Hole Section Research Articles

An Integrated Solution in Utilizing Active Magnetic Ranging to Seal Off Underground Gas Storage: Theoretical Analysis and Field Test

Summary In this paper, we describe a comprehensive technology based on an active magnetic ranging system (AMR) for sealing off the cement plug (CP) in the open hole (OH) section of the wellbore below the existing CP for underground gas storage. Utilizing depleted oil and gas reservoirs for natural gas storage is an important approach toward achieving carbon neutrality. Sealing off old wellbores is prioritized according to relevant standards. The challenge with OHs with CP is that there are no magnetic beacons in the wellbore, and the extent of compaction is unknown. Accurate placement of the seal-off CP is crucial because current technical methods, such as electromagnetic and acoustic waves, have limitations. Magnetic ranging technology, which is mature and widely used for wellbore interceptions or collision avoidance, requires magnetic beacons such as steel casing, drillpipes, or bottomhole assemblies left in the borehole. On the other hand, acoustic positioning techniques are applicable but presently complex to run operationally. In this paper, we propose a comprehensive control technology. It starts by measuring the positional relationship between the subject wellbore (SW) and a magnetic beacon wellbore (MBW) using AMR. The data are then used in combination with additional skew data along with associate positional uncertainty or ellipse of uncertainty (EOU) to determine the location of the target wellbore (TW) and the MBW. By calculating the relative positional relationship between the SW and the TW, OH reentry below CP can be achieved within the EOU below the sidetracking point. After reentry, specific work such as crushing, element logging, caliper logging, and full hydrocarbon gas detection is performed to verify if the TW is still in the original position and if the caprock is properly squeezed and sealed off. The comprehensive technique or method was tested on five wells in the Bohai Bay, successfully assessing the position of the OH wellbore and reentering below the CP. The process system expands the field of AMR and demonstrates significant industrial application value. It provides a new means of sealing off complex old wells.

Effect of the countersunk rivet head dimensions on fatigue behavior of riveted specimens of 2024-T3 alloy

PurposeThis study aims to investigate the effect of countersunk rivet head dimensions on the fatigue performance of the riveted specimens of 2024-T3 alloy.Design/methodology/approachThe relationship between rivet head dimensions and fatigue behavior was investigated by finite element method and fatigue test. The fatigue fracture of the specimens was analyzed by scanning electron microscopy.FindingsA change of the rivet head dimensions will cause a change in the stress concentration and residual normal stress, the stress concentration near the rivet hole causes the fatigue crack source to be located on the straight section of the countersunk rivet hole and the residual normal stress can effectively restrain the initiation and expansion of fatigue cracks. The fatigue cycle will cause the rivet holes to produce different degrees of surface wear.Originality/valueThe fatigue life of the specimens with the height of the rivet head of 2.28 mm and 2.00 mm are similar, but the specimens with the height of the rivet head of 1.72 mm were far higher than the other specimens.

HF/HR VSP acquisition, processing, and interpretation in the deviated section of the high angle geothermal borehole of Grigny GGR5, targeting intra Dogger thin, porous beds.

