOIP areas to maximize the efficiency. The second step involves the water sampling and analysis to determine the types of scaling and consequently the required chemical treatment. The innovation in this step has to do with the time that converters are left in the wellbore and the extra chemicals that have been added compared to the previous procedures. The last step involves the deployment of the acid downhole, where three different methodologies have been tested and evaluated based on their efficiency and well returns. The proposed approach has been successfully applied to more than 20 wells and the results are encouraging showing an average incremental oil production of ~600% while the execution cost remains very low.

This paper presents a case history where the entire lateral of a producing well was restimulated in a single trip using a novel cost-effective intervention tool designed to provide discrete stage isolation. Lessons learned and job details are discussed and compared with other restimulation methods used in the area. The new method is based on a novel straddle packer system that uses two mechanically-activated sealing elements—as opposed to conventional sealing cups—to overcome wear and bottomhole pressure limitations found in traditional straddle systems. The novel stage isolation system enables higher flow rates and pressure differentials as well as a larger number of stages, therefore reducing the amount of trips in the well required to complete typical refracturing operations. A comparison will be made to conventional refracturing methods based on intervention tools. As a bonus, pressure data gathered during the treatment indicating limited coverage of the primary fracturing job will be discussed. The case study provides the framework to describe how the novel technology enables multiple treatments in a single trip in the horizontal well, therefore reducing the operational time, resources, and cost required to complete a restimulation job. The paper will show how the use of the novel technology reduced operational time by 30% compared to other methods, and enabled the operator to treat a horizontal well with full mechanical isolation in a manner not previously available. In addition, the paper will discuss pressure data gathered during the deployment that suggests limited cluster efficiency on the primary fracturing operation. The results of the paper are relevant because they provide a new cost-effective alternative to conventional restimulation systems that was not available in the past due to inherent technology limitations of existing straddle packer systems. This is important because: (1) the technology described in the paper overcomes these limitations for both vertical and horizontal wells, (2) more refracturing operations are executed by blindly pumping treatments from surface into a full lateral with open perforations without an effective way to mechanically isolate target zones, and (3) the technology may shed additional light on the discussion of cluster efficiency during primary stimulation operations.