Reverse Circulation Research Articles

Optimization of technological parameters of airlift operation when drilling water wells

Purpose. Development of a methodology for optimizing the technological parameters of the airlift operation, based on the analysis of the pressure balance in the annulus and in the drill string that occurs during drilling. Methodology. The tasks were solved by a complex research method, which includes a review and generalization of literary and patent sources, analytical studies on existing methods for optimizing the technological parameters of drilling with reverse circulation using an airlift. Findings. It has been established that in the study on the airlift circulation method during rotary drilling with reverse circulation, an important role is played by the analysis of the pressure balance arising in the course of drilling in the annulus and in the drill string. It takes into account both hydrostatic pressures and pressure losses for pumping water and water-air mixture. A technique has been developed for assessing the effect of rate of penetration on circulation parameters. Originality. For the first time, it has been shown that the analysis of the pressure balance makes it possible to establish, with a given accuracy, the average effective values of the output parameters: the density of the water-air mixture, its upward flow rate, and the air flow rate at a given velocity of the upward flow of water as it approaches the mixer. Practical value. The proposed technique makes it possible to establish the dependence of the values of the output parameters on the depth of the well, as well as the required compressor performance to provide a given drilling fluid flow rate.

Study on gas desorption law and gas loss estimation in a positive pressure reverse circulation sampling process

The accurate estimation of gas loss is a difficult problem in direct methods for measuring coalbed gas content. When using positive pressure reverse circulation (PPRC) technology to determine gas content, estimating the gas loss of coal samples under positive pressure based on the desorption law under atmospheric pressure may lead to significant errors. To study the gas desorption law in granular coal during PPRC sampling, positive pressure (PP) and positive pressure to atmospheric pressure (PP-AP) gas desorption experiments were conducted, and the gas diffusion kinetic parameters were analysed. The results showed that when the desorption pressure changed from PP to AP, the gas desorption capacity suddenly increased. Under a PP condition, the initial gas desorption rate decreased with increasing desorption PP, which could be expressed by a power function. While the AP initial gas desorption rate increased. Compared to the AP condition, the larger mass transfer resistance Bi and the smaller mass transfer Fourier number F0 in the PP experiments indicated that PP limited the migration of gas in coal particles, resulting in a smaller gas diffusion coefficient. The t model, power model, and logarithmic model were used to analyse the gas desorption data, confirming that existing methods for estimating gas loss have significant errors, and the power model can better describe the PP desorption process. Finally, a device was proposed to avoid pressure changes during sampling and underground desorption analysis. It was verified that using this device, the estimation error in gas loss could be reduced to within 10%. These results can provide guidance for further improving PPRC sampling technology.

Optimum Design of Large-Diameter Reverse Circulation Drill Bit for Drilling Rescue Wells Using Orthogonal Experimental Method and CFD Simulation

Down-the-hole (DTH) hammer drilling with reverse circulation is a novel, mobile, high-speed drilling system suitable for the specific requirements of mine rescue. This technology can be applied to shorten the rescue time during mine accidents. The performance of reverse circulation (RC) drilling depends on the structural design of the drill bit. An orthogonal experimental design is executed to investigate the effect of the structural design parameters of the large-diameter drill bit for drilling rescue wells on the cutting carrying capacity and reverse circulation performance. This study employs computational fluid dynamics (CFD) software to solve the Navier–Stokes equation for three-dimensional steady flow and calculate the flow field around the drill bit to evaluate the RC efficiency. Six key geometric parameters were proven to have a direct influence on the RC performance, including the diameter of suction nozzles Dn, the length of nozzles L, the quantity of nozzles N, the diameter of the pilot hole Dg, the inclination angle of nozzles θs, and the deflection angle of nozzles θd. The CFD simulation experiments were implemented according to the orthogonal array L18(37) and were analyzed using the range, variance, and regression analysis. A mathematical model was developed for the RC efficiency to understand the effect of the factors. The results show that the diameter of suction nozzles Dn has an essential effect on the RC performance of the drill bit. An ideal combination is Dn = 20 mm, L = 50 mm, N = 3, Dg = 50 mm, and θs = 35°, θd = 10°, which was obtained through variance analysis and validated via CFD simulation for higher efficiency. To verify its real performance, a large-diameter RC drill bit with a diameter of 1.2 m was manufactured and tested in the field. The result demonstrated that the drill bit had excellent cutting transport and reverse circulation performance.