Defining 5m thin, or even thinner, porous reservoir beds was the feasibility objective assigned to the High Frequency/High Resolution (HF/HR) look ahead VSP survey to be recorded in the deviated section of a geothermal production well drilled down to the top of the carbonate Dogger aquifer in the Paris basin, around 1500m in vertical depth, with a landing angle of 65°. The idea was to predict the depth of the first porous bed(s) to be drilled at high angle, and to determine the minimal DLS (Dog Leg Severity) to be applied by the driller after setting a production casing at the top Dogger level and changing the drilling fluid composition, so as to avoid directional drilling with sharp angles. A 50-100m vertical depth range was targeted for the acoustic impedance to be predicted below the top Dogger carbonate aquifer. Besides, a Pilot Hole (PH) was drilled prior to the high angle leg to assess with full reliability the depth of productive thin beds to be subsequently drilled at high angle. These actions were undertaken within a global R&D project named “SISMOSUB” aiming reservoir characterisation, conducted by the reservoir and drilling engineers of GEOFLUID/GPCIP, in a partnership with IFPEN, and partially financed by ADEME (French Agency for Ecological Transition). High Frequency (HF) VSP still represents a frontier seismic domain to investigate, for which technical difficulties are piling up: First, the surface fix source needs to be extremely repeatable and preferably deliver an increased amount of HF energy to compensate somehow for the higher loss of seismic amplitudes with high frequency. Second, downhole receiver tool or toolstring may not present constant vector fidelity of 3 component reception over the whole recording frequency range, mainly in high frequency, due to mechanical coupling characteristics of the VSP tool hardware and the open borehole ruggedness; in cased hole, the mechanical coupling of the VSP tool to the formation is insured by a good cementing quality between casing and borehole wall. Third, the physics of the seismic attenuation is not fully understood and depends on several factors, mainly viscoelasticity and heterogeneity, potentially variable in depth and laterally to the wellbore. Additionally, the geometrical spreading represents the main factor of amplitude decay, independent from frequency, and can be estimated at processing stage. Surprisingly, the VSP image produced underneath the deviated hole section evidenced a faulted structure. A remarkable abrupt amplitude loss of high frequencies above 120Hz occurs where the direct P-wave ray crosses one of the confirmed minor faults before reaching Total Depth (TD); secondary downgoing arrivals appear locally in depth, mainly in the high frequencies, which are not strictly parallel to the first P-wave arrival...

Enhancing deep orebody prediction and localization through the revelation of geochemical primary halo patterns in drill holes

Geochemical primary halos play a crucial role in mineral exploration as they provide valuable insights into the dispersion of ore materials, identification of concealed deposits, and determination of ore deposit dimensions. The Naruo mining area in the Duolong mineral district, northern Tibet, China well-known for its worldclass porphyry-epithermal Cu–Au deposits is currently chosen as the study area. We employ statistical and nonlinear methods to analyze geochemical data from drill holes. Specifically, R-type cluster analysis is utilized to evaluate element affinity and concentration index, while an improved Grigorian zoning index is employed to delineate the vertical zoning sequence of the primary halo. These methodologies significantly enhance our understanding of element enrichment within geological contexts and greatly contribute to mineral resource evaluation. Based on these results, we have constructed a vertical zonation index model of denudation coefficient tailored to the geological characteristics of mineralization within the study area. This model effectively represents the vertical variation of the ore body. Our findings reveal a decrease in this zoning index towards the central region of deep ore bodies which correlates with deep granodiorite porphyry occurrences. Furthermore, we observe increasing concentrations of Cu, Ag, and Au with depth in specific sections of drill holes indicating promising exploration potential. Supplementary short-wave infrared data suggests the presence of a deep hydrothermal center in drill hole RNZK2404 which tentatively infers concealed porphyry bodies. Notably, the reversal observed at 4200 m on RNZK2404's zoning index hints at a possible hidden ore body at great depths. Finally, three-dimensional visualization techniques effectively illustrate spatial patterns for elements thereby paving way for future endeavors in mineral exploration.

Research on the RZB-Type Three-Dimensional Drilling Strain Measurement System.

Borehole strain gauges play a crucial role in geophysical, seismological, and crustal dynamics studies. While existing borehole strain gauges are proficient in measuring horizontal strains within vertical boreholes, their effectiveness in capturing vertical and oblique strains is limited due to technical constraints arising from the cylindrical probe's characteristics. However, the accurate measurement of three-dimensional strain is essential for a comprehensive understanding of crustal tectonics, dynamics, and geophysics, particularly considering the diverse geological structures and force sources within the crustal medium. In this study, we present a novel approach to address this challenge by enhancing an existing horizontal-component borehole strain gauge with a bellows structure and line strain measurement technology to enable vertical and borehole oblique strain measurements. Integrating these enhancements with horizontal strain measurement capabilities enables comprehensive three-dimensional borehole strain measurements within the same hole section. The system was deployed and tested at the Gongxian seismic station in Sichuan Province. Clear observations of solid tides were recorded across horizontal, oblique, and vertical measurement units, with the tidal morphology and amplitude being consistent with the theoretical calculations. The achieved measurement sensitivity of 10-10 meets the requirements for borehole strain measurement, enabling the characterization of three-dimensional strain states within boreholes through association methods.

