Scale removal in sour gas wells has been one of most challenging operations in Saudi Arabia during the last decade. Operators face particularly demanding downhole environments with temperatures above 300 °F, significant concentrations of H2S and CO2, presence of complex mixed-scale deposits with limited dissolution, and risk of H2S release and corrosion with chemical removal methods. These conditions have led to mechanical removal methods using coiled tubing (CT) as the preferred technique for well descaling operations. During the last 5 yr, CT descaling operations have consisted of temporary formation isolation via bullhead using CaCO3 chips as a bridging agent, mechanical scale removal with CT milling and high-pressure rotary jetting tools, and abrasive perforation or matrix stimulation to enhance well productivity. Mechanical alternatives for isolation with bridge plugs are not feasible due to the presence of FeS scale in the wellbore. Wellbore configurations also require pump rates above 2.0 bbl/min to ensure suitable cleanout and transportation of solids to surface. The recent incorporation of CT equipped with a rugged version of fiber optic telemetry and a downhole measurements package into the descaling operations workflow has enabled pumping rates above 2.0 bbl/min. Key bottomhole data has also been obtained, leading to a better understanding of the scale removal progress, optimization of downhole tool operation; reduced well intervention risk, and enhancement of overall job efficiency. During the CT mechanical descaling stage, differential pressure across a high-pressure rotary jetting tool was kept at its optimum range of operation while maintaining slight overbalance conditions to minimize the risk of gas influx and avoid loss of circulation while removing the formation isolation. Throughout the abrasive perforating stage, real-time depth correlation saved one CT run (i.e., ±24 hr), and higher pump rates significantly reduced operation time and maximized shot size and penetration. This paper discusses an enhanced workflow for CT descaling operations where the implementation of the real-time downhole measurements package with an enhanced working envelope resulted in a significant increase in operational efficiency, reduced risk, and optimized job performance.

Drilling technologies are constantly being developed as operators push the envelope limits to maximize reservoir contact and increase hydrocarbon recovery. These advancements in well construction challenge the well intervention community to seek innovative solutions to successfully intervene in these wells. This paper discusses the successful combination of a slim OD measurement-while-drilling (MWD) tool run on coiled tubing (CT) for real-time survey of the open hole lateral wellbore, followed by a stimulation treatment at appropriate depths for all laterals in a single CT run. Saudi Arabia has been in the forefront of maximum reservoir contact well construction with the drilling of multilateral open hole gas wells; thus, the need for CT operations to enhance current offerings and procedures. For this application, several tests were performed to determine the feasibility of the combination of necessary tools to be able to steer, identify, and pump the stimulation treatment in a single run. MWD tools were run on CT in this multilateral gas well, and the stimulation treatment was performed during the same CT run. The common practice in the study area was to run in hole down to total depth (TD) and determine, only by depth difference, in which lateral the CT was located. The uncertainty level increased exponentially when TDs of the laterals were within hundreds of feet because the treatment could potentially be performed in an alternate lateral, rather than the one intended (Ref 1-5). With the use of MWD tools that can relay inclination, azimuth, orientation (steering capacity), pressure and gamma ray, all this uncertainty is eliminated to help ensure a positive lateral identification for proper treatment placement in the well. The MWD tool run on coiled tubing (CT), implemented a procedure explained in this paper to eliminate the uncertainty associated with previous technologies used for in real-time CT positioning inside the wellbore. The CT position is now reliable verified by survey match with real time readings from CT tip, allowing the certification of job placement in the desired wellbore path, to complete the intervention associated to the CT intervention; i.e.,: "a stimulation treatment" to be done specifically and independently for all laterals in a single run on each. This project open the doors for many other MWD-guided CT interventions to be applied in such conditions.

