The operational drilling history in a particularly challenging shale consistently shows that once the formation's shale reacts, and starts to disperse, in the face of a typical water base mud application, a variety of hole problems are experienced by the operator. These problems include wellbore instability caused by an unstoppable sloughing of the shale; the experiencing of tight hole conditions while performing the wiper trip; caved shale sticking to shakers while drilling; an increased dilution rate due to mud weight; a low LGS % (low gravity solids), and fluid viscosity. To solve this longstanding drilling challenge, a team formed from operator and service provider experts determined via high-level research and testing the need for an innovative new technology of inhibitive fluid chemistry. After extensive testing, the team determined that a particular environmentally friendly Nano Polymer high-performance water-based mud (HPWBM)—one possessing the unique shale inhibition and cutting encapsulation capabilities capable of stabilizing this sticky shale—was the best fit for this application. We will present the investigational learning and effective field trial drilling of high problematic shale that was evaluated during and subsequently the utilization of nanoparticles (NP) to advance water-based mud (WBM) inhibition properties, proven to offer an eco-friendly Nano Polymer HPWBM substitute with the improved thermal and rheological permanency of the overall WBM formulation. Results will display that while providing more effective drilling and wellbore stability, this technology is also a far cleaner industry alternative.

Wellbore cleaning is a vital link between drilling operations and well completion to secure the massive time and money invested to drill the hole intervals by removing drilling fluids residues, pipe dope, and other debris from the wellbore. The well production can be sustained in the long-term by properly accomplishing this step, promoting technical and operational efficiencies. This paper presents an effective customized treatment design and successful execution of a wellbore cleaning case study. The Wellbore cleaning process is a combination of both mechanical and chemical means, a cleanout string of scraper, brush, magnets, and pill train of surfactants, and solvents are expected to retrieve debris and displace mud residues leaving the wellbore water wet, whose efficiencies can be judged through return fluids Nephelometric Turbidity Unit (NTU) and Total Suspended Solids (TSS). Since different wells vary in geometry, depths, and mud components, a custom design for the wellbore cleaning process is mandatory to guarantee satisfying treatment outputs, the design includes cleanout string parts and spacing, besides solvents and surfactants pills train additives, and volume. Extensive lab testing was performed to customize the proper wellbore cleaning design to remove inverted emulsion fluids (IEF) residues from casing and tubing in the studied challenge gas well. The casing pickling was executed with 150 barrels (bbl) of solvent and surfactant chemical cleaning Spacers containing 630 gallons (gal) of locally manufactured solvent and 378 gal of locally manufactured surfactant displacing the wellbore water with clean water. The water returns NTU and TSS of 47 and 0.03 % Solids respectively were achieved at 179 bbl after the high viscosity tail spacer of the casing pickling. The Cleanout Bottom Hole Assembly (BHA) was subsequently pulled out of the hole free from IEF residues and water wet, demonstrating the good cleaning performance of the locally formulated Chemistries. Similarly, the Tubing Pickling was executed with 54 bbl of Chemical cleaning spacer containing 990 gal of solvent. The water returns NTU and TSS of 38 and 0.02 % Solids respectively were achieved at 168 bbl after the high viscosity tail Spacer of the tubing pickling. In a conclusion, the low NTU and TSS values confirmed the effective wellbore cleaning design and treatment. In this paper, we will be presenting a custom treatment design and successful execution of a wellbore cleaning case study from a chemical perspective, using 100% locally developed chemistries, that are environmentally friendly and readily available in-country, adding the value of lead time and optimized cost to drilling operations, where selected treatments could achieve targeted return fluids NTU and TSS within competitive displacement volume for both casing and tubing.

Extended reach drilling (ERD) has become increasingly more frequent in the petroleum industry as it allows access to additional reserves in oil and gas reservoirs from a single wellbore. Consequently, this has led to an increase in friction related problems while drilling and running casing. This paper describes the extensive lab testing and technical implementation of an innovative technology that utilizes a customized solid lubricant to reduce friction and help operators achieve challenging depths. Comprehensive lab testing was conducted to tailor the required formulations of the solid lubricant and two field trials were completed to evaluate the performance. To properly conduct this evaluation, key performance indicators were established in both wells. A minimum torque reduction value of 10% was targeted for a treatment containing 5 pounds per barrel (ppb) of the solid lubricant. Baseline torque values were captured prior to the lubricant addition and were the benchmark for performance evaluation. Drilling fluid from the active pit was then enhanced with 5-ppb of the solid lubricant and sweeps were pumped downhole to reduce friction. Two extended reach wells were identified in which water-based mud was used to drill. On Well A, at 79-degree inclination high and erratic torque was experienced which affected the drilling performance. Baseline torque was recorded and a sweep with 4 ppb of the solid lubricant was pumped: resulting in a 5.5% torque reduction. After drilling another stand, a second sweep was pumped with 5 ppb concentration and torque was reduced 14.7%. On Well B, at 84-degree inclination high and erratic torque was once again experienced. Baseline torque was recorded, and the first sweep was pumped with 5 ppb of the solid lubricant: resulting in a 10.4 % torque reduction. A second sweep was immediately pumped with another 5 ppb concentration and torque was reduced by 24.3%. In both Well A and Well B, a pill was spotted in the open hole with 8 ppb solid lubricant concentration to assist with the liner run. These field applications successfully demonstrated the concept of this innovative technology to reduce friction and overcome torque challenges in ERD applications; thus, resulting in a drastic reduction in nonproductive time. The industry is continuously looking for opportunities to reduce non-productive time while drilling. This innovative solid lubricant is environmentally safe, compatible in all mud systems, and is highly effective in low concentrations to reduce friction while drilling in some of the most challenging extended reach wells. Minimizing friction and the subsequent torque issues will allow for optimal rates of penetration while drilling in these challenging conditions and thus reduce the overall time constructing the well.