Anomaly detection in Fourier transform infrared spectroscopy of geological specimens using variational autoencoders

Fourier Transform infrared spectroscopy (FTIR) is an emerging cost effective and rapid mineralogical characterization technique being applied in the geosciences. Detecting anomalous FTIR spectra is especially relevant to the geoscience domain, as it may indicate abrupt changes in geology or mineralogical composition of the rock sample being examined. Given a large volume of data, detecting anomalies that exhibit significant and abrupt spatial and compositional variability is a time-consuming and challenging task. This paper explores the use of an unsupervised variational autoencoder (VAE) for determining anomalies that may exist within a set of FTIR spectra collected from reverse circulation (RC) drill chip samples spanning several iron ore deposits from the Pilbara region in Western Australia. Diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) were measured from 1,579 two-metre composite samples. Our results showed that the VAE was effective in separating anomalous spectra from spectra typical of unmineralized banded iron formation by leveraging the probabilistic latent representation of the spectra in as few as two latent dimensions. To validate our results, detected anomalous samples were compared with their respective geochemical assays to analyse their mineralogical differences, which may have led to the anomalous spectra. In the iron ore sample data used in this study, the observed spectral anomalies were shown to have elevated concentrations of Al2O3 and TiO2 wt.% while being several standard deviations below the mean Fe2O3 wt.% indicating mineralogies rich in shale as opposed to iron oxide rich mineralogies. While the paper demonstrates the efficacy of the VAE in anomaly detection, it can also be effective in assuring the quality of the FTIR data as a pre-processing step, which is critically important for machine learning applications.

Application of a thermal transient subsurface model to a coaxial borehole heat exchanger system

We present an application of a thermal transient model to a coaxial borehole heat exchanger system. We compare two numerical methods. First, a model with a prescribed formation temperature (PFT); secondly, a method with a modeled formation temperature (MFT). In this comparison, several parameters are analyzed, such as the transient temperature profiles, the heat flux along the wellbore, the overall heat transfer rate, the thermal conductivity of the formation, and the type of flow inside the pipe and annulus — laminar or turbulent. The description of the system by the MFT method is more physically consistent. Then we proceed validating this method against two experimental setups, thereby showing good agreement. We perform a sensitivity analysis to the MFT method, varying the direction of the flow, regular and reversed, and the center tube material, with a high (steel) or low (polyethylene) thermal conductivity. It is shown that the reverse circulation has a better heat extraction, while regular flow performs better in the case of heat injection. For the center tube material, polyethylene shows a better thermal performance when compared to steel.

Assessment on the reverse circulation performance of slurry shield pipeline system assisted with CFD-DEM modeling under sandy cobble stratum

Reverse circulation of slurry shield pipeline system is one of the most effective method to solve slurry chamber clogging during shield tunneling in cobble stratum. In this paper, the assessment on reverse circulation performance of slurry shield pipeline system was performed using the computational fluid dynamics-discrete element (CFD-DEM) coupling approach. In the CFD-DEM coupling model, the shape and size of large irregular cobble particles were considered via 3D scanning technology. In addition, a parametric analysis was conducted, and the effects of the cutterhead rotational speed, slurry inlet velocity and rheological properties of slurry on the reverse circulation performance were investigated respectively. The results indicate that, the magnitude of impact on reverse circulation is in the order of slurry inlet velocity v > slurry plastic viscosity k > cutterhead rotational speed r > slurry yield stress τ0 > slurry power law index n among the working parameters of slurry shield and the Herschel-Bulkley (HB) rheological parameters of the slurry, and the time of reverse circulation is also of importance to the performance of the reverse circulation. Accordingly, a reasonable reverse circulation scheme was suggested, and applied to practical engineering. The findings in this study could provide some references for slurry shield pipeline system reverse circulation of similar projects in the future.

