The Khafji and Ahmadi shales in Saudi Arabia are highly dispersive, tectonically stressed formations and tend to result in wellbore instability after prolonged exposure to conventional water-based drilling fluid systems. These time-sensitive formations can cause sloughing shale, packing off, extreme over pull, back reaming, stuck pipe, and in some instances bit and stabilizer accretion, resulting in non-productive time (NPT) to operators. Some off-set wells experienced lost time of up to 30 days, and after failing to continue with conventional water-based drilling fluid, the operator had to plug back and use oil-based drilling fluid to finish the wells. Historically, a standard KCl/polymer/asphalt system was used to drill these shale sections, but due to related NPT and an extensive evaluation program planned for a candidate well, the need for a more robust fluid was identified. Oil- or synthetic-based drilling fluids were not desired due to logistical and environmental concerns. In this challenging well, the operator planned to cut five cores across a series of formations to complete the geological studies previously hindered due to shale-related wellbore problems. These demanding objectives and the notorious history of the field, required a novel solution that could control the formations while maintaining an excellent environmental and logistical footprint. This paper presents details of the successful application of a new high-performance water-based drilling fluid (HPWDF) system using a unique triple inhibition approach to stabilize troublesome zones. In this new system, a proprietary polyamine-based shale hydration suppressant, a unique low-molecular-weight encapsulator, and a co-polymeric nano-sized pore-sealant additive worked in synergy to achieve oil-based fluid performance. In the field application, the system exceeded the operator's expectations, with no fluid-related downtime and successful execution of five coring runs. After coring and logging, casing was run and cemented smoothly, even after 42 days of wellbore exposure. With similar formations drilled across the Middle East, this solution has the potential to be used as an environmentally-friendly alternative to oil-based fluids in the Middle East.

Drilling unconventional horizontal extended reach wells has always been challenging; coupled with geological and drilling challenges of an exploratory field, they present the perfect combination for non-productive time (NPT). To maximize production, it is paramount to reach the whole reservoir and extract hydrocarbon resources efficiently. Moreover, to increase profits, the well should be drilled in minimal operating time, which in turn reduces operating expenses. This paper presents a detailed study and outline of neoteric practices used to drill four such wells in an unconventional field that resulted in the elimination of NPT and reduced drilling and completion time to less than one-third. Thirteen wells have been drilled under an unconventional gas exploration project since 2007 with a historical average drilling and completion time of 95 days (and best record of 60 days). Numerous challenges associated with the field (i.e., loss of circulation, hole instability, stuck pipe, bit balling, casing held up) led to an average NPT of 40 days. To eliminate NPT and improve operational efficiency, a detailed study of the offset wells' drilling and mud programs was conducted with the operator. After an in-depth review and analysis, a revised mud program was adopted containing a holistic approach to encounter the challenges faced in offset wells, as they were all interconnected. The use of a novel rate of penetration (ROP) enhancer and proprietary software for precise hydraulics management resulted in improved ROP, elimination of bit balling, and excellent hole cleaning. A modified bridging strategy, using software simulations validated by lab testing and changes in sweeping procedures to avoid wash out and removal of filter cake, cured losses successfully and improved overall hole condition. A totally new composition for mud mixed on location in the event of total losses and use of innovative polyamine inhibitor for reactive formations eliminated hole instability and stuck-pipe incidents. Implementing these customized solutions, combined with precise operating strategy, led to zero NPT and a reduction of average drilling and completion time to 29 days; this saved a total 245 days and an overwhelming cost savings in drilling fluid services cost for the four wells drilled to date. This paper discusses the outstanding performance achieved while using the existing setup by modifications in operational procedures and inventive techniques. It also describes cost effectiveness, overall performance-based results, and challenges while implementing the strategies. A detailed comparison of all the challenges that occurred while drilling and the proper troubleshooting steps are also discussed. Finally, the paper compares the existing results with previous drilling techniques, which may help operators with the future development of their respective fields.