Study on flow pattern transition of cuttings transport in extended-reach drilling

Inadequate hole cleaning is one of the major challenges in extended-reach drilling, especially prominent in large-sized hole sections, such as 121/4-in. section. As the drilling parameters including flow rate, ROP and rotational speed change, the cuttings flow pattern converts between fully suspended flow, two-layer flow, and three-layer flow. However, most existing cuttings transport models only study the problem of cuttings transport under a certain flow pattern and do not consider the dynamic conversion of different cuttings flow patterns. Pipe rotation plays a key role in cuttings transport in rotary drilling, but the existing studies have not fully revealed the effect of pipe rotation on the conversion of cuttings transport patterns. In this paper, a stirring diffusion factor is presented to quantify the effect of pipe rotation on cuttings transport, and the mathematical expression of the stirring diffusion factor is obtained through numerical simulations and the nonlinear regression method. Secondly, the critical conditions for the conversion of cuttings flow patterns are obtained by combining mechanical analysis and numerical simulation results, clarifying the applicable scope of different cuttings flow patterns. According to the comparison with experimental results, the prediction error of the new model considering the conversion of cuttings flow patterns is not higher than 11.1%, and the minimum prediction error is only 3.07%. Thirdly, the flow pattern maps for cuttings transport under different drilling parameters are drawn to provide guidance for the identification of cuttings transport pattern and optimization of drilling parameters. Finally, the flow pattern maps are applied to a case study of an extended-reach drilling. The results show that there is a delay effect in the conversion of cuttings flow patterns due to the nonlinear characteristics of annular geometry. Furthermore, the effects of flow rate, ROP and rotational speed on cuttings transport patterns are not independent, but mutually reinforcing and constraining each other. Inappropriate selection of drilling parameters will result in three-layer flow of cuttings transport, and then pipe sticking is likely to occur. The cuttings transport pattern can be converted from three-layer flow to two-layer flow by optimizing drilling parameters, which can significantly improve the hole cleaning effect.

Study on mechanical properties of bolted connection structure of carbon fiber resin matrix composites at low temperature

This article focuses on the impact of low temperature environments that composite materials may face in engineering applications. Through experimental testing, the bearing capacity of carbon fiber resin based composite bolted structures at -100 ℃ and 25 ℃ was obtained, and a continuous damage model (CDM) was established. The damage evolution mechanism of bolted connection structures between metal and carbon fiber resin matrix composites at -100 °C and 25 °C was elucidated through numerical simulation. Research has shown that the ultimate load of the structure at -100 °C is 3.99% lower than that at room temperature, and the failure mode of the composite material structure at low temperature is transverse fracture along the hole edge, which is different from the compression tensile fracture along the nail hole section at room temperature.

Estimation of Surge and Swab Pressures While Tripping for Minimizing Excessive Drilling Problems

Surge and swab pressures result from pipe movement upward/downward during drill string reciprocation and tripping. surge and swab create costly drilling concerns such well kick, formation breakage, and lost circulation. This study aims to find the optimum pipe tripping speed to avoid surge and swab issues, particularly in lost circulation zones. Also, to determine how drilling factors and well bore geometry affect surge and swab pressures. Mud rheology, mud properties, hole diameters, drill pipe diameter, and bottom hole assembly (BHA) dimensions were also analyzed. Dynamic surge and swab model was employed to simulate two case studies in Rumaila Iraqi oilfield. The findings indicated that the tripping speed is the most effective variable on surge and swab pressures. Annular clearance and BHA design have also a major effect on the surge and swab pressures. For the first case study, it is found that whenever the mud weight is far from the pore pressure and fracture pressure gradients, the 5" drill pipe can be tripped in/out of lost circulation formation (Shuaibba formation) at optimum tripping speed of (80 ft/min) without surge/ swab related problems. The reason is that the generated surge pressures (6110-6300 psi) are below the fracture pressure (7100-7400 psi). The results also showed that tripping 5" drill pipe within a maximum running speed of 80 ft/min in (8.5") open hole section through Tanuma formation till Rumaila formation causes a surge pressures of (4650-5050 psi) which is still below the fracture pressures of formations (4750-5660 psi). the results of the second case study (S-shaped well) revealed that the optimum tripping speed of the drill string in the (12.25") open hole through Dammam and Hartha formations is (90 ft/min). it is also concluded that pulling out of hole (POOH) process must be carried out more carefully than the running process since the mud density is near the pore pressure gradient. The results of this study can be further used to improve the drilling efficiency in Rumaila oil field with decreasing non-productive time (NPT) by employing the appropriate tripping speed and optimal drilling operations.