Latest developments in drilling and wellbore completion technologies lead to even more complex intervention conditions. Conventional techniques using slickline or coiled tubing are ill-suited for many of these conditions due to operational complexity, effectiveness, or efficiency. Powered mechanical intervention with e-line alleviates some of these limitations and opens lower risk intervention applications. This paper details two applications: a fishing operation that could not be performed with slickline or coiled tubing and a completion disk rupturing operation where the operator saved 1.5 days. Powered mechanical intervention is a combination of complementary technologies that enable "intelligently controlled intervention operations." Downhole tractors enable access into complex well trajectories. Surface-controlled, powered anchors coupled with a linear actuator can generate very high axial forces with precise and real-time downhole measurements of forces and displacement. Operating parameters can be monitored in real time to prevent damage to damaged completion components. Uncontrolled tool movement due to high differential pressures is prevented. Such precise control of downhole forces and movements enables complex intervention operations previously done with coiled tubing or a full workover. The first application example details a fishing operation. A retrievable plug along with its setting tool was stuck in the production tubing after prematurely setting. Multiple fishing attempts with heavy-duty slickline jars were unsuccessful. Coiled tubing was not deployed as its lack of force precision could have generated excessive downhole force and sheared the fish. An e-line-conveyed linear actuator tool was used to latch onto the fish with the help of an overshot and was released from the retrievable plugs by application of optimal, highly controlled, linear force to minimize damage. The second case involved rupturing a ceramic disk installed in completion. High differential pressure across the disk restricted the use of slickline which could have been damaged due to the high expected differential pressure. The alternative with coiled tubing milling requires a larger personnel and equipment footprint in addition to the associated HSE exposure and lack of efficiency. An innovative technique using the e-line linear actuator and a pointed chisel was devised and deployed. Real-time feedback from the tool sensors gave confirmation of the rupturing of various components of the ceramic disk, and the anchors eliminated any tool movement during pressure equalization. The operation was completed in 12 hours, resulting in time savings of almost 36 hours. An e-line intervention is a low risk, effective, and efficient solution while having an accurate depth and positioning, coupled with controlled downhole operations. With precise control of operating parameters, operations which were previously possible with coiled tubing or workover can be done on e-line more efficiently.

One of the most challenging aspects of producing wells drilled in the northernmost section of the unconsolidated pre-Khuff gas bearing reservoirs in Saudi Arabia is to achieve solids-free production while trying to achieve high gas rate targets. A high degree of success in meeting this challenge has been achieved by implementing a fracturing for sand control strategy, whereby proppant fracturing treatments with a tip screenout design and a combination of other techniques have been successfully placed in a number of producers throughout the gas development program. Subsequently, challenging reservoir conditions, including high temperature and pressure, high stress, heterogeneity, and the absence of stress barriers make placing the fracture treatments very difficult, time consuming and expensive. Therefore, in pursuit of optimum, simple, and cost-effective solutions to the challenge of achieving solids-free gas production, Saudi Aramco successfully set stand-alone screens in wells completed open hole in a sandstone reservoir, and achieved excellent results while significantly reducing costs by eliminating the need for a fracturing treatment and streamlining all other operations. This paper provides details about the geology of the sandstone reservoir, well and screens selection criteria, the screens deployment procedure, post-deployment results, and lessons learned from a two well pilot test. The successful results achieved from the pilot test opened the door for further implementation of the technology and optimization steps.

Gas wells in Field X, south of the giant Ghawar Field, are completed with stand alone screens across a Pre-Khuff sandstone formation as a sand control measure. Although prolific producers, some suffer a severe decline in performance after a period of production, triggering diagnostic work to be performed. Consequently, screen plugging is confirmed and collected samples of present fill are analyzed. Results called for a coil tubing cleanout campaign in order to restore lost productivity. The objective of this paper is to detail the whole operation journey of the fill cleanout jobs that includes fill diagnostic process, assessment of cleanout methods, initial job design, choice of fluids, CT bottomhole assembly tools, execution and field experience, and post-cleanout performance evaluation. A CT wiper trip method has been implemented with either milling or jetting tools. A newly developed rate-activated circulation valve is deployed to aid in lifting solids at high pumping rates as well as jetting acid across the screen interval after fill removal. The fill cleanout campaign has been very successful in restoring well productivity as compared to pre-cleanout and initial post-drilling well performance. A total of 340 MMSCFD of incremental gas rate were restored to-date from 16 cleanout operations. Unprecedentedly, interesting and valuable findings are shared regarding the nature of fill formed inside and/or above the stand alone screens, recommended milling practices to protect CT bottomhole assembly and minimize CT fatigue, the experience of incorporating acid jetting and squeeze in the CT wiper trip method to stimulate damaged formation pack behind the screens, and the preventive measures taken to cope with the fill accumulation issue.