The existing American Petroleum Institute (API) equation for internal leak predicts the internal pressure to overcome the pin-box contact pressure generated from the makeup interference plus the energizing effect of internal pressure, which enhances the seal. For threaded connections, internal and external pressures close the connection and increase the leak resistance, whereas axial loads open the

In the process of shale coring, the gas adsorption will increase the flow resistance of gas inside the core, which will inevitably affect the accuracy of shale gas loss. To clarify the underlying effects of seepage flow and related factors during shale desorption, we conducted an experimental study on the influence of methane on seepage resistance of fractured shale and matrix shale under different

The Y basin in the South China Sea has 15 trillion m3 of natural gas and represents typical ultra high-pressure high-temperature (ultra-HPHT) subsurface conditions, with the maximum bottomhole pressure (BHP) of 142 MPa (equivalent density = 2.38 sg), the highest bottomhole temperature (BHT) of 249°C at a depth of 5638 m, and an extremely narrow drilling mud density window. Therefore, there are several

High-torque, low-speed drilling mud motors are typically used to drive rotary-steerable systems (RSS) to improve the rate of penetration (ROP) of the RSS bottomhole assemblies (BHA). Downhole drilling dysfunctions are common when powered RSS BHAs are pushed to the limit for maximum drilling performance. High-frequency (HF) continuous recording compact drilling dynamics sensors were embedded into the

In this paper, we provide some new insights into stick/slip vibration in drilling with polycrystalline diamond compact (PDC) bits. Fifty-six field runs under various drilling conditions were collected with the help of on-bit vibration sensors. Stick/slip vibration occurrence during drilling was analyzed. Two types of stick/slip vibrations were identified: cutting-action-induced stick/slip and friction-induced

In subsea environments, using large-bore/high-rate well designs is often a key contributor to the economic recovery of hydrocarbon resources. Their use is a necessity for accommodating the huge production capacity of the reservoirs they penetrate, with the major benefit of minimizing the number of wells necessary to develop a subsea field. The enthusiasm for using such well designs, however, must also

Automated managed-pressure drilling (MPD) is a method to enhance downhole pressure-control performance and safety during drilling operations. It is becoming more common to use model-based simulation for the evaluation of pressure-control systems designed for MPD automation before using those in the field. This demands a representative hydraulics-simulation model that captures the relevant aspects of

Selecting appropriate proppants is an important part of hydraulic-fracture completion design. Proppant selection choices have increased in recent years as regional sands have become the proppant of choice in many liquid-rich shale plays. But are these new proppants the best long-term choices to maximize production? Do they provide the best well economics? The paper presents a brief historical perspective

Fracture closure and proppant settling are two fully coupled processes during both shut-in and production. Proppant distribution greatly affects the residual fracture width and conductivity evolution, whereas fracture closure might limit proppant settling and force the proppant to crush or embed into the rock. Modeling fracture closure with proppant settling and embedment is challenging because of

Summary The debonding of cementing interfaces caused by perforation will increase the possibility of microannuli/microcrack propagation during hydraulic fracturing. This phenomenon will pose a threat to well integrity not only with stimulation operations but also subsequent long-term production. The objective of this work is to quantitatively investigate the debonding degree of cementing interfaces

During well completion operations, the wells are killed with specific fluids to control the well. These fluids can invade and damage the formation because of fluid/rock interactions. Fluids such as fresh water, brines, and weighted fluids (e.g., barite weighted, calcite weighted, and bentonite weighted) are used to control the formations during completion operations. These fluids can invade and interact

Sand control screens are installed with an internal string (wash pipe) as required which, among other functions, provides a circulation path. In long horizontal wells, running a wash pipe consumes considerable rig time and may limit the ability to reach target depth. In cases in which fluid losses are experienced after screen installation, isolating the open hole with a fluid-loss control valve can

In this study, we perform several tests to develop a formula of glycerol-based drilling fluid that is suitable for shale formations with severe wellbore instability problems. Drilling fluids with varying combinations of nanosilica, glycerol, sodium carboxymethyl cellulose (Na-CMC), and xanthan gum (XG) in organic soil glycerol-based slurry are tested, and the effects of nanosilica on the swelling of

