Reaching bottom with logging tools is difficult when the well is highly deviated and has significant pressure overbalance. This often leads to mechanical and differential sticking risk on cable operations and the desired depth not being reached. The normal practice is to deploy formation testers on drill pipe (pipe conveyed logging – PCL). This paper aims to provide guidance to operators for performing safe and efficient wireline formation pressure testing jobs in challenging conditions, saving considerable rig time. It is critical to understand the factors which cause tool obstruction and cable sticking. This helps to optimize the conditions needed for successful wireline operations and prevents high-impact events, such as tools getting stuck, fishing operations, wiper trips, cancelled logging and PCL jobs. The main contributing factors were analyzed and divided into different categories: well design and trajectory, borehole conditions and geomechanics considerations, drilling fluid properties and wireline equipment selection. A tailored operational workflow with detailed risk assessment with prevention and mitigation measures were combined into a practical guide and then it was implemented to perform a series of jobs. Following the new systematic approach, wireline logging jobs could be safely conducted in several wells across 8-3/8" and 5-7/8" sections in a challenging drilling environment. The maximum inclination was 60° and maximum overbalance of 3,920 psi. The vast majority of planned pressure points were collected and there weren't held ups or overpulls observed during the operations. For the tester tool to reach the bottom, it was essential to have a proper well design and trajectory construction, good borehole quality with minimum disturbance and exposure, right mud weight selection together with fit-for-purpose drilling fluid and bridging plan. All best practices and lessons learnt, were put together to a guide and made available to the project team for future operations. This technique was adopted as the new standard for logging through carbonates formations in deviated sections in the field, with high depletion. As operational costs are a concern in long deviated logging, optimization done using alternative methods offer benefits in terms of rig time and efficiency. If the main risks aren't assessed properly, then it incurs significant costs and inefficiencies. This innovative multidisciplinary approach integrates different domains to perform wireline formation testing operations in a cost effective and time efficient manner when compared to running logs on drill pipe. This method will serve as a reference for operators and service providers to achieve step changes in similar operations. The key elements of this initiative will be described in detail in the paper.

The low success rate of curing complete loss of circulation across fractured carbonates in the field, where all kind of loss circulation material and unconventional plugs were tried without success, required better understating of the fractures and changes to the well design and drilling practices to ensure proper zonal isolation and well integrity. This paper describes the successful planning and implementation of these changes and how they improved overall well construction performance. As most of the total losses occurred in the intermediate section, which combines pressurized water injection formation with depleted oil-bearing reservoir, curing process was very often never achieved. Understanding that some areas of the field are naturally highly fractured, but specially characterized by carbonate karst, dissolution, and mega fractures, was critical to map the high-risk area and modify the well design and practices. The innovative risk-based well design was deployed to a series of wells across the field. The isolation between low- and high-pressured layers to prevent casing-to-casing annulus (CCA) sustained pressure[NMF1] throughout well life and, possibility of drilling ahead with no returns with one of layers already secured by previous casing were implemented. Suitable casing seat was selected in such way that critical high pressure and depleted zones were identified and isolated. Water-bearing layers in the upper section was efficiently balanced with enough mud weight and casing point set above risky zone with addition of double mechanical barrier with gas tight feature. Highly fractures formations in the lower section were drilled with significant lower mud weight at minimum overbalance, surge stresses and best possible fluid rheology. Casing running practices were adjusted to avoid inducing losses, cement slurries redesigned for optimum properties at minimum equivalent circulating density (ECD) and cementing jobs were conducted with full returns. The total loss events were significantly mitigated in the campaign, with overall 15% well performance improvement, ensuring zonal isolation, and reduction of future CCA occurrence, which can compromise the production casing integrity after fracking job, involves high remedial work costs, longer shutdown phase and possible production loss. This solution balances performance and costs can serve a technical reference for future application in the basin or other regions with loss-prone environment across large and fractured formations, and well integrity is a concern for operators and service companies.

In the Oil and Gas industry, there is a constant look for time and cost savings through performance enhancement and risk reduction. Not less important, wellbore quality becomes a crucial factor across target production intervals which enable safe and optimum completion operations in the well. While the techniques to drill wells constantly evolve, technology is advancing at faster pace every year. The application of new tools and digital technologies is the step change from progessive growth to exponential increase in performance. This paper contains a detailed description of a successful implementation of a combined integrated strategy, including the procedures established to maximize both; performance and wellbore quality in highly deviated and lateral horizontal sections in deep gas wells in a giant gas field in the Middle East. It describes the application of specific technologies that helped to improve wellbore quality and allowed corrections in Real Time.