Application of Free Ball Check Valve Mixed Grouting Device

In recent years, due to the uneven water abundance of the aquifer and the complexity of the underground seepage field, the grouting reconstruction project of coal mining enterprises is more difficult. The previous method is to install a high-pressure ball valve before the grouting pipe connected to the grouting pump is connected to the mixing device, which can be manually adjusted when the number of grouting pumps needs to be changed. However, under certain pressure, the ordinary high-pressure ball valve often fails due to the influence of high-pressure mixed slurry, cement solidification and wear, and the number of grouting pumps cannot be increased or decreased in real time. In order to solve the problem that the mixing device of traditional grouting system is easy to fail by using ordinary high-pressure ball valve, the mixing device of free ball check valve was developed and applied in the process of treating the Ordovician limestone aquifer area on the floor of No.9 coal seam in Xipang Well. The practical results show that the pipeline can be automatically closed when a single grouting pump stops grouting, and there is no need to flush the grouting pipeline with a large amount of water, which can improve the grouting efficiency and quality, and the influence time of single hole section is reduced from 8.25h to 0.34h. The process performance can meet the requirements of efficient grouting.

Analysis of Surge and Swab ECD of Herschel Bulkley Fluids in Rumaila Iraqi Oil Field

Surge and swab pressures are frequently produced during various stages of well construction, including casing running and tripping operations. Managing downhole pressure within the mud window is crucial for mitigating the risks associated with drilling operations including wellbore failure, lost circulation, kicks, and well control issues. The primary objectives of this study are to emphasize the theoretical foundation of surge and swab pressures, forecast the optimum pipe and casing tripping speeds, as well as identify the changes in surge and swab pressures (i.e., equivalent circulating density-ECD) for both open-ended and close-ended drill strings. To achieve these goals, a steady state surge and swab model was used to simulate a case study in the Rumaila oil field, located in Southern Iraq, by utilizing landmark-well plan software. The results of this study support the evidence that the string trip speed plays a substantial role in controlling the swab and surge pressures. It was found that pulling out the 5" drill string from the 12 1/4" open hole section drilled with a 9.51 ppg water-based mud at a speed of 10 sec/stand resulted in a swab ECD below the formation pore pressure against all formations, thus resulting in a kick. Moreover, it was found that the annular clearance had a significant impact on the surge and swab ECD whereas the surge ECD at the bit was bigger than that obtained at the previous hole casing shoe. For example, in our case study pulling speeds ranging from 10-190 sec/stand for the 9 5/8" casing could cause the swab ECD to be below the formation pore pressure gradient at total depth (TD), which is 9.23 ppg. While it was safe to run the same casing through the same interval within 55-190 sec/stand. Furthermore, the results emphasized high trip speeds ranging between 10-30 sec/stand, where for close-ended drill strings, greater surge ECD was observed compared to the open-ended ones. The surge ECD of a 5" close-ended drill string at 30 sec/stand (60 m/min) at bit was 9.92 ppg, while an open-ended string at the same speed was 9.9 ppg.

Processing characteristics and ablation mechanism of CMC-SiCf/SiC by rotational thirteen-beam coupling nanosecond laser

Silicon carbide fiber reinforced silicon carbide ceramic matrix composite (CMC SiCf/SiC) has the advantages of high temperature resistance, corrosion resistance, high strength, low density, and oxidation resistance. It is a high-performance advanced material in aerospace, energy and other fields. However, due to its high hardness, brittleness and anisotropy of fiber structure, the research on application-oriented high-quality processing technology has become a hot issue. In this paper, a new process of rotational thirteen-beam coupling nanosecond laser processing of CMC-SiCf/SiC was studied. The rotational thirteen-beam coupling ablation experiments were carried out on CMC-SiCf/SiC workpiece. A laser beam is divided into thirteen beams and rotated around the beam center by using a beam splitter element. The morphology, structure and composition of ablation holes at different speeds were observed and analyzed by laser confocal microscope, scanning electron microscope, and X-ray energy dispersive spectrometer. It is found that the characteristics of rotational beam coupling have a significant effect on the laser ablation morphologies. The results show that the ablation region of CMC-SiCf/SiC is elliptical due to the fast heat transfer of fibers. The energy density distribution of the waist section of the Gaussian like beam after beam coupling is similar to the “W" shape, and the central energy is lower than the surrounding energy, and the ablation holes also show a similar “W" shape. With the increase of rotational speed, the hole depth first decreased and then increased, the hole diameter and roundness first increased and then decreased, and the hole section was “W" shaped. The ablation area can be divided into five parts: the white granular SiO2 solid coverage area, the recast layer, the lower recast layer, the molten layer, and the heat affected zone. The rotational characteristics will make the reaction intensity of the whole ablation area more uniform in the circumferential direction. The formation mechanism and element distribution of each part were explored. The research work in this paper will provide a new technical way for the high-performance application of CMC-SiCf/SiC.

