In Saudi Arabia, conventional oil reservoirs have been treated using conventional stimulation methods. The challenge is that many of the formations now are tighter and require improved stimulation methods. Fracturing is a major topic discussed in the industry as of late and as such, using it in this formation will serve as a trial to shift from conventional stimulation methods to fracturing when facing tighter formations.This particular acid frac was performed in a tight carbonate formation. The chosen well is a newly drilled trilateral producer completed with a multistage frac completion in the motherbore and will serve as a pilot well for this reservoir in the area. The acid frac was a seven stage completion utilizing hydraulic fracturing. Several methods using pressure and injection were used to determine reservoir fracturing response and petrophysical properties. This paper will discuss the first multistage acid frac performed in an oil producer in Saudi Arabia. It will examine the entire process of candidate assessment, job preparation, and execution. In addition, the paper will discuss challenges faced, solutions taken, and the post-decision results. The paper will show how an injectivity test performed pre-and post-frac was used as a benchmarking tool to analyze the effectiveness of the frac. Finally, we will discuss the flow back of the well, initial results, lessons learned, and optimization of future jobs.
Over the last 10 years, matrix stimulation of multilateral wells has been one of the most fascinating and technology-driven interventions in the oil and gas industry due to the several challenges involved in this kind of operation. Overcoming these challenges, which include lateral identification and accessibility, reservoir assessment, and accurate placement of stimulation fluids, has encouraged operators and manufacturing and service companies to develop innovative techniques and novel technologies. In Saudi Arabia, coiled tubing (CT) equipped with real-time downhole measurements and a multilateral identification tool (LIT) has been one of the most valuable technologies to enhance the interventions in multilateral wells. Initially, the ability to monitor real-time data enabled a more efficient operation of the LIT, as well as optimizing and properly placing the stimulation treatment fluids by avoiding the identified high-intake zones across each lateral. Most recently, the incorporation of gamma ray tool into the real-time downhole measurements package allowed a faster identification of each lateral and accurate depth correlation for pinpoint acid stimulation; nevertheless, when this technology was deployed, pumping rates were significantly limited to a maximum of 2.0 bbl/min due to limitations on downhole tools and optical fiber installed inside the 2 3/8-in. CT. In some cases, this barrier also represented a drawback for optimum fluid penetration and efficient diversion across the zone of interest during the stimulation treatment. This paper documents the first worldwide applications of the enhanced version of a real-time downhole measurements package deployed on 2 3/8-in. CT for the successful matrix stimulation of a multilateral power injector well in Saudi Arabia, where the barrier of 2.0 bbl/min was far exceeded while maintaining intact all downhole readings. The operation represented a significant increase in operational efficiency and set a new record for this technology. A total of 4,585 bbl of stimulation fluids were injected across the open hole laterals (7,685-ft combined on both wells) at maximum rate achieved of 4.6 bbl/min, which were successfully accessed with the use of the LIT in a single run without the need to pull out the CT to surface. The use of enhanced the real-time downhole measurements package reduced the operational time by almost 50%, enabled more effective formation damage removal by injecting stimulation fluids at a higher rate, provided real-time depth correlation, verified access via gamma ray to each lateral without the need to tag total depth, and resulted in a tangible cost reduction.
Throughout the history of the oil and gas industry, numerous developments have been made, especially in the drilling sector. In Saudi Arabia, wells that historically have been drilled and completed vertically and deviated have been completely shifted to horizontal and even past that to extended reach and multilateral wells. Horizontal wells have enhanced the possibility of draining relatively thin formation layers, maximizing reservoir contact, decreased water and gas coning, increased exposure to natural fracture systems in the formation and better sweep efficiencies. On other side, drilling a horizontal well and further drilling a lateral adds the complexity with respect to lateral accessibility, especially during the workover and well intervention services. Considering the challenges associated with drilling multilateral wells, completion and well intervention, an innovative completion was installed for the first time ever in an oil well in Saudi Arabia. The innovative completion technique introduced the idea of a pseudo-multilateral where the other laterals are not actually drilled but the completion consists of needles that extend into the formation enabling the well to have more reservoir contact. The innovative pseudo-lateral completion was installed during a workover operation in an oil well in Saudi Arabia for the first time, whereas, the well was completed as an open hole in a tight formation with an electrical submersible pump (ESP) initially. Prior to installation of the innovative pseudo-multilateral completion, the well was facing issues to sustain production and though the well was stimulated using coiled tubing (CT), the intervention did not meet the objectives. Therefore, after the installation of an innovative pseudo-multilateral completion, followed by a stimulation intervention, the well was able to produce at a stabilized production rate. To evaluate completion effectiveness of this pseudo-multilateral technology, the multispinner production logging via CT was conducted to determine which pseudo-laterals were contributing to the inflow. Since this is the first production log in this type of completion, the logging bottom-hole assembly and procedures were modified to overcome the challenges, such as completion internal geometry and profile. The production logging was executed successfully and the multispinner production logging analysis shows a homogenous production profile. The logging result provided the input in optimizing the pseudo-multilateral completion and increasing the confidence to pursue this technology in other applications. This paper will present the process in designing, executing and evaluating the first production logging in the pseudo-multilateral completion. It will examine benefits and challenges of running production logging in such a completion. In addition, it will display advantages and disadvantages of installing a pseudo-multilateral completion as evident from well testing through the production logging.
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