Drilling for Oil & Gas is never an easy task. In order to reach to the hydrocarbon source, several layers of drilling formations with different characteristics need to be drilled through. This leads to a challenge of needing various well designs, tools and fluids to drill these wells. An ideal case would a fluid design that is flexible enough to be applicable for most of the fields; yet providing consistent properties across a wide range of temperatures and pressures. A uniquely customizable flat rheology fluid was developed to meet a variety of conditions in terms of pressures from low density to high density to maintain well control and temperatures from 60 °F at surface to 150 °F - 400 °F range downhole. The fluid constituents were carefully selected to exhibit a flat rheology profile to aid in trouble-free drilling of the well. The fluid also used a novel nanoscale additive to aid in filtration control to enhance filter cake properties in high overbalance situations and minimize the risk of differential sticking which is a large contributor of NPT in drilling operations. The fluid properties were then optimized with typical drilling parameters and well conditions in a robust physics-based hydraulics simulator to ensure successful execution and anticipation of various scenarios. After vetting various formulations in a laboratory setting designed to mimic downhole conditions including contaminants like acid gases; the fluid was ready to be utilized to drill a well in onshore. A holistic plan was utilized to manage all project aspects from resources, logistics, procedures and what if scenarios to allow for a successful implementation of the fluid. The two intervals were drilled ahead of schedule with no NPT or unscheduled events, such as losses or differential sticking despite the fact that one of the intervals had high overbalance of 5,700 psi over the pore pressure. The fluid’s properties were tracked across various temperatures to understand the fluid behavior at different sections of the well where it showed consistently flat rheological profile. The hydraulics simulations showed superior hole cleaning conditions as well as the ability to stay within the narrow drilling window which was confirmed by the trip conditions with no back-reaming and not inducing fractures or experiencing any downhole losses. The fluid performance and consistent fluid properties including rheology, filtration control and suspension of cuttings and weight material with no sag occurrences were enabled by using novel emulsifier chemistry, customized polymeric additives and a novel multi-functional nanoscale additive for high overbalance conditions.

Traditional primary solids control methods use high energy, high G-force shakers to "shake" the fluid off the drilled solids on multiple static screens, and drilling fluid losses are typical 1 barrel of fluid for every 1 barrel of rock drilled. The new approach described in this paper replaces shakers with a vacuum-based system, to optimize the separation of drilling fluid and cuttings as they return from the wellbore. During this trial, a high-flow vacuum and rotating filterbelt (screen) system was configured to safely recover more drilling fluid from the cuttings, with the intention of reduce drilling waste. The goal is to validate the performance and HSE benefits of using vacuum-based primary solids control technology versus traditional shale shakers. Success criteria for the trial on two land wells were compared to common shale shaker performance and included: reduce fluid on cuttings by 30% (no more than 0.7 barrels of mud per 1 barrel of rock drilled); reduce screen consumption; and reduce noise level below that of the existing shale shakers. A third-party cuttings flowmeter was used to measure the rock recovered by the vacuum-based system. The following results were recorded during the trial on two wells: fluid-on-cuttings was only 29%, versus the 70% target for the trial; average filterbelt life exceeded the trial target by 54%; and sound pressure level was measured at 74 dBA, at least 3 dBA less than common shakers. Based on retort analyses, Oil On Cuttings averaged 8.39% wet weight. Total rock recovery for the vacuum-based system was 91% of the theoretical hole drilled. During the fluid/cutting separation process, the unit is operated as an enclosed system, eliminating operator exposure to harmful vapor and gases. Finally, it was noted that changing the filterbelt (screen) could be performed by one person in approximately 3 minutes. In conclusion, the trial demonstrated that 71% less drilling fluid was lost versus a typical shale shaker, at the same time reducing overall drilling waste volumes and providing a safer working environment for personnel. Vacuum-based primary solids control systems represent a step change in performance over the decades-old shale shaker concept. The production of significantly dryer cuttings can eliminate the need for traditional de-sanders, de-silters, centrifuges and cuttings dryers. In addition, benefits related to transportation, storage, and processing of drilling waste, can be dramatically obtained.