Optimization of Hot-Water Drilling in Ice with Near-Bottom Circulation

Hot-water drilling in ice with near-bottom circulation is more advantageous than traditional hot-water drilling with all-over borehole circulation in terms of power consumption and weight. However, the drilling performance of this type of drill has been poorly studied. Initial experiments showed that drilling with single-orifice nozzles did not proceed smoothly. To achieve the best drilling performance, nozzles with different orifice numbers and structures are evaluated in the present study. The testing results show that a single-orifice nozzle with a 3 mm nozzle diameter and a nine-jet nozzle with a forward angle of 35° had the highest rate of penetration (1.7–1.8 m h−1) with 5.6–6.0 kW heating power. However, the nozzles with backward holes ensured a smoother drilling process and a larger borehole, although the rate of penetration was approximately 13% slower. A comparison of the hollow and solid thermal tips showed that under the same experimental conditions, the hollow drill tip had a lower flow rate, higher outlet temperature, and higher rate of penetration. This study provides a prominent reference for drilling performance prediction and drilling technology development of hot-water drilling in ice with near-bottom circulation.

Intelligent Rotary Steerable System, Coupled with an Instrumented Bit, Delivers Section Plan in Deepwater GOM Project

The challenging offshore drilling environment has increased the need for cost-effective operations to deliver accurate well placement, high borehole quality, and shoe-to-shoe drilling performance. As well construction complexity continues to develop, the need for an improved systems approach to delivering integrated performance is critical. Complex bottom hole assemblies (BHA) used in deepwater operations will include additional sensors and capabilities than in the past. These BHAs consist of multiple cutting structures (bit/reamer), gamma, resistivity, density, porosity, sonic, formation pressure testing/sampling capabilities, as well as drilling dynamics systems and onboard diagnostic sensors. Rock cutting structure design primarily relied on data capture at the surface. An instrumented sensor package within the drill bit provides dynamic measurements allowing for better understanding of BHA performance, creating a more efficient system for all drilling conditions. The addition of intelligent systems that monitor and control these complex BHAs, makes it possible to implement autonomous steering of directional drilling assemblies in the offshore environment. In the Deepwater Gulf of Mexico (GOM), this case study documents the introduction of a new automated drilling service and Intelligent Rotary Steerable System (iRSS) with an instrumented bit. Utilizing these complex BHAs, the system can provide real-time (RT) steering decisions automatically given the downhole tool configuration, planned well path, and RT sensor information received. The 6-3/4-inch nominal diameter system, coupled with the instrumented bit, successfully completed the first 5,400-foot (1,650m) section while enlarging the 8-1/2-inch (216mm) borehole to 9-7/8 inches (250mm). The system delivered a high-quality wellbore with low tortuosity and minimal vibration, while keeping to the planned well path. The system achieved all performance objectives and captured dynamic drilling responses for use in an additional applications. This fast sampling iRSS maintains continuous and faster steering control at high rates of penetration (ROP) providing accurate well path directional control. The system-matched polycrystalline diamond (PDC) bit is engineered to deliver greater side cutting efficiency with enhanced cutting structure improving the iRSS performance. Included within the bit is an instrumentation package that tracks drilling dynamics at the bit. The bit dynamics data is then used to improve bit designs and optimize drilling parameters.

Autonomous Directional Drilling Planning and Execution Using an Industry 4.0 Platform

Today, directional drilling is considered a mix between art and science only performed by experts in the field. In this paper, we present an autonomous directional drilling framework using an industry 4.0 platform that is built on intelligent planning and execution capabilities and is supported by surface and downhole automation technologies to achieve consistently performing directional drilling operations accessible for easy remote operations. Intelligent planning builds on standard planning activities that are needed for directional drilling applications and advances them with rich data pipelines that feed predictive and prescriptive machine-learning (ML) models; this enables more accurate BHA tendencies, operating parameters, and trajectory plans that ultimately reduce executional risk and uncertainty. Intelligent execution provides technologies that facilitate decision-making activities, whether they be from the wellsite or town, by leveraging the digital-drilling program that is generated from the intelligent planning activities. The program connects planning expectations, real-time execution data from the surface and downhole equipment, and generates insights from data analytics, physics-based simulations, and offset analysis to achieve consistent directional drilling performance that is transparent to all stakeholders. This new framework enables a self-steering BHA for directional drilling operations. The workflow involves an automated evaluation of the current bit position with respect to the initial plan, automated evaluation of the maximum dogleg capability of the BHA, and the capability to examine the health of the BHA tools and, if needed, an automated re-planning of an optimized working plan. This is accomplished on a system level with interdependencies on the different elements that make up the complete workflow. This new autonomous directional drilling framework will minimize operational risk and cost-per-foot drilled; maximize performance, procedural adherence, and establish consistent results across fields, rigs, and trajectories while enabling modern remote operations.