Behaviour of Cold Formed Steel Column with Complex Edge Stiffened Web Openings

Cold-Formed Steel (CFS) sections have gained in popularity due to numerous favourable properties, and with continued research into the various restrictions of such members, their utility in the construction industry has increased dramatically. CFS sections were widely utilised in structural and non-structural applications as they offer lightweight constructions, high strength-to-weight ratios, greater stiffness due to improved sectional profiles, simplicity of installation and assembly, and so on. Optimising these CFS aspects will enable the building of structures at extremely cheap costs. Buckling occurs when the column strength exceeds the cross-section yield. Owing to CFS material characteristics, edge or double stiffeners are used as a best strategy for strengthening the CFS. The primary objective of this research is to examine the strengthening method for CFS G-section columns with edge stiffened hole sections using CATIA software. The results suggest that adding edge reinforced holes to the column enhances its rigidity. The test findings revealed that CFS channel sections with edge-stiffened web apertures had a greater compression resistance than plain channel sections. The G section column with three edge reinforced holes has a low stiffness and utilised as a support element in seismically active structures.

Research on the key technology of Turkish gas storage shaft

The construction procedure of the gas storage well is complicated, and each technical index request is extremely high, does not allow any mistake. The well deviation is difficult to control. Because of the large dip angle of formation, it is difficult to ensure the wellbore quality by conventional anti-deviation measures, and the change of well deviation and azimuth can not be monitored at any time. So it's almost impossible for conventional anti-incline measures to satisfy the design. In the upper large hole section, the tower pendulum bha is used. In the section below the second open hole, the MWD steering system is used to prevent deviation and reduce deviation, and in the second open large hole section, the slim hole is used first, after reaming, the difficulty of deviation control is reduced, the ROP is increased, and the contradiction between wellbore quality and ROP can be solved by using MWD steering system to prevent deviation and straighten, because the casing and the surface casing and the production casing belong to the large diameter thick wall casing, the rigidity is very big, and the casing is also the abnormal oil drilling pipe, this well summarizes the experience, after strengthening the well opening measures, the safe and smooth running.

Geometry perception and motion planning in robotic assembly based on semantic segmentation and point clouds reconstruction

The assembly operations for robots in unstructured environments face tasks with generalized geometric information. The most essential issue for geometry perception is to estimate the relative pose between mating parts and then plan the corresponding actions. Current perception methods mainly focus on template matching of specific parts, which is still lacking in geometric generalization. To enhance the perception generalization ability, we propose an operation framework combining geometry perception and motion planning for robotic assembly manipulation. Semantic segmentation embodies a strong generalization capacity in image processing, which we utilized to extract the geometric features of assembly parts. The networks are trained via a self-made peg-hole image dataset. To reduce the measurement noise, the virtual point clouds for the peg and hole section are reconstructed with semantic mask and camera image principle, and a uniformization algorithm is adopted to raise the quality of the point clouds. The registration is utilized with the noise-free, uniform virtual point clouds, and the relative pose between two mating parts can be estimated more precisely. Also, the sequence of interactive geometry perception actions is defined. The performance of our framework is validated on assembly experiments, including different geometries in and out of our dataset. The results show that the framework proposed in this paper can perceive the generalization of geometry features for assembly parts, and leads to intelligent robotic assembly.

