A New Viscosity and Density Sensing Platform for Drilling Automation

During drilling operations, measurements of drilling fluid/mud viscosity and density provide key information to ensure safe operations (e.g., maintain wellbore integrity) and improve the rate of penetration (e.g., maintain proper hole cleaning). Nowadays, these measurements are still performed manually by using a calibrated funnel viscometer and a weight balance, as stipulated by current American Petroleum Institute (API) standards. In this study, we introduce an automated viscosity/density measurement system based on an electromechanical tuning fork resonator. The system allows for continuous measurements as fast as several times per second in a compact footprint, allowing it to be deployed in tanks or pipelines and/or gathering data from multiple sensors in the mud circulation system. The streams of data produced were broadcasted to a nearby computer allowing for live monitoring of the viscosity and density. The results obtained by the in-tank system in five wells were in good agreement with the standard reference measurements from the mud logs. Here, we describe the development and testing of the tool as well as general guidelines for integration into a rig edge-computing system for real-time analytics and detection of operational problems and drilling automation.

Dynamic Drilling Fluid Invasion Petrophysical Modeling and Corrections in the Presence of Gas Reservoirs - Arab Formation, UAE

Drilling fluid (mud) invasion occurs when the liquid component of the fluid (mud filtrate) invades porous and permeable formations caused by the differential pressure between the wellbore and formation fluids. Changes to the fluid distribution near the wellbore region affects logging tool response, especially those with shallow depths of investigation. The Arab formation in UAE exhibits different degrees of invasion primarily observed in the nuclear and resistivity measurements. This study utilizes tool physics, rock properties, logging time information, and drilling fluid properties, to model invasion corrected log responses and estimate accurate petrophysical properties. Drilling mud filtrate invasion is observed significantly in all wells drilled in the Arab formation in UAE, affecting both wireline and LWD logging tools. Most of the pilot vertical wells appear to be at residual saturations near the wellbore, where drilling mud filtrate invaded deep into the formation and the radial zones near the wellbore are expected to be completely flushed by the filtrate. Drilling mud invasion in the laterals appears to happen early during the drilling phase affecting LWD tool as well, and the measurement becomes function of the time after drilled, affecting mostly nuclear measurements (density and neutron). Clear understanding of the mud filtrate invasion is required to obtain valid petrophysical interpretations. To characterize these effects, two invasion indexes are estimated and used as inputs for the petrophysical model. Results are then validated with the use of Nuclear Modeling and Resistivity Inversion by the use of the SNUPAR (McKeon et al, 1988)(Edmundson, H., and Raymer, L.L., 1979)(Wiley, R., and Patchett, J.G., 1990) and UTAPWeLS (Jesus and Carlos, 2009) (Alberto and Carlos, 2010) (Alberto, Carlos and Bill, 2010) (Shaaban, David, and Carlos, 2017) (David, Joaquin and Carlos, 2019). Individual models are created to evaluate pilot vertical wells and horizontal laterals, as well as pure theoretical models are put forward to demonstrate the importance of performing corrections for mud filtrate invasion, showing the differences particularly in the nuclear responses.

Cutting Re-injection CRI Uncertainty and Risk Assessment

It is the responsibility of oil and gas operators to recycle or dispose of drilling cuttings in a safe and environmentally friendly manner. Environmental regulations are very strict in establishing that green operations and cutting re-injection be as clean and friendly to environment as possible despite the associated challenges and cost. It is the preferred technique by the majority of international companies. Cutting re-Injection operations include grinding down the drilling cutting to small particle sizes and mixing them with a water-based fluid (mud, water, gel) to form a slurry. The slurry is then pumped under high pressure into a disposal formation where fractures can be initiated and propagated. Existing wells can be used as appropriate by targeting watered-out formations far from hydrocarbon- bearing zones; sometimes operators drill new wells purely for cutting reinjection purposes. The main sources of uncertainty include reservoir heterogeneity, permeability, pore throat size and fluid leakoff rates into the formation. The optimum scenario is to pump the cutting re-injection slurry into a very high permeability formation where screening out, plugging or well packing is unlikely, assuming solids are suspended and are completely lost into the formation. This scenario can only be feasible if the formation pore throat size is much larger than the solid size. This paper presents how to conduct risk assessments for all possible scenarios considering all sources of uncertainties. The paper also shows that under some circumstances it is better to pump the cutting slurry into a very tight formation, such as shale (closed system), than a permeable formation with a high degree of uncertainty where screenout potential risk is most likely.

Clear as mud: Clinoform progradation and expanded records of the Paleocene-Eocene Thermal Maximum

The mid-Atlantic coastal plain (eastern United States) preserves high-resolution records of the Paleocene-Eocene Thermal Maximum (PETM) and attendant carbon isotope excursion (CIE), though preservation is highly variable from site to site. Here, we use a dip transect of expanded (as much as 15 m thick) PETM sections from the New Jersey coastal plain to build a cross-shelf PETM depositional model that explains the variability of these records. We invoke enhanced delivery of fine-grained sediments, due to the rapid environmental changes associated with this hyperthermal event, to explain relatively thick PETM deposits. We utilize δ13Cbulk, percent CaCO3, and percent coarse fraction (>63 μm) data, supported by biostratigraphic records, to correlate sites along a paleoslope dip transect. Updip cores from Medford, New Jersey, preserve expanded sections of the initiation of the PETM and the earliest portion of the CIE. Medial sites (Wilson Lake, Millville) preserve an expanded CIE body, and downdip Bass River records the CIE recovery. We interpret this pattern to reflect the progradation of clinoform foresets across the paleoshelf via fluid mud, similar to modern high-sediment-supply rivers and adjacent muddy shelves (e.g., the Amazon, Mahakam [Indonesia], and Ayeyarwady [Myanmar] Rivers). Our subaqueous-clinoform delta model explains the pattern of the CIE records and provides a framework for future PETM studies in the region.