Lost circulation is a prominent problem in almost all fields of Saudi Arabia. Losses can vary from partial to total and sometimes also initiate other drilling related issues, such as stuck pipe, kick, and wellbore instability. These complexities make it paramount to cure losses as fast as possible to minimize non-productive time. Conventionally, discrete pills formulated using a material blend with broad particle size distribution (PSD) are employed first as one of the more popular approaches for curing severe lost circulation. The lost circulation material concentration and PSD are increased in the pills based on loss rates, thus under severe and total loss conditions the pills require use of specialized pumping equipment, by-pass tools, and even the removal of the BHA. Unfortunately, dealing with severe losses in the Kingdom, success rates with these pills are very low. A solution for severe to total losses pumpable through a BHA was the operator's wish. In this paper, successful field applications proving the advantages of a new high-fluid-loss, high-strength (HFHS) lost circulation solution in different fields, formations, and sections will be covered in detail. The paper will also include operational best practices for mixing, pumping, spotting, and squeezing HFHS pills, lesson learnt, and recommendations for future applications.

Historically, stuck pipe has been one of the biggest causes of non-productive time (NPT) in Saudi Arabia, resulting in loss of tools, reduced hole footage, and potentially endangering well objectives. Stuck pipe still tops the list of costly non-productive time events worldwide, ahead of items such as well control incidents, waiting on weather, lost circulation, equipment failures, and rig associated problems (Hunter et al., 2014). In Saudi Arabia, stuck pipe incidents occur in all drilling sections. While drilling top hole sections, they are generally coupled with partial to total losses; in deeper sections, they are induced due to high overbalance. Stuck pipe in top hole sections requires a solution that is environmental friendly, as many aquifers used by local communities are also present in these sections. Since the presence of aquifers limits the use of conventional hydrocarbon-based solutions, a novel non-hydrocarbon-based pipe freeing agent was developed. This new technology eliminates the need to isolate the stuck pipe pills at surface after circulating them out; they can be incorporated into the circulating system because of their excellent environmental footprint. When added in the drilling fluid, these pills improve system lubricity. This paper presents an overview of successful applications of this novel chemistry in both the top-hole section with total losses and in the production section with overbalances up to 4,400 psi. Performance-based results and advantages of using this solution to improve overall drilling performance will also be discussed in detail. Best practices and lesson learnt for mixing, pumping, displacement, and soaking will also be covered in detail to provide a guideline for operators in similar conditions across the Middle East.

From a drilling operation's prospective, wells drilled in the direction of maximum horizontal stress are ideal as they have less risk of wellbore instability. Unfortunately, when these wells are hydraulically fractured, the fracture grows along the wellbore in the direction of well azimuth. To avoid overlapping of two adjacent induced fractures and thereby communication between stages, only two to three multistage fracture treatments can be performed. To increase production and enhance recovery, operators now drill horizontal wells along the minimum horizontal stress direction to generate multiple transverse fractures during the stimulation stage. However, drilling along the minimum horizontal stress direction requires higher mud weights to minimize formation breakout due to prevailing in-situ stress conditions. This increased mud weight leads to higher differential pressures across the depleted reservoir layers, which when coupled with formation instability, creates greater challenges like stuck pipe, breakouts, and breakdowns. During the completion phase, the stiff multistage fracturing string containing multiple packers makes it more difficult to run through a slim hole, resulting in multiple failures, stuck incidents, and non-productive time. While drilling high angle wells in Saudi Arabia's onshore gas fields, production holes are drilled through many reservoir layers. A few are highly depleted and the rest are highly pressurized. A high degree of skill is required to manage drilling fluids and drilling practices so that the depleted layers seal efficiently, thus preventing development of a thick filter cake and differential sticking incidents. This paper outlines a successful neoteric methodology adopted in these challenging wells after a detailed analysis of offset data and failure incidents. The outstanding performance achieved by adaptation in operational procedures while using the existing setup in both drilling and completion phases, challenges while implementing the strategies, and comparison of results with previous drilling techniques will also be covered in detail to help operators drilling in similar conditions.