Informed Decisions Guided by GeoMechanics to Improve Drilling Performance: A Case Study from Onshore Field, Abu Dhabi; UAE

ADNOC (Abu Dhabi National Oil Company) recently drilled some wells in Onshore Abu Dhabi (Field-A) and encountered consistent hole instability from Umm Er Radhuma (UER) to Simsima. Thus, a GeoMechanical review was proposed to investigate the root causes, if any, and recommend possible remedies for the upcoming drilling campaign. While detailed drilling event analysis allowed to investigate the correlation between the mud weight program and well trajectory, borehole image log analysis and geological understanding from nearby fields indicated the possible role of structural and lithological features on hole instability. Integration of drilling engineering data and regional geological knowledge helped to narrow down the possible causes of drilling challenges. Sedimentalogical review of Image logs have established some correlation between rock types and hole instability events. Drilling experience shows there is very narrow margin for loss and/or gain to occur. There is regional geological evidence of the presence of a wide range of vuggy structures, as well as natural fractures and/or faults. These features tend to make Simsima formation heterogeneous in terms of permeability and more prone to losses. Since most fractures are parallel to SHmax direction and well was drilled towards Shmin direction, there are greater chances of encountering faults and/or fractures, which would be critically-stressed and lead to loss and/or gain situations. Geomechanical parameters helped highlight the magnitudes and orientations of principal stresses. Observations of several tight hole and stuck pipe events while tripping from Radhuma and UERB shale to Simsima seem to indicate mud weight used was insufficient. Role of multiple failure mechanisms was identified, and relevant solutions were recommended as well as implemented to achieve the drilling success. The case study presented here emphasizes how different carbonate textures and the presence and orientation of natural fractures and/or faults within Simsima formation can impact hole instability with respect to wellbore trajectory. Proactive implementation of recommendations from this analysis on well planning and fluid design resulted in improvement of drilling performance and reduction of non-productive time in new wells.

Challenging the Status Quo Leads to Enhanced Drilling Performance

The technology described in this paper has been developed to challenge the shortcomings of the 40+ year old conventional blade stabilizer. The focus of this paper is to compare drilling performance on two lateral well sections against conventional spiral blade stabilizers. The comparison will highlight the noticeable improvement in drilling performance through analysis of relevant drilling parameters. The new design stabilizer, referred to in this paper as Innovative Drillstring Stabilizer (IDS), can be positioned in the drill string as you would typically do with a conventional spiral blade stabilizer or roller reamer. The design, however, is considerably different. The opened profile, placement and contour of the blades are designed to enhance energy transfer and flow along the tool, improving the transportation of cuttings around the tool while minimizing the occurrences of balling up. The orientation and dome shape of the blades is designed to reduce friction and torque, reduce vibration, improve weight transfer and when slide drilling minimizing the occurrence of hanging up and motor stalls. The engineered drillstring stabilizer was deployed in two wells for trial and technology acceptance purpose. An 8" OD innovative drillstring stabilizer was used as part of a steerable motor bottom hole assembly (BHA) in an integrated operations project. An in-depth performance comparison study was conducted by a specialized and independent third party between two identical BHAs. One (BHA-1), however, included conventional spiral blade stabilizers while the other (BHA-2) adopted the innovative drillstring stabilizers. The pioneering design of the IDS in BHA-2 contributed to reducing the overall torque and aiding in better weight transfer and drilling efficiency. It was possible to apply more weight and the energy transfer to the bit, based on mechanical specific energy (MSE) calculations, showed more efficient drilling conditions. As a result, the ROP, both rotating and sliding showed significant improvement with an overall increase of more than 30%. Better stabilization with BHA-2 aided in less vibration and no motor stalls. In addition, while pulling out of hole, lower hook loads were observed due to the enhanced hole cleaning features, improved hole condition and less friction along the string components. When back on surface no indications of balling-up were observed either. Today, drilling related inefficiencies, in the form of low ROP, non-productive time, damages beyond repair or stuck pipe and lost in hole incidents costs the oil and gas industry millions of dollars on an annual basis. The IDS is designed and proved to address such dysfunctions and improve drilling performance and efficiency while simultaneously stimulates a lower MSE drilling environment.