The evaluation of horizontal gas wells using routine logging tools is more challenging, when compared to vertical holes. The standard practice is to deploy logging tools on a drill pipe, typically known as Pipe Conveyed Logging (PCL), however, this standard conveyance method is risky and time-consuming. Therefore, this paper focuses on the optimization project to convert all PCL runs, including formation testing, into time-efficient operations by using groundbreaking wireline conveyance techniques. Assessing fit-for-purpose alternative options is necessary to de-risk open hole logging operations. Firstly, a thorough review of the logging requirements was performed for reservoir section in each hole size, namely 8-3/8″ and 5-7/8″. Concurrently, the wireline conveyance techniques present within the services provider's portfolio, were evaluated against the normal borehole conditions, open-hole risk profile and potential saving opportunities. Thus, the tailored risk-based workflow created suitable conveyance methods for each application. It ensured that the newly initiated solutions matched with operational needs. Considerations were also made to upgrade the existing technologies to meet the logging objectives. An extended-reach wireline deployed tractor system was implemented to pull the tools for over 2,800 ft of open hole of up to 87 degrees inclination, across highly depleted carbonates in the 8-3/8″ deviated section. This technology combines the use of an electric-driven tractor with low-friction taxi wheels. It provides better data quality due to enhanced tool stand-off and saves more than a day of rig time compared to a conventional PCL run. In addition, in the 8-3/8″ section, formation testing runs were conducted using high-tension cables with up to 60 dg inclination, and maximum overbalance of 3,920 psi. Up to 14 pressure points per run were taken down to 13,700 ft without deploring any differential sticking incidents or tool obstructions. PCL runs were replaced with through-the-bit logging services across the 5-7/8″ horizontal reservoir, typically stretching across 5,000 ft. This unique conveyance platform is designed for long laterals, and it consists of a suite of logging tools which is integrated to the drill string, allowing the combining of logging operations and reaming trips. Prior to running the stage-frac lower completion, the reservoir was successfully logged. This innovative engineered approach was implemented across large scale, multiple rigs, in one of the most prolific gas fields, accelerating the learning curve of logging operations optimizations. It has helped to decrease risk and lower well construction costs, by saving more than one day of rig operation time. Thus, alternative conveyance methods will enable operators and service companies to work tightly together, driving logging efficiency in the Middle East and other basins.

Lost circulation is one of the major challenges while drilling oil and gas wells across the world. It not only results in nonproductive time and additional costs, but also poses well control risk while drilling and can be detrimental to zonal isolation after the cementing operation. In Ghawar Gas field of Saudi Arabia, lost circulation across some naturally fractured formations is a key risk as it results in immediate drilling problems such as well control, formation pack-off and stuck pipe. In addition, it can lead to poor isolation of hydrocarbon-bearing zones that can result in sustained casing pressure over the life cycle of the well. A decision flowchart has been developed to combat losses across these natural fractures while drilling, but there is no single solution that has a high success rate in curing the losses and regaining returns. Multiple conventional lost circulation material pills, conventional cement plugs, diesel-oil-bentonite-cement slurries, gravel packs, and reactive pills have been tried on different wells, but the probability of curing the losses is quite low. The success with these methods has been sporadic and shown poor repeatability, so the need of an engineered approach to mitigate losses is imperative. An engineered composite lost-circulation solution was designed and pumped to regain the returns successfully after total losses across two different formations on a gas well in Ghawar field. Multiple types of lost-circulation material were tried on this well; however, all was lost to the naturally fractured carbonate formation. Therefore, a lost-circulation solution was proposed that included a fiber-based lost-circulation control (FBLC) pill, composed of a viscosifier, optimized solid package and engineered fiber system, followed by a thixotropic cement slurry. The approach was to pump these fluids in a fluid train so the FBLC pill formed a barrier at the face of the formation while the thixotropic cement slurry formed a rapid gel and quickly set after the placement to minimize the risk of losing all the fluids to the formation. Once this solution was executed, it helped to regain fluid returns successfully across one of the naturally fractured zones. Later, total losses were encountered again across a deeper loss zone that were also cured using this novel approach. The implementation of this lost-circulation system on two occasions in different formations has proven its applicability in different conditions and can be developed into a standard engineered approach for curing losses. It has greatly helped to build confidence with the client, as it contributed towards minimizing non-productive time, mitigated the risk of well control, and assisted in avoiding any remedial cementing operations that may have developed due to poor zonal isolation across certain critical flow zones.