A numerical simulation of dust pollution law under traditional electric rake operation: A case study of Shuiyindong gold mine

The Shuiyindong gold mine in Guizhou is used as a case study in this paper to study patterns of dust pollution occurring with traditional electric-rake operation. In particular, the study uses the northern quarry of the twenty-third line in the first middle section of the second mining area and establishes a three-dimensional simulation model of equal size. It uses Computational Fluid Dynamics (CFD) to simulate and analyse the airflow traces and distribution of dust concentration in the relevant roadway during each stage of the electric-rake operation. The simulation results show that the airflow in the working roadway has a spiral movement and produces reverse dirty-wind circulation towards the end. Dust flows out of the working roadway from the 8th second of operation, and dust concentration reaches a peak in the working roadway at the 12th second of operation at an average dust concentration of 37.5 mg/m³. The dust concentration drops rapidly from the 120th second and reaches the maximum dust concentration permitted for operation at the 180th second of operation. The validity of the simulation is tested by comparing the actual measured data at the site with the simulation results. Finally, the simulation results are analysed using violent Python, and the solution is used to divide the roadway into areas according to the human breathing range. The paper analyses the distribution of dust concentration at an average human breathing height, providing an established theoretical basis for dust-control work in mines.

Simulation on a new reverse circulation fishing tool: Design and evaluation of the salvage capacity and efficiency

AbstractTo solve the insufficient energy for reverse circulation fishing tools in complex structure wells, it is necessary to further optimize the design of the tools to improve the impurity salvage efficiency. In this work, a three‐dimensional (3D) flow field simulation model of reverse circulation fishing tool with venturi negative pressure is employed to identify the vortex zone of circulation channel and to investigate the negative pressure and jet velocity distribution around the spray nozzle based on the ANSYS‐CFX. The effects of the spray angle, diameter of the suction nozzle, and the nonstructural parameters on negative pressure and jet velocity are investigated through sensitivity analysis. As revealed from the results, there may be an optimum value for the spray angle, and the nozzle jet direction can indeed affect the propagation and attenuation of the bottom hole flow field greatly. The combination of the inner diameter of the nozzle outlet and that of the nozzle inlet (Φ + Φ′ = 3 mm + 6 mm) is the best design solution when the negative pressure at the nozzle outlet can be the highest. The negative pressure and jet velocity increase with the increasement of the inlet flow rate. The comparative analysis of different bottom hole impurity mass in the cases of the borehole inner diameter 5′ and 8.5″ on the salvage efficiency are conducted numerically. It is observed that the impurity mass salvaged and salvage time are not directly related to its total amount, but only related to the flow rate of the sucked fluid flow. The impurity salvage efficiency can be as high as 95.4%, which meets the engineering requirements in the field. This work improves the working performance of the reverse circulation fishing tool and provides theoretical guidance for well washing.

On cutting transport for air reverse circulation in horizontal and inclined wells

Air reverse circulation (RC) drilling has drawn considerable interest and has been adopted in tunnel drilling owing to its beneficial features. Cutting transport is a primary concern in RC drilling because poor cutting transport efficiency may lead to several problems, such as stuck pipes, excessive torque and drag, and severe bit wear. The Euler-Euler method of computational fluid dynamics simulation was applied to model the gas–solid two-phase flow in a drill pipe to determine the influence of various parameters on cutting transport. The effects of the air velocity, cutting concentration, rate of penetration (ROP), particle diameter, and inclination angle were investigated by analyzing the variation in the pressure drop, characteristics of cutting motion, and efficiency of cutting transport. The results revealed that the positive contribution of air velocity to transport efficiency was restricted. The optimal concentration of cuttings was approximately 20 %. The pressure drop, average volume fraction, and cutting migration ratio tended to be positively correlated with the ROP. An increase in the cutting diameter led to a decrease in transport efficiency. At an inclination of 30°, the least cutting transport efficiency was observed.

Design optimization of a coal seam annular air reverse circulation bit

AbstractReverse circulation (RC) drilling technology enables the rapid acquisition of coal seam samples, which is crucial in accurately measuring gas content. In addition, the design of the drill bit plays a key role in RC sampling. In this study, the turbulence model and simulation method applied during the RC drilling process is analyzed, and an annular jet flow bit is developed. An experimental laboratory setup is used to simulate the RC performance of the proposed drill bit, based on which an orthogonal design simulation of the structural parameters of the drilling bit studies was performed to investigate the effects of the RC drilling process. The experimental results show that annular jet flow moving up the central channel wall of the bit is conducive to the suction of annular airflow and results in the strong flow field created by the center channel of the bit generating negative pressure in the center channel of the bit, a comparison of the computational fluid dynamics data on negative pressure and suction rate shows that the annular jet flow RC bit is suitable for use in RC drilling.

