Research on the Method of Heat Preservation and Heating for the Drilling System of Polar Offshore Drilling Platform

This study investigates the heat dissipation mechanism of the insulation layer and other plane insulation layers in the polar drilling rig system.Combining the basic theory of heat transfer with the environmental requirements of polar drilling operations and the characteristics of polar drilling processes,we analyze the factors that affect the insulation effect of the drilling rig system.These factors include the thermal conductivity of the insulation material,the thickness of the insulation layer,ambient temperature,and wind speed.We optimize the thermal insulation material of the polar drilling rig system using a steady-state method to measure solid thermal conductivity.By analyzing the distribution of temperature in space after heating,we optimize the distribution and air outlet angle of the heater using Fluent hydrodynamics software.The results demonstrate that under polar conditions,polyisocyanurate with stable thermodynamic properties is selected as the thermal insulation material.The selection of thermal insulation material and thickness significantly affects the thermal insulation effect of the system but has little effect on its heating effect.Moreover,when the air outlet angle of the heater is set to 32.5°,the heating efficiency of the system can be effectively improved.According to heat transfer equations and heat balance theory,we determine that the heating power required for the system to reach 5°C is close to numerical simulation.

Axial Vibration Analysis of the Mud Recovery Line on Deepwater Riserless Mud Recovery Drilling System

The series connection of multistage pumping module is the common concept of deepwater riserless mud recovery drilling system. In this system, the influence of the mass of pumping module on the vibration of mud recovery line cannot be ignored, and the lumped mass method has been utilized to discretize the mud recovery line. Based on the analysis of different boundary conditions, the paper establishes the axial forced vibration model of the mud recovery line considering the seawater damping, and the vibration model analysis provides the universal solution to the vibration model. An example of the two-stage pumping system has been used to analyze the dynamic response of mud recovery line under different excited frequencies. This paper has the important directive significance for the application of riserless mud recovery drilling technology in deepwater surface drilling.

Calculation of the Gas Injection Rate and Pipe String Erosion in Nitrogen Drilling Systems

Detailed information is provided for the design and construction of nitrogen drilling in a coal seam.Two prototype wells are considered.The Guo model is used to calculate the required minimum gas injection rate,while the Finnie,Sommerfeld,and Tulsa models are exploited to estimate the ensuing erosion occurring in pipe strings.The calculated minimum gas injection rates are 67.4 m^(3)/min(with water)and 49.4 m^(3)/min(without water),and the actual field of use is 90–120 m^(3)/min.The difference between the calculated injection pressure and the field value is 6.5%–15.2%(formation with water)and 0.65%–7.32%(formation without water).The results show that the Guo model can more precisely represent the situation of the no water formation in the nitrogen drilling of a coal seam.The Finnie,Sommerfeld,and Tulsa models have different sensitivities to cutting densities,particle size,impact velocity and angle,and pipe string hardness.

Dynamic Analysis of A Deepwater Drilling Riser with A New Hang-off System

The safety of risers in hang-off states is a vital challenge in offshore oil and gas engineering.A new hang-off system installed on top of risers is proposed for improving the security of risers.This approach leads to a challenging problem:coupling the dynamics of risers with a new hang-off system combined with multiple structures and complex constraints.To accurately analyze the dynamic responses of the coupled system,a coupled dynamic model is established based on the Euler-Bernoulli beam-column theory and penalty function method.A comprehensive analysis method is proposed for coupled dynamic analysis by combining the finite element method and the Newmarkβmethod.An analysis program is also developed in MATLAB for dynamic simulation.The simulation results show that the dynamic performances of the risers at the top part are significantly improved by the new hang-off system,especially the novel design,which includes the centralizer and articulation joint.The bending moment and lateral deformation of the risers at the top part decrease,while the hang-off joint experiences a great bending moment at the bottom of the lateral restraint area which requires particular attention in design and application.The platform navigation speed range under the safety limits of risers expands with the new hang-off system in use.

Drilling-based measuring method for the c-φ parameter of rock and its field application

The technology of drilling tests makes it possible to obtain the strength parameter of rock accurately in situ. In this paper, a new rock cutting analysis model that considers the influence of the rock crushing zone(RCZ) is built. The formula for an ultimate cutting force is established based on the limit equilibrium principle. The relationship between digital drilling parameters(DDP) and the c-φ parameter(DDP-cφ formula, where c refers to the cohesion and φ refers to the internal friction angle) is derived, and the response of drilling parameters and cutting ratio to the strength parameters is analyzed. The drillingbased measuring method for the c-φ parameter of rock is constructed. The laboratory verification test is then completed, and the difference in results between the drilling test and the compression test is less than 6%. On this basis, in-situ rock drilling tests in a traffic tunnel and a coal mine roadway are carried out, and the strength parameters of the surrounding rock are effectively tested. The average difference ratio of the results is less than 11%, which verifies the effectiveness of the proposed method for obtaining the strength parameters based on digital drilling. This study provides methodological support for field testing of rock strength parameters.