Hole Cleaning during Drilling Oil and Gas Wells: A Review for Hole-Cleaning Chemistry and Engineering Parameters

Efficient hole cleaning during drilling operations is critical to maintain a high rate of penetration and smooth drilling, leading to minimum drilling problems and economical drilling efficiency. This process involves several important factors, including pipe-sticking incidents, higher cuttings concentrations in the annulus, noisy vibration of the drill string, erratic equivalent circulating density, lost circulation incidents, well control incidents, geomechanical hole section instability, tight spots during tripping operations, and excessive usage of chemical additives for conditioning hole sections and mud. Various approaches, including correlations, methodologies, developments, algorithms, equipment, charts, field experience, chemicals, and studies involving experiments, can be used to enhance the efficiency of hole cleaning. The development of hole-cleaning models is important for use as hole-cleaning indicators to ensure optimized drilling efficiency. This paper presents a comprehensive overview of the complex field of hole cleaning in the oil and gas industry. It includes techniques, tools, models, and chemical additives. It also encompasses drilling engineering, operations, and chemistry. To facilitate the transit of drill cuttings, maintain hole section stability, cool and lubricate the drill bit, and transmit hydraulic horsepower, this article outlines the important roles of drilling fluids. The significance of chemical additives, including nanoparticles, natural and modified polymers, and synthetic polymers, in preserving wellbore stability, improving drilling efficiency, and lowering drill bit wear is also covered in the study. It concludes by making recommendations for further study to clarify hole cleaning for the reader to facilitate and boost drilling efficiency.

Visualization of a jet stream group influencing the noise increase phenomena in generated by airflow through a perforated metal plate

The perforated plate is made by a punching process. Because of this manufacturing process, the cross section of holes in a perforated plate varies in the direction of the thickness of the plate. When an airflow passes through a group of holes in a perforated plate, the noise characteristics change depending on the direction of passage. In the case where the cross-sectional area of holes increases in the downstream direction, the aerodynamic noise generated by airflow through holes in perforated plates increases. The cause of the noise increase is considered to be the lock-in phenomenon between the vibration of the plates and the outflow of the vortex. For this to occur, at least seven closely spaced groups of holes are required. In this study, flow visualization using the fog method was performed to clarify the behavior of the jet stream group during the noise increase. The results showed that the vortex outflows at each hole were in opposite phase when the lock-in phenomenon did not occur, but that the vortex outflows at adjacent holes were synchronized when the lock-in phenomenon occurred.

A coupling prediction model of annular pressure build-up for deepwater oil and gas wells during transient-state testing

To accurately predict annular pressure build-up of deepwater high pressure-high temperature oil and gas wells during the transient-state testing, a coupling prediction model of trapped & untrapped annular pressure build-up is proposed. For the short-term process of gas well transient testing, a wellbore transient heat transfer model has been established. Then the improved coupling model of trapped & untrapped annular pressure build-up is established, which is not only novelly considering fluid thermodynamic properties (isobaric expansion coefficient and isothermal compression coefficient) under high pressure-high temperature conditions and annulus fluid mass changes of untrapped annulus, but also considering annulus volume changes. For precise coupling calculating the annular pressure build-up, the annulus is divided into infinitesimal grid cells along well depth. The impact of different considering factors, testing times, testing production rates, formation permeability and cement sheath sealing positions on the annular pressure build-up in the model is investigated. The results show that conventional models (high pressure-high temperature properties and mass changes of the fluid are not considered) will greatly overestimate the annular pressure build-up; as the testing time increases, the impact of untrapped annulus fluid mass changes on the annular pressure build-up will gradually take the dominant role; reasonably optimizing the setting of untrapped annulus open hole section in high permeability formations and increasing the distance between cement sheath and the upper casing shoe can effectively relieve the increasing annular pressure build-up. These findings can achieve accurate prediction of trapped and untrapped annular pressure build-up, and play an important role in guaranteeing the wellbore integrity and safety of deepwater oil and gas wells during transient-state testing.