Modeling of drilling water supply wells with airlift reverse flush agent circulation

Purpose. Determination of the influence of mining and geological conditions of drilling hydrogeological wells with backwash on the technological parameters of the airlift method of cleaning it from drilled rock and the properties of the ascending flow of aerated washing liquids. Methodology. The tasks were solved by a complex research method, including analysis and generalization of literary and patent sources, analytical, experimental studies, using computer and mathematical modeling methods. Findings. An algorithm for the functioning of the airlift circulation method during rotary drilling with backwash has been developed. The algorithm takes into account: hydrostatic and hydrodynamic pressures, and the effect on them of the rate of drilling of the well; the effect of the sludge content in the upstream. The effective values of the airflow rate, the density of the water-air mixture and the velocity of its upward flow are established. A method for estimating the effective values of technological parameters and their changes in the upward flow of the mixture is proposed. A model has been developed that allows analyzing the dependences of the air flow rate, the density of the mixture and the rate of its ascent on the parameters of the well being drilled. The model is applied to typical drilling conditions of a large-diameter water intake well at the Samskoye groundwater deposit on the Mangystau peninsula. Originality. A mathematical algorithm has been developed for the functioning of the airlift backwash method when drilling large-diameter water intake wells. The method is based on the analysis of the pressure balance in the descending and ascending flows of the washing agent. For the case of backwash, a formula for estimating the content of sludge in it was obtained. A method has been developed for determining the average effective density of the mixture in terms of the height of the well, as well as the air content in it. Based on the average effective values, a method is proposed for estimating changes in the density of the mixture, its flow rate and velocity along the upward flow. Practical value. The proposed algorithm is the basis of a computer model that allows you to determine the dependences of the values of the density of the mixture, the content of air and sludge in it and the rate of ascent, from the depth of the well, the depth of the mixer descent, the speed of deepening, the specified velocity of the upward fluid flow, as well as the diameters of the well and drill pipes. Specific modeling results have been obtained in relation to the Samskoye groundwater deposit of the Mangystau peninsula.

Reverse Circulation Displacement of Miscible Fluids for Primary Cementing

AbstractPrimary cementing is the well construction operation where drilling fluid is displaced from the annular space behind the casing string, and replaced by a cement slurry. The annular cement sheath is a critical barrier element that should provide zonal isolation along the well and prevent uncontrolled flow of formation fluids to the environment. We present a combined experimental and computational study of reverse circulation displacement of the annulus, corresponding to operations where cementing fluids are pumped down the annulus from the surface. We focus on iso-viscous displacements in a vertical and concentric annulus, and vary the density hierarchy among the fluids to study both stable and density-unstable displacement conditions. While the interface between the two fluids is advected according to the laminar annular velocity profile for density-stable and iso-dense displacements, considerable secondary flows and fluid mixing is observed for density-unstable cases. Increasing the imposed velocity from the top is seen to provide a certain stabilizing effect by suppressing backflow of the lighter fluid and reduce the magnitude of azimuthal fluctuations. Computational results are in qualitative agreement with the experiments, and support the categorization of the displacement flows as either inertial or diffusive, in accordance with previous work on buoyant pipe displacements.

Assessment of impacts of water transfer on lake flow and water quality in Lake Chaohu using a three-dimensional hydrodynamic-ecological model

Study regionLake Chaohu is a typically large shallow freshwater lake in China, experiencing long-term eutrophication and a short period of drought. Study focusThis study employs a three-dimensional (3-D) hydrodynamic-ecological model to assess the impacts of water transfer on lake flow, water quality, and their relationship, and then reveals optimal strategies for achieving improved water quality in Lake Chaohu. New hydrological insights for the regionResults indicated that clean water transfer could dramatically increase flow rate and decrease nutrient concentrations near the water transfer inlets, while the grade level of lake water quality is not changed. The degree of improvement in water quality parameters is not always proportional to lake flow rate. A clean water transfer through the eastern route (ZH) has the largest improvement effect on the average flow rate and water quality (total nitrogen (TN) and total phosphorus (TP)) of the entire lake. Winter water transfer improves TN and TP better than summer, while the opposite for ammonia nitrogen (NH3-N). Decrease of wind speed is essential for mitigating nutrient accumulation in western lake’s heavily polluted bay through weakening the reverse circulation and the northwest flow. Water transfer operations are revealed to improve water quality in Lake Chaohu: conduct water transfer through ZH in winter, strictly control NH3-N concentration in the donating water, and combine the effects of the low east wind.