New Intelligent Push-the-Bit Rotary Steerable System Helped Reducing Well Time and Maximized Directional Drilling Performance, Abu Dhabi, UAE

To meet the current oil and gas market challenges, there is an industry need to optimize cost by safely drilling longer horizontal wells to maximize well productivity. Drilling challenges include the highly deviated trajectory that starts from the surface sections and wellhead, the high DogLeg Sevirity (DLS) profile with collision risks, and the thin complex geological structures, especially in new unconventional fields where numerous geological and geomechanical uncertainties are present. To mitigate for those challenges, reviewing the existing drilling techniques and technologies is necessary. To compete in the current Hi-Tech and Automation era, the main challenges for directional drilling service providers are to reduce well time, place wells accurately, and improve reliability, reducing repair and maintenance costs and helping the customer reduce time and costs for the overall project. Offset wells analysis and risk assessments allowed identifying the main challenges and problems during directional drilling phases, which were highlighted and summarized. As a proposed solution, the new generation of intelligent fully rotating high dogleg push-the-bit rotary steerable system has been implemented in the UAE onshore oil and gas fields to improve the directional drilling control and the performance. This implementation reduced the Non-Productive time (NPT) related to the human errors as the fully automation capabilities were being utilized. The new rotary steerable system has the highest mechanical specs in the market including self-diagnosis and self-prognosis through digital electronics and sophisticated algorithms that monitor equipment health in real-time and allow for managing the tool remotely. As a result, the new intelligent RSS was implemented in all possible complex wellbore conditions, such as wells with high DLS profile, drilling vertical, curve, and lateral sections in a single trip with high mud weight and high solid contents. Automation cruise control gave the opportunity to eliminate any well profile issues and maintain the aggressive drilling parameters. Using the Precise Near-bit Inclination and Azimuth and the At-Bit Gamma real-time data and high-frequency tool face measurements in the landing intervals where required for precise positional control to enable entering the reservoir in the correct location and with the correct attitude helping the customer's Geology and Geophysics department to place wells accurately while maintaining a high on bottom ROP.

Drilling Automation – Benefits of the New Drilling Model

A pilot program for automated directional drilling was implemented as a part of the roll out plan in Norway to drill three dimensional wells in an automated mode, where steering commands were carried out automatically by the automation platform. The rollout plan also targeted the use of remote operations to allow personnel to be relocated from the rig location into remote drilling centers. The goal of the program was to optimize the directional drilling performance by assessing the benefits of automation using the latest rotary steerable system technologies and machine learning smart algorithms to predict and manipulated the BHA performance, as well as the ability to predict the best drilling parameters for hole cleaning. The automation was implemented on three different rigs and the data was compared with the drilling performance from the last two years, with three dimensional wells drilled in the conventional method. The main benefits between drilling wells in the conventional method versus drilling wells with the new drilling automation model include the following. Reduce the overall cost per meter – Improve the rate of penetration – Improve running casings Consistence process adherence – Reduce human errors – Reduce POB without sacrificing lost of technical experience Optimize workforce resources – Allows continuity of service (COVID-19 restrictions) Drilling automation can drill smoother wells by reducing the friction factors and tortuosity. This is translated in direct cost savings per meter and reduction in the overall well delivery time, with the advantage of performing the execution and monitoring of the well performance remotely. This new drilling model open the door of new opportunities, especially for the challenges where the work force resources, and drilling performance is a priority for the operations.