As operators are drilling more and more complex wells in technically demanding basins; they are also looking to be cost effective and to minimize impact on the environment. This has driven the industry in recent past to develop and use high-performance water-based drilling fluids (HPWBDF). A drilling fluid that has performance like oil-based drilling fluids and environmental acceptance of water-based drilling fluids is the need of the times. In the whole Gulf region, wellbore instability is a major cause of nonproductive time. Drilling time-dependent shale formations have always been challenging; hole instability, tight hole, back reaming, and well packoff have been experienced in both vertical and highly deviated wells. These formations have a combination of reactive and dispersive clays in the shale formation, interbedded formation sequences, microfractures, and sometimes they can be tectonically stressed and overpressured with high-stress anisotropy. Such features make these formations time sensitive and highly unstable, thus they need multiple levels of inhibition. For this reason, oil-based drilling fluids are fluids of choice for many operators. In current times, the exceptional drillability of nonaqueous drilling fluids in high-angle, long-reach horizontal wells is offset by tremendously high logistical and waste-management costs that can account for half of the total drilling fluids cost. Recognizing these challenges, a novel HPWBDF was developed that could provide high level of inhibition and an excellent environmental and logistical footprint. This paper presents a successful application of a new HPWBDF using a unique triple inhibition approach. The system exceeded customer's requirements by successful execution of all well objectives. The client used this system in three consecutive sections instead of the single planned section. This solution has the potential to be used as an alternative to oil-based fluids in all similar formations drilled across the Middle East.

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.

From a drilling operation's perspective, the wells drilled in the direction of maximum horizontal stress are ideal as they have less risk of wellbore instability. However, 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 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 and advanced geomechanics studies to minimize wellbore instability 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 such as stuck pipe and formation 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 pipe events, and nonproductive time. While drilling horizontal and high-angle wells in a giant onshore gas field, 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 design and manage drilling fluids and drilling practices so that the depleted layers seal efficiently, thus preventing the development of a thick filtercake and differential sticking incidents. This paper outlines a successful neoteric methodology adopted in these challenging wells in a deep gas drilling lump-sum turnkey project in the Middle East 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 to help operators drill successfully in similar conditions.