Analytical study and field investigation on the effects of clogging in slurry shield tunneling

The pressurized slurry is the essential part of the slurry pressure balanced shield (SPBS) for stabilizing the working face and transporting the excavated soil. If clogging occurs in case of adverse ground conditions or equipment failure, a series of consequences will happen, such as sudden changes in slurry pressure, massive ground loss, and deformation or even collapse at tunnel workface. The present study reviewed and summarized the clogging mechanism of the slurry shield under different ground conditions. Then, based on the law of conservation of mass and Bernoulli’s Equation, an analytical approach was developed to investigate the effects of clogging on the slurry velocity and pressure along with the deformation of tunnel workface. Furthermore, a case study and field measurements were conducted to validate the analytical method. The significant findings drawn from the study can be summarized as follows: (1) The clogging of a slurry shield imposes severe effects on the slurry pressure balancing mechanism of shield tunneling. It can occur in both cohesive and non-cohesive ground with different formation mechanisms. (2) During the initial clogging, the slurry pressure above the spring line increases, and that below the spring line decreases. With the clogging deteriorating, the slurry velocity drops considerably at the top of the deposit area and escalates near the discharging port. The presence and increase of deposit lead to a sharp rise of slurry pressure in the slurry chamber, especially in the clogging region. (3) The reverse circulation of the slurry system (RCSS) is useful to clear the clogging. Still, the slurry deposits at the bottom will obstruct the slurry reverse flow, resulting in inward deformation of the tunnel face and a drastic increase in overcutting volume. (4) The ultimate volume deviation ratio of the slurry was proposed as a useful index to alarm the potential risk of collapse induced by the RCSS. (5) The timely adoption of RCSS is strongly suggested when any abnormal changes in the slurry pressure or the ultimate volume deviation ratio are observed for the first time.

Flow Structure and Short-Term Riverbed Evolution in Curved Flumes

River bending is the major effect responsible for bed topography and bank changes. In this study, fluid velocity (measured by a three-dimensional Doppler advanced point current meter) and bed topographical data have been collected in 40 sections of an experimental model. The whole flume was composed of an organic glass bend, upstream and downstream water tanks, two transition straight sections, a circulation pump, and a connection pipeline. Each section has been found to be characterized by a primary circulation and a small reverse circulation, with some sections even presenting three more or more circulation structures. The minimum circulation intensity has been detected in proximity to the top of the curved channel, while a region with small longitudinal velocity has been observed near the concave bank of each bend, corresponding to the flat bed formed after a short period of scouring. The maximum sediment deposition and scour depth in the presence of a uniform distribution of living flexible vegetation within 10 cm of the flume wall have been found to be smaller than those observed in the tests conducted without vegetation.

Цементирование скважин методом обратной циркуляции. Современный опыт применения

Цементирование скважин методом обратной циркуляции. Современный опыт применения

Study on the Effect of the Water Injection Rate on the Cavern Leaching Strings of Salt Cavern Gas Storages

In the early construction of cavern leaching in salt cavern gas storages, the inner leaching tubing is often blocked, frequently leading to the bending deformation phenomenon of the leaching strings, which can result in out-of-control cavity shapes. It is difficult to monitor the stress, vibration, and morphological changes of the inner tube during the construction of a cavity. There are few research results in this field at home and abroad, and they are limited only to preliminary explorations of the mechanism or summaries and speculation of the field operation. In this paper, an experimental device for testing the dynamic characteristics of salt cavern leaching strings is developed based on the similarity principle. The device is used to simulate two types of operation processes, i.e., the direct and reverse circulation leaching processes. The experimental data are processed using the modal analysis method to obtain the vibration characteristic parameters of the inner leaching tubing in the circulation process with identical flow rates inside the tubing and the annular region. The following main conclusions can be drawn: The circulation mode has no significant effect on the vibration frequency of cavern leaching strings. The deformation characteristics of cavern leaching strings during direct and reverse circulation are identical, featuring maximum deformation at the bottom and minimum deformation in the middle. The maximum deformation of cavern leaching strings during reverse circulation is about 1.5 times that during direct circulation. Through an experimental investigation and analysis, the effects of the water injection rate and the cavern leaching method on the vibration frequency and bending deformation of cavern leaching strings was determined, providing a reference for further solving the bending problem of cavern leaching strings in combination with engineering practice.