Optimization of Anti-Collapse Drilling Fluid Systems with High Potassium Content

The ash mudstone in some oil formations is highly water-sensitive.The oil formation is fractured,and the risk of well leakage and collapse is not negligible.This study presents a countermeasure for well collapse prevention,based on a“force-chemistry synergistic balance”approach and the utilization of environmentally friendly and efficient hydration inhibitors.The relevance of this approach is demonstrated considering a drilling fluid system with the high potassium content.The analysis shows that the system can maintain good rheological properties,filtration loss and suspension stability even after aging at 130℃ for 16 h.The primary roll recovery of rock chips is better than 98%.The secondary rolling recovery rate is 89%.The rapid water loss is close to zero.The effects of carrying rock,sand,hydration inhibition and dispersion of drill chips are all noticeable.

Synthetic polymers:A review of applications in drilling fluids

With the growth of deep drilling and the complexity of the well profile,the requirements for a more complete and efficient exploitation of productive formations increase,which increases the risk of various complications.Currently,reagents based on modified natural polymers(which are naturally occurring compounds)and synthetic polymers(SPs)which are polymeric compounds created industrially,are widely used to prevent emerging complications in the drilling process.However,compared to modified natural polymers,SPs form a family of high-molecular-weight compounds that are fully synthesized by undergoing chemical polymerization reactions.SPs provide substantial flexibility in their design.Moreover,their size and chemical composition can be adjusted to provide properties for nearly all the functional objectives of drilling fluids.They can be classified based on chemical ingredients,type of reaction,and their responses to heating.However,some of SPs,due to their structural characteristics,have a high cost,a poor temperature and salt resistance in drilling fluids,and degradation begins when the temperature reaches 130℃.These drawbacks prevent SP use in some medium and deep wells.Thus,this review addresses the historical development,the characteristics,manufacturing methods,classification,and the applications of SPs in drilling fluids.The contributions of SPs as additives to drilling fluids to enhance rheology,filtrate generation,carrying of cuttings,fluid lubricity,and clay/shale stability are explained in detail.The mechanisms,impacts,and advances achieved when SPs are added to drilling fluids are also described.The typical challenges encountered by SPs when deployed in drilling fluids and their advantages and drawbacks are also discussed.Economic issues also impact the applications of SPs in drilling fluids.Consequently,the cost of the most relevant SPs,and the monomers used in their synthesis,are assessed.Environmental impacts of SPs when deployed in drilling fluids,and their manufacturing processes are identified,together with advances in SP-treatment methods aimed at reducing those impacts.Recommendations for required future research addressing SP property and performance gaps are provided.

Chemical modification of barite for improving the performance of weighting materials for water-based drilling fluids

With increasing drilling depth and large dosage of weighting materials,drilling fluids with high solid content are characterized by poor stability,high viscosity,large water loss,and thick mud cake,easier leading to reservoir damage and wellbore instability.In this paper,micronized barite(MB)was modified(mMB)by grafting with hydrophilic polymer onto the surface through the free radical polymerization to displace conventional API barite partly.The suspension stability of water-based drilling fluids(WBDFs)weighted with API barite:mMB=2:1 in 600 g was significantly enhanced compared with that with API barite/WBDFs,exhibiting the static sag factor within 0.54 and the whole stability index of 2.The viscosity and yield point reached the minimum,with a reduction of more than 40%compared with API barite only at the same density.Through multi-stage filling and dense accumulation of weighting materials and clays,filtration loss was decreased,mud cake quality was improved,and simultaneously it had great reservoir protection performance,and the permeability recovery rate reached 87%.In addition,it also effectively improved the lubricity of WBDFs.The sticking coefficient of mud cake was reduced by 53.4%,and the friction coefficient was 0.2603.Therefore,mMB can serve as a versatile additive to control the density,rheology,filtration,and stability of WBDFs weighted with API barite,thus regulating comprehensive performance and achieving reservoir protection capacity.This work opened up a new path for the productive drilling of extremely deep and intricate wells by providing an efficient method for managing the performance of high-density WBDFs.