To minimize fluid loss and the associated formation damage, foam is a preferred fluid to perform cleanout operations and reestablish communication with an open completion interval. Because of their high viscosity and structure, foams are suitable cleanout fluids when underbalanced well-cleanout operations are applied. Although several studies have been conducted to better understand foam-flow behavior

Drilling in the offshore environment involves high risk, mainly caused by uncertainties in the reservoir conditions. Unplanned events such as the influx of reservoir fluids (i.e., kick) can lead to catastrophic accidents. Therefore, mitigation of kick is extremely crucial to enhance the safety and efficiency of drilling. In the current study, an unscented-Kalman-filter (UKF)-based estimator is used

Freestanding drilling riser (FSDR), a new type of riser in deepwater drilling, though not in commercial use, can significantly reduce the engineering sensitivity to severe weather compared to the conventional risers. The optimal installation depth of the near surface disconnection package (NSDP) and the optimal number of buoyancy cans are two important parameters in the FSDR system. In this paper,

Separation factor (SF) is a widely used parameter for specifying the safe distance between two wells, and for monitoring safe distance while drilling. A variety of SF formulas is commonly applied in the industry. This paper demonstrates that different SF formulas may give significantly different results when applied to the same scenarios. This may create confusion about the interpretation and validity

Solids found in drilling fluids, particularly weighting materials, can cause significant formation damage by plugging of formation pores. This study investigates formation damage caused by using oil-based drilling fluid systems weighted by micronized ilmenite or micronized barite. Rheological properties of the oil-based-mud (OBM) systems were measured. High-pressure/high-temperature (HP/HT) static

To prevent or minimize problems associated with water coning in horizontal oil producers, inflow control devices (ICDs) are installed along the wellbore to better equalize the toe-to-heel flux. Nozzle-based ICDs are popular because they are easy to model accurately, virtually viscosity independent, and easy to install at the wellsite with many settings. Nozzles can be installed either in the wall of

A significant improvement in deepwater well integrity can be accomplished by deepening the structural casing to have a dual functionality. This exploits the rapid growth of formation strength in the shallow first 1,000–2,000 ft below the seafloor. This first casing string in the deepwater well design would, firstly, support the axial and bending loads of the wellhead, blow out preventers, riser, and

It has often been reported that the peak production of a well drilled in tight formations is highly dependent on the fracture-contact area. However, at present, there is no efficient approach to estimate the fracture surface area for each fracture stage. In this paper, we propose a method to calculate the fracture surface area on the basis of the falloff data after each stage of the main hydraulic-fracture

We propose a novel cement additive made of graphite nanoplatelets (GNPs) for improved hydraulic isolation and durability of oil and gas wells. The primary role of the cement sheath, which is zonal isolation, can be significantly affected by the permeability of set cement (hardened cement slurry). On one hand, it is the inherent microstructural defects of cement, including pores and microcracks, that

Proppant diagenesis occurs when minerals form on the proppant surface and/or around the embedment crater at high-temperature and/or high-stress conditions (Weaver et al. 2005). It has been used recently to explain low fracture conductivity in the field as well as the long-term downward trend of laboratory-measured American Petroleum Institute conductivity data (Liang et al. 2015). However, researchers

This paper provides the technical details of developing models to enable automated stage-wise analyses to be implemented within the real-time completion (RTC) analytics system. The models—two of which use machine learning (ML), including the convolutional neural network (CNN) technique (LeCun et al. 1990) and the U-Net architecture (Ronneberger et al. 2015)—detect the hydraulic fracture stage start

One of the critical issues that occur in many oil and gas wells is the failure of the cement sheath because of debonding from the casing string or from the formation. This results in the formation of microannuli, which can become pathways for fluid migration. Cement shrinkage during setting is regarded as one of the main causes of the formation of microannuli. In this paper, a new class of polymer-based

Most of the test protocols developed to evaluate sand-screen designs were based on scaled-screen test coupons. There have been discussions regarding the reliability of such tests on scaled test coupons. This paper presents the results of tests on wire-wrapped screen (WWS) and slotted liner (SL) test coupons for typical onshore Canada McMurray formation sand. A unique sand control evaluation apparatus

Following uncontrolled discharge during loss of well control events, fracture initiation occurring during the post-blowout capping stage can lead to reservoir fluids broaching to the seafloor. A classic example is Union Oil’s 1969 oil spill in Santa Barbara Channel, where fracture initiation at various locations caused thousands of gallons per hour to broach onto the ocean floor over a month before