Experimental study on vibration characteristics of salt cavern leaching tubing for underground natural gas storage

Leaching tubing is an important tool for building underground gas storage. Its reliability and stability directly affect the building process. However, buckling deformation or fracture often occurs in leaching tubing due to severe vibration. In order to study the vibration characteristics of leaching tubing, a large experimental system is designed. Modal analysis is performed to examine characteristics of leaching tubing. The result of research shows that pressure pulsation of internal turbulence primarily induces the vibration of leaching tubing. Vibration response frequency of leaching tubing is similar to the turbulence pressure pulsation frequency. Meanwhile, amplitude at the bottom and middle of center tube is large. These locations are the risk points of vibration failure and need more attention. Furthermore, the response frequency and amplitude of center tube in reverse circulation are greater than those in direct circulation. Excessive vibration of center tube can be avoided by limiting water injection flow rate and two-port distance. The research results can provide some reference for construction engineers of gas storage and vibration researchers of suction pipe and discharge pipe.

Simulation Study of the Transport Characteristics of the Ice Core in Ice Drilling with Air Reverse Circulation

Ice core drilling with air reverse circulation is a promising technology that uses high-speed airflow to transport the ice core from the bottom of the hole along the central passage of the drill pipe to the surface. Understanding how the ice core moves through the pipe is crucial for this technology in order to calculate the pneumatic parameters. In this paper, experimental study and the CFD dynamic mesh technique are used to analyze the ice core transport process and flow field characteristics. In order to prove the correctness of the dynamic mesh technique, the simulation results were verified with the experimental results, and it was found that all the simulation data were in agreement with the experimental data trend, and the maximum error was less than 10%. According to the study, once the ice core’s velocity reaches its maximum throughout the transport process, it does not change. The ice core’s maximum velocity increases with the diameter ratio and decreases with the length-to-diameter ratio, while eccentricity has no impact on the maximum velocity. When the air velocity reaches 21 m/s, the diameter ratio for the ice core with a length-to-diameter ratio of 2 increases from 0.80 to 0.92, and the maximum velocity increases from 8.92 m/s to 17.45 m/s. Data fitting demonstrates that the equation Vmax=−1.04V0 + 1.04Va describes the relationship between the ice core’s maximum velocity, Vmax, and air velocity, Va. Finally, we obtain the ice core’s suspension velocity model using CFD simulation to calculate the suspension velocity, V0.

Unconventional Bradenhead Cementing in the Delaware Basin Case History

SummaryThis Delaware Basin case history describes a bradenhead cementing method that improves zonal isolation and top of cement (TOC). Common solutions for cementing depleted formations include stage tools, low-density slurries, and reverse circulation. For this bradenhead method, cement is pumped through the wellhead valves and down the annulus to a target loss zone. Field data, laboratory data, and the engineering model support the improvement bradenhead cementing provided across depleted formations.The depleted Brushy Canyon Formation serves as an injection interval for a two-stage bradenhead cement job. This approach isolates formations below the Brushy Canyon with a conventional first stage, while achieving TOC with the second stage pumped down the annulus. Fracture gradients of the injection interval and casing shoe constrain the cement design. To achieve adequate cement placement, the design phase includes the pressure calculations required to start flow and injection for the bradenhead stage. Reactive spacers are utilized to prevent annulus fluid level drop in extreme cases. A benchmarked cement bond log (CBL) quantifies the results and validates this unconventional cementing method.More than 50 two-stage bradenhead cement jobs were executed with a TOC success rate of 100% in intermediate and production hole applications. CBL data obtained after cementing the intermediate casing confirm the two-stage bradenhead as a placement method. In areas constrained by casing shoe pressures, CBL data identified potential areas of shallow injection. These data resulted in a modification of the fluids pumped. Use of these re-engineered fluids reduced injection initiation pressures and improved cement bonding across salt and anhydrite formations. Cementing costs were reduced by eliminating stage tools, annular casing packers, and low-density cement slurries. Pumping the bradenhead job offline (off the rig’s critical path) reduces cost further. These features support bradenhead cementing as an effective solution for wellbore sections with a potential injection zone.The regulatory requirement to place cement above depleted formations resulted in many innovative cementing methods. Stage tools, low-density slurries, and reverse circulation are attempts to avoid formation breakdown, but these methods increase cost and have limited reliability and integrity. Bradenhead cementing takes advantage of the depleted interval to aid in cement placement. Although counterintuitive, bradenhead cementing has proved to be a cost-effective solution that improves zonal isolation and eliminates integrity risks associated with stage tool failures.