The Conversion of Non-Dispersed Polymers into Low-Potassium Anti-Collapse Drilling Fluids

Different drillingfluid systems are designed according to mineral composition,lithology and wellbore stability of different strata.In the present study,the conversion of a non-dispersed polymer drillingfluid into a low potas-sium anti-collapsing drillingfluid is investigated.Since the two drillingfluids belong to completely different types,the key to this conversion is represented by new inhibitors,dispersants and water-loss agents by which a non-dispersed drillingfluid can be turned into a dispersed drillingfluid while ensuring wellbore stability and reason-able rheology(carrying sand—inhibiting cuttings dispersion).In particular,the(QYZ-1)inhibitors and(FSJSS-2)dispersants are used.The former can inhibit the hydration expansion capacity of clay,reduce the dynamic shear force and weaken the viscosity;the latter can improve the sealing effect and reduce thefiltrate loss.The results have shown that after adding a reasonable proportion of these substances(QYZ-1:FSJSS-2)to the non-dispersed polymer drillingfluid,while the apparent viscosity,plastic viscosity,structural viscosity andfluidity index under-went almost negligible changes,the dynamic plastic ratio increased,and thefiltration loss decreased significantly,thereby indicating good compatibility.According to the tests(conducted in the Leijia area),the density was 1.293 g/cm3,and after standing for 24 h,the SF(static settlement factor)was 0.51.Moreover,thefiltration loss was reduced to 4.0 mL,the rolling recovery rate reached 96.92%,with excellent plugging and anti-collapse performances.

Digital monitoring of rotary-percussive drilling with down-the-hole hammer for profiling weathered granitic ground

Rock and geotechnical engineering investigations involve drilling holes in ground with or without retrieving soil and rock samples to construct the subsurface ground profile.On the basis of an actual soil nailing drilling for a slope stability project in Hong Kong,this paper further develops the drilling process monitoring(DPM)method for digitally profiling the subsurface geomaterials of weathered granitic rocks using a compressed airflow driven percussive-rotary drilling machine with down-the-hole(DTH)hammer.Seven transducers are installed on the drilling machine and record the chuck displacement,DTH rotational speed,and five pressures from five compressed airflows in real-time series.The mechanism and operations of the drilling machine are elaborated in detail,which is essential for understanding and evaluating the drilling data.A MATLAB program is developed to automatically filter the recorded drilling data in time series and classify them into different drilling processes in sub-time series.These processes include penetration,push-in with or without rod,pull-back with or without rod,rod-tightening and rod-untightening.The drilling data are further reconstructed to plot the curve of drill-bit depth versus the net drilling time along each of the six drillholes.Each curve is found to contain multiple linear segments with a constant penetration rate,which implies a zone of homogenous geomaterial with different weathering grades.The effect from fluctuation of the applied pressures is evaluated quantitatively.Detailed analyses are presented for accurately assess and verify the underground profiling and strength in weathered granitic rock,which provided the basis of using DPM method to confidently assess drilling measurements to interpret the subsurface profile in real time.

Deep-large faults controlling on the distribution of the venting gas hydrate system in the middle of the Qiongdongnan Basin, South China Sea

Many locations with concentrated hydrates at vents have confirmed the presence of abundant thermogenic gas in the middle of the Qiongdongnan Basin(QDNB).However,the impact of deep structures on gasbearing fluids migration and gas hydrates distribution in tectonically inactive regions is still unclear.In this study,the authors apply high-resolution 3D seismic and logging while drilling(LWD)data from the middle of the QDNB to investigate the influence of deep-large faults on gas chimneys and preferred gasescape pipes.The findings reveal the following:(1)Two significant deep-large faults,F1 and F2,developed on the edge of the Songnan Low Uplift,control the dominant migration of thermogenic hydrocarbons and determine the initial locations of gas chimneys.(2)The formation of gas chimneys is likely related to fault activation and reactivation.Gas chimney 1 is primarily arises from convergent fluid migration resulting from the intersection of the two faults,while the gas chimney 2 benefits from a steeper fault plane and shorter migration distance of fault F2.(3)Most gas-escape pipes are situated near the apex of the two faults.Their reactivations facilitate free gas flow into the GHSZ and contribute to the formation of fracture‐filling hydrates.