As an alternative to cement, the feasibility of bismuth-tin (BiSn; contains 58 wt% Bi and 42 wt% Sn, abbreviations are not in stoichiometric ratio) as a low melting-point plug has been tested by Zhang et al. (2020) for rigless plug-and-abandonment (P&A) service of offshore wells. Similar to BiSn, bismuth-silver (BiAg; contains 97.5 wt% Bi and 2.5 wt% Ag, abbreviations are not in stoichiometric ratio)

Kazakhstan owns one of the largest global oil reserves (approximately 3%). This paper aims at investigating the challenges and potentials for production from weakly consolidated and unconsolidated oil sandstone reserves in Kazakhstan. We used the published information in the literature, especially those including comparative studies between Kazakhstan and North America. Weakly consolidated and unconsolidated

The use of drilling automation is accelerating, mostly in the area of rate of penetration (ROP) enhancement. Autonomous directional drilling is now a high focus area for automating drilling operations. The potential impact is immense because 93% of the active rigs in the US are drilling directional or horizontal wells. The 2018–2019 Drilling Systems Automation Technical Section (DSATS)-led international

Invasion of mud filtrate while drilling is considered one of the most common sources of formation damage. Minimizing formation damage, using appropriate drilling-fluid additives that can generate good-quality filter cake, provides one of the key elements for the success of the drilling operation. This study focuses on assessing the effect of using different types of nanoparticles (NPs) with calcium-

Evaluation of characteristic values of geotechnical parameters (used for oil well design) is associated with uncertainties inherent to the geological processes that change soil strata. Statistical analysis of soil data allows one to deal rationally with these uncertainties. This work addresses some normative recommendations and literature models for statistical characterization of undrained shear strength

Currently, researchers and the industry believe that water invasion into a shale matrix should dominate the process of water soaking before flowback of hydraulic fracturing fluids. Based on laboratory observations with Tuscaloosa marine shale (TMS) cores, we postulate a hypothesis that cracks are formed in shale formations during and after hydraulic fracture stimulation and that they later contribute

The development of exploratory wells is based on the interpretation of seismic readings by geotechnical field experts. Correlation wells, when they exist, are located very far, leading to large uncertainties and to different interpretations by different experts. Exploratory wells are expensive and risky endeavors, in particular deep wells with high-temperature and high-pressure conditions. Reaching

Weight on bit (WOB) and differential pressure (DIFP) are two essential parameters derived from surface sensors during the drilling process. However, there can be significant errors in these measurements due to improper zeroing of these traces. Regular zeroing of WOB is important to ensure that it is calibrated for additional stands that have been added to the drillstring. Similarly, regular zeroing

Accurate and frequent mud checking is essential for optimum drilling operations. Careful measurement and maintenance of drilling fluid properties (density and rheology) maintain the primary well control barrier and optimize fluid hydraulics and hole-cleaning ability. However, a full mud report while drilling is provided only once or twice a day. Moreover, the measurements are mostly performed using

A new model technique is described for comprehensive dynamic stress and displacement analysis of wellbore-completion tubulars, including friction loads with history. A dynamic model of tubing forces is necessary to predict local pipe velocity, which in turn determines the magnitude and direction of localized frictional contact. By tracking dynamic changes in axial force starting from the initial running

Reamers are an integral part of deepwater Gulf of Mexico (GOM) drilling and their performance significantly impacts the economics of well construction. This paper presents a novel programmatic approach to model rate of penetration (ROP) for reamers and improve drilling efficiency. Three field implementations demonstrate value added by the reamer drilling optimization (RDO) methodology. Facilitated

A real-time deep-learning model is proposed to classify the volume of cuttings from a shale shaker on an offshore drilling rig by analyzing the real-time monitoring video stream. Compared with the traditional video-analytics method, which is time-consuming, the proposed model is able to implement a real-time classification and achieve remarkable accuracy. Our approach is composed of three modules:

The authors of SPE-180322-PA [ SPE Drill & Compl 33 (1): 63–76. https://doi.org/10.2118/180322-PA] have submitted corrections to Eqs. 9, 10, 11, A-2, and A-6 of the original paper. The information herein supersedes that in the originally published paper.