3D Numerical Simulation of Gravity-Driven Motion of Fine-Grained Sediment Deposits in Large Reservoirs

Deposits in dam areas of large reservoirs, which are commonly composed of fine-grained sediment, are important for reservoir operation. Since the impoundment of the Three Gorges Reservoir (TGR), the sedimentation pattern in the dam area has been unexpected. An integrated dynamic model for fine-grained sediment, which consists of both sediment transport with water flow and gravity-driven fluid mud at the bottom, was proposed. The incipient motion driven by gravity in the form of fluid mud was determined by the critical slope. Shallow flow equations were simplified to simulate the gravity-driven mass transport. The gravity-driven flow model was combined with a 3D Reynolds-averaged water flow and sediment transport model. Solution routines were developed for both models, which were then used to simulate the integral movement of the fine-grained sediment. The simulated sedimentation pattern agreed well with observations in the dam area of the TGR. Most of the deposits were found at the bottom of the main channel, whereas only a few deposits remained on the bank slopes. Due to the gravity-driven flow of fluid mud, the deposits that gathered in the deep channel formed a nearly horizontal surface. By considering the gravity-driven flow, the averaged error of deposition thickness along the thalweg decreased from −13.9 to 2.2 m. This study improved our understanding of the mechanisms of fine-grained sediment transport in large reservoirs and can be used to optimize dam operations.

Advances in Maintenance of Ports and Waterways: Water Injection Dredging

The main objective of this chapter is to demonstrate developments in port maintenance techniques that have been intensively tested in major European ports. As regular port maintenance is highly expensive, port authorities are considering alternative strategies. Water Injection Dredging (WID) can be one of the most efficient alternatives. Using this dredging method, density currents near the bed are created by fluidizing fine-grained sediments. The fluidized sediment can leave the port channels and be transported away from the waterways via the natural force of gravity. WID actions can be successfully coupled with the tidal cycle for extra effectiveness. In addition, WID is combined with another strategy to reduce maintenance dredging: the nautical bottom approach, which enables the vessel to navigate through the WID-induced fluid mud layer. The nautical bottom approach uses the density or the yield stress of sediment to indicate the navigability after WID rather than the absolute depth to the sediment bed. Testing WID-based port maintenance requires thorough preparation. Over the years modeling and monitoring tools have been developed in order to test and optimize WID operations. In this chapter, the application of the recently developed tools is discussed.

Machine Learning Applications in Drilling Fluid Engineering: a Review

Drilling fluid (mud) serves various purposes in drilling operations, the most important being the primary well control barrier to prevent kicks and blowouts. Other duties include, but not limited to, maintaining wellbore stability, removing and transporting formation cuttings to the surface, cooling and lubricating downhole tools, and transmitting hydraulic energy to the drill bit. Mud quality is therefore related to most of the problems in drilling operations either directly or indirectly. The physics-based models used in the industry with drilling fluid information (i.e., cuttings transport, well hydraulics, event detection) are computationally expensive, difficult to integrate for real-time analysis, and not always applicable for all drilling conditions. For this reason, researchers have shown extensive interest in machine learning (ML) approaches to alleviate their fluid-related problems. In this study, a comprehensive review of the abundant literature on the various applications of ML in oil and gas operations, concentrating mainly on drilling fluids, is presented. It was shown that leveraging state-of-the-art supervised and unsupervised ML methods can help predict or eliminate most fluid-related issues in drilling. The review discusses various ML methods, their theory, applications, limitations, and achievements.

Rheology of Mud: An Overview for Ports and Waterways Applications

Mud, a cohesive material, consists of water, clay minerals, sand, silt and small quantities of organic matter (i.e., biopolymers). Amongst the different mud layers formed by human or natural activities, the fluid mud layer found on top of all the others is quite important from navigational point of view in ports and waterways. Rheological properties of fluid mud layers play an important role in navigation through fluid mud and in fluid mud transport. However, the rheological properties of mud are known to vary as a function of sampling location within a port, sampling depth and sampling location across the globe. Therefore, this variability in rheological fingerprint of mud requires a detailed and systematic analysis. This chapter presents two different sampling techniques and the measured rheological properties of mud, obtained from laboratory experiments. The six protocols used to measure the yield stresses are detailed and compared. Furthermore, the empirical or semi-empirical models that are commonly used to fit rheological experimental data of such systems are presented. The influence of different factors such as density and organic matter content on the rheological behavior of mud is discussed. The fluidic yield stress of mud samples was observed to vary from 0.2 Pa to 500 Pa as a function of density and organic matter content.