Design and Implementation of a Control System to Mitigate Osteonecrosis in Orthopedic Bone Drilling Procedures

The drilling process in orthopedic surgery can sometimes lead to an undesired increase in temperature,which can cause serious damage to bones and soft tissues.This overheating is typically identified as a temperature above 47℃,known as the critical limit,and can result in the condition known as osteonecrosis.This study aims to develop a new control system,using a proportional-integral-derivative(PID)controller,to prevent overheating and the resulting osteonecrosis.The bone temperature is constantly measured using a thermocouple and,when it reaches the critical temperature of 47℃,the cooling device is activated by the PID-controlled system.This new control system makes the drill machine with cooling device more user-friendly and allows surgeons to set a desired temperature level manually.

A New Heat Transfer Model for Multi-Gradient Drilling with Hollow Sphere Injection

Multi-gradient drilling is a new offshore drilling method.The accurate calculation of the related wellbore temperature is of great significance for the prediction of the gas hydrate formation area and the precise control of the wellbore pressure.In this study,a new heat transfer model is proposed by which the variable mass flow is properly taken into account.Using this model,the effects of the main factors influencing the wellbore temperature are analyzed.The results indicate that at the position where the separation injection device is installed,the temperature increase of the fluid in the drill pipe is mitigated due to the inflow/outflow of hollow spheres,and the temperature drop of the fluid in the annulus also decreases.In addition,a lower separation efficiency of the device,a shallower installation depth and a smaller circulating displacement tend to increase the temperature near the bottom of the annulus,thereby helping to reduce the hydrate generation area and playing a positive role in the prevention and control of hydrates in deepwater drilling.

Conventional Geothermal Systems and Unconventional Geothermal Developments: An Overview

This paper provides an overview of conventional geothermal systems and unconventional geothermal developments as a common reference is needed for discussions between energy professionals. Conventional geothermal systems have the heat, permeability and fluid, requiring only drilling down to °C, normal heat flow or decaying radiogenic granite as heat sources, and used in district heating. Medium-temperature (MT) 100°C - 190°C, and high-temperature (HT) 190°C - 374°C resources are mostly at plate boundaries, with volcanic intrusive heat source, used mostly for electricity generation. Single well capacities are °C - 500°C) and a range of depths (1 m to 20 Km), but lack permeability or fluid, thus requiring stimulations for heat extraction by conduction. HVAC is 1 - 2 m deep and shallow geothermal down to 500 m in wells, both capturing °C, with °C are either advanced by geothermal developers at <7 Km depth (Enhanced Geothermal Systems (EGS), drilling below brittle-ductile transition zones and under geothermal fields), or by the Oil & Gas industry (Advanced Geothermal Systems, heat recovery from hydrocarbon wells or reservoirs, Superhot Rock Geothermal, and millimeter-wave drilling down to 20 Km). Their primary aim is electricity generation, relying on closed-loops, but EGS uses fractures for heat exchange with earthquake risks during fracking. Unconventional approaches could be everywhere, with shallow geothermal already functional. The deeper and hotter unconventional alternatives are still experimental, overcoming costs and technological challenges to become fully commercial. Meanwhile, the conventional geothermal resources remain the most proven opportunities for investments and development.

Surgical Treatment of Osteonecrosis of the Femoral Head Using Minimally Invasive Surgical Drilling and Cancellous Grafting at Brazzaville University Hospital

Introduction: Osteonecrosis of the femoral head (ONTF) is a debilitating condition. Several treatments have been proposed with controversial results. The aim of our study was to evaluate treatment by surgical drilling coupled with in situ cancellous grafting. Materials and methods: Our study was a case-control study conducted at Brazzaville University Hospital from 1st January 2018 to 31 December 2023. It compared two groups of patients with ONTF: non-operated (13 patients, 20 hips) and operated (22 patients, 35 hips). We used the visual digital scale (VDS) for pain assessment, the Merle D’Aubigne-Postel (MDP) scoring system for clinical and functional assessment, and the evolution of necrosis. Results: The group of non-operated patients had a mean age of 35.69 ± 3.4 years, no improvement in pain with an EVN above seven at the last recoil and a mean global MDP score falling from 12.7 before offloading to 10.13 at one year. The group of patients operated on had a mean age of 37.86 ± 7.02 years, a significant reduction in pain (p = 0.00004) and a significantly increased MDP score (p = 0.0034). A comparison of the two groups of patients showed significant stabilization of the necrotic lesions in the operated patients (p = 0.00067), with better satisfaction in the same group. Conclusion: Surgical drilling combined with grafting in the treatment of early-stage ONTF has improved progress in our series. The technique is reproducible and less invasive. It has made it possible to delay unfavorable progression and, consequently, hip replacement surgery.