Creep monitoring and parameters inversion methods for rock salt in extremely deep formation

When underground salt caverns are used for natural gas storage, the pressure difference between the inside and outside of the cavern will cause continuous creep deformation of the surrounding rock. Understanding the creep characteristics and constitutive model parameters of rock salt in actual formations is of great significance for guiding the construction and safe operation of gas storage facilities. In this paper, a creep contraction calculation model for slender cylindrical rock salt caverns was established firstly, based on the theory of complex variables and viscoelasticity. This model can calculate the radial displacement of the surrounding rock at any moment on the cross-section of the rock salt wellbore. Subsequently, two indirect monitoring methods for deep rock salt creep using the open hole section of the well were proposed based on this model, which involves using the cavern pressure change after wellhead closure and the liquid overflow rate after wellhead opening to indirectly reflect the deformation of underground rock salt. These two sets of field experiments can be used together to determine the values of the constitutive model parameters of rock salt creep under actual stress conditions. This theoretical framework was applied in the Ningjin Salt Cavern Gas Storage Project in China. Pressure monitoring was conducted for 150 days, and wellbore fluid overflow was measured for 45 h in a rock salt well at a depth close to 3000 m. The calculated results showed good agreement with the field monitoring data, and the parameters of the Burgers creep model for rock salt under actual conditions were determined. This demonstrates the strong feasibility of the monitoring method and the validity of the computational model. Finally, using the obtained creep parameters, a quantitative analysis of the creep contraction of the wellbore was performed considering factors such as internal pressure, in situ stress, and Poisson's ratio of the rock salt.

Drilling Optimization by Using Advanced Drilling Techniques in Buzurgan Oil Field

Efficient and cost-effective drilling of directional wells necessitates the implementation of best drilling practices and advanced techniques to optimize drilling operations. Failure to adequately consider drilling risks can result in inefficient drilling operations and non-productive time (NPT). Although advanced drilling techniques may be expensive, they offer promising technical solutions for mitigating drilling risks. This paper aims to demonstrate the effectiveness of advanced drilling techniques in mitigating risks and improving drilling operations when compared to conventional drilling techniques. Specifically, the advanced drilling techniques employed in Buzurgan Oil Field, including vertical drilling with mud motor, managed pressure drilling (MPD), rotary steerable system (RSS), and expandable liner hanger (ELH), are investigated and evaluated through case study analyses, comparing their performance to that of conventional drilling techniques. The findings indicate that vertical drilling with mud motor exhibits superior drilling performance and wellbore verticality compared to conventional rotary drilling bottom hole assemblies (BHA) for drilling the 17 ½" hole section. MPD systems employed in the 12 ¼" hole section demonstrate safe drilling operations and higher rates of penetration (ROP) than conventional drilling methods. Rotary steerable systems exhibit reduced tortuosity and achieve higher ROP when compared to mud motor usage in the 8.5" and 6" hole sections. Lastly, investigations of expandable liner hanger cases reveal subpar cement quality in the first case and liner remedial work in the second case, highlighting the successful implementation of ELH techniques in the offset field. Overall, this paper highlights the advantages of utilizing advanced drilling techniques in Buzurgan Oil Field, showcasing their ability to mitigate drilling risks and enhance drilling operations when compared to conventional drilling approaches.

A new real-time hole cleaning monitoring method based on downhole multi-point pressure measurement and data driven approach

During the construction of long horizontal wells and extended reach wells, inadequate hole cleaning can lead to a series of drilling problems. Traditional hole cleaning analysis is simply based on theoretical models or surface vibrating screen data, and cannot accurately assess downhole cuttings distribution and existing problems. This paper introduces a novel research idea that combines the traditional drilling hydraulic model with the artificial intelligence method. A downhole true cuttings distribution technology based on measurement data, the inversion of flow characteristics from pressure in the hole cleaning field, and a new method for quantitatively evaluating the dynamic distribution of downhole cuttings using along-string measurement (ASM) data were proposed. The results depict that, the relationship between hole cleanliness and annular pressure loss in different hole sections under different working conditions is proportional. Second, under given flow conditions, a pressure-driven hole-cleaning model exerted a reverse pressure drop by inferring the effect of cuttings on the borehole. Third, downhole multipoint measurement indicated an accurate evaluation of the hole cleaning condition and provide detailed downhole information that avoided and solve inadequate hole cleaning of long horizontal wells and extended reach wells. In conclusion, the combination of these methods can overcome the defects of traditional hole cleaning analysis. The integrated approach is helpful in improving the practical technique in hole cleaning and promotes the large-scale application in the oil and gas industry.