Effects of Drilling in Mastoid Cavity over Hearing in the Contralateral Ear

In advanced otological surgeries, powered instruments form an indispensable part. The risk of deterioration to hearing in the operated ear is a commonly discussed issue, however, there remains a possibility of affecting the hearing in the contralateral ear due to transcranial vibration. So in this study we aimed to assess the possibility of the non-operated ear being affected by the noise generated during ear surgeries and whether it is temporary or permanent in nature. Methodology: This study included 63 patients diagnosed with unilateral disease who underwent mastoid surgery. Preoperatively all the patients were subjected to Pure tone audiometry (PTA), Transient evoked otoacoustic emission (TEOAE) and Distortion product otoacoustic emission (DPOAE). Patients were operated using both cutting and diamond burrs of ranging from sizes 1 - 6 mm. Total drilling time was recorded. Results: Post-operative hearing evaluation was done at 1 week, 4 weeks and 12 weeks. The sound emitted by various burrs was recorded by Sound Level Meter. Out of the total 58 patients that followed up, 46 showed change in at least one of the hearing parameters. Patients showing changes had a higher drilling time as compared to those with no changes. Of these, the changes associated with the total drilling time and with cutting burr time were found to be significant. The hearing changes seen on PTA, TEOAE and DPOAE were transient in nature with only one patient having a persistent decreased high frequency threshold at the end of 12 weeks. It was also found that cutting burrs produce more sound as compared to diamond burrs and a larger size burr of a type produces more sound than a smaller one of its type. Conclusion: The drilling of mastoid bone during ear surgeries can transiently impair the hearing in the contralateral ear which is of great significance in patients with only one hearing ear.

Optimized design of drilling and blasting operations in open pit mines under technical and economic uncertainties by system dynamic modelling

Drilling and blasting are the two most significant operations in open pit mines that play a crucial role in downstream stages. While previous research has focused on optimizing these operations as two separate parts or merely in a specific parameter, this paper proposes a system dynamic model(SDM) for drilling and blasting operations as an interactive system. In addition, some technical and economic uncertainties such as rock density, uniaxial compressive strength, bit life and operating costs are considered in this system to evaluate the different optimization results. For this purpose, Vensim simulation software is utilized as a powerful dynamic tool for both modelling and optimizing under deterministic and uncertain conditions. It is concluded that an integrated optimization as opposed to the deterministic approach can be efficiently achieved. This however is dependent on the parameters that are considered as uncertainties.

Treatment of drilling wastewater from a sulfonated mud system

Treatment of drilling wastewater from a sulfonated drilling mud system in the Shengli Oilfield, East China, was studied. The wastewater was deeply treated by a chemical coagulationcentrifugal separation-ozone catalytic oxidation combined process. The factors （i.e. pH value, chemical dosage, reaction time, etc.） influencing the treatment effect were investigated, and pH = 7 was determined as optimal for the coagulation; polymeric aluminum chloride （PAC） was selected as the optimal coagulant with a dosage of 18 g/L; cationic polyacrylamide （CPAM） with molecular weight of 8 million was selected as the optimal coagulant aid with an optimum dosage of 8 mg/L; and the optimal condition of catalytic ozonation was found to be a pH of 12 and an oxidation time of 40 min. The results showed that the combined treatment process was effective. The oil content and suspended solids content of the effluent reached the first class discharge standard according to China＇s standard GB 8978-1996 （Integrated Wastewater Discharge Standard） and the chemical oxygen demand （COD） decreased to 195 mg/L from 2.34×10^4 mg/L after coagulation process and ozone oxidation at pH = 12 for 40 min.

Mechanical analysis of deepwater drilling riser system based on multibody system dynamics

A multibody system including a drilling riser system,tensioners and a floating platform is key equipment for offshore oil and gas drilling.Most of the previous studies only focus on the drilling riser system rather than the multibody system.Mechanical characteristics of the deepwater drilling riser system cannot be analyzed accurately in a simplified model.Therefore,a three-dimensional multibody analysis program is developed.The static and dynamic characteristics of the deepwater drilling riser system under different platform motions are analyzed based on the developed program.The results show that the static displacement of the riser system with tensioners is smaller than that without tensioners,which means the tensioners can suppress the deformation of the riser system.Under surge and sway motions of the platform,the dynamic displacement of the riser system with tensioners is also smaller than that without tensioners due to the tensioner suppression effect.Besides,the heave motion induces a uniform axial vibration of the riser system,while roll and pitch motions excite the riser system to vibrate laterally.Compared with the stress amplitude due to surge and sway motions,the stress amplitude of the riser system due to heave,roll and pitch motions is relatively small but cannot be neglected.