Measurement While Drilling Research Articles

Directional Drilling in ‘L’ Profile

Directional drilling is a wellbore along a predetermined trajectory to intersect a designated subsurface target. Directional drilling has a long and interesting history. However, it has only been in the past ten years that much of the new innovative technology has been introduced to meet the challenges of onshore and offshore developments.A typical directional well starts off with a vertical hole and the bottom holes location may end up hundreds or thousands of feet or meters away from its starting point. With the use of directional drilling, several wells can be drilled into a reservoir from a single platform.During the past years many innovations have taken place, including computerized well planning, more use of down hole motors and turbines, techniques to drill horizontal wells and the introduction of Measurement While Drilling (MWD).Directional drilling has now become an essential element in oilfield development, both onshore and offshore. It has made great advances over a relatively short period of time.This work deals with different applications of directional drilling and the deflection techniques used in deviation of the well. Three types of well profiles have also been studied with the designing of BHA (Bottom Hole Assembly) and the synchronization of MWD (Measurement While Drilling) with directional drilling.

An Overview on Measurement-While-Drilling Technique and its Scope in Excavation Industry

Measurement-while-drilling (MWD) aims at collecting accurate, speedy and high resolution information from the production blast hole drills with a target of characterization of highly variable rock masses encountered in sub-surface excavations. The essence of the technique rests on combining the physical drill variables in a manner to yield a fairly accurate description of the sub-surface rock mass much ahead of following downstream operations. In this light, the current paper presents an overview of the MWD by explaining the technique and its set-up, the existing drill–rock mass relationships and numerous on-going researches highlighting the real-time applications. Although the paper acknowledges the importance of concepts of specific energy, rock quality index and a couple of other indices and techniques for rock mass characterization, it must be distinctly borne in mind that the technique of MWD is highly site-specific, which entails derivation of site-specific calibration with utmost care.

New Gyro While Drilling Technology Delivers Accurate Azimuth and Real-Time Quality Control for All Well Trajectories

Summary In response to the increasing demand for a reduction in the uncertainty of wellbore placement to minimize drilling risks and potential liabilities, a new gyroscopic survey tool capable of operating at any attitude during the drilling process has been developed: an all-attitude gyro while drilling (GWD) tool. Gyro survey systems determine the direction of the survey tool in the wellbore, the tool azimuth, by use of measurements of the horizontal components of Earth's rotation in a process known as gyrocompassing or north finding. Current GWD systems are based on angular rate measurements taken about two axes only. These measurement axes are perpendicular to the direction of the wellbore and perpendicular to each other. Although two-axis systems provide accurate estimates of azimuth near vertical, this accuracy degrades as inclination increases, with the azimuth becoming indeterminate because of a mathematical singularity at 90° inclination. To overcome this, an additional rate measurement about the along-hole axis of the tool needs to be performed. Only gyroscopic instruments with three orthogonal sensitive axes, as adopted in the new tool, are capable of measuring the full horizontal Earth rate signal in all wellbore geometries. This paper describes a number of innovative technological developments that have allowed all-attitude GWD to become a reality, including a new gyroscope designed specifically for the downhole drilling environment, a new system mechanization to control gyroscope biases, a signal-processing technique known as continuous adaptive processing that estimates the g-sensitive bias errors at each gyrocompass station, and a more robust quality control scheme. The new high angle GWD system is well-suited to handle any wellbore-placement needs. These include high inclination kickoffs, infill drilling, relief wells, and the provision of improved accuracy in east/west wells. With the improved reliability of the data comes increased confidence that the resulting survey is representative of the true wellbore trajectory. The detection of gross errors can also be accomplished by comparing real-time GWD and measurement-while-drilling (MWD) data. Further, with the memory multishot capability that is available, reliable high accuracy surveys from section total depth (TD) to surface are generated, verifying both MWD and GWD performance on the trip out and eliminating the need for separate and rig-time-dependent gyroscopic surveys. Finally, a number of case studies are presented to illustrate the performance capabilities of the new gyroscopic system over a range of well trajectories and latitudes. The all-attitude GWD system not only allows the survey-reliability goals to become a reality in a cost-effective manner—as set out in the earlier quality control papers published in conjunction with the SPE Well Positioning Technical Section—but also does this in real time while drilling.

Improved Continuous Azimuth and Inclination Measurement by Use of a Rotary-Steerable System Enhances Downhole-Steering Automation and Kickoff Capabilities Near Vertical

Summary When kicking off at low inclination, static measurement-while-drilling (MWD) surveys are used to confirm the kickoff direction, when free of magnetic interference from offset wells. However, because MWD continuous azimuth and inclination measurements have limited accuracy when near vertical, the directional driller does not have confidence in the kickoff direction with continuous (dynamic) survey while drilling. This requires additional static surveys to be made, taking up rig time. In a novel continuous survey method used in a particular rotary-steerable system (RSS), a six-axis survey was taken continuously, both while drilling and when static, with the survey sensors being housed in a rotation-speed-controlled platform in the RSS. This algorithm was first verified in a software simulator, and it was subsequently implemented in hardware and tested in a hardware-in-the-loop (HIL)-simulator environment. The effectiveness of the new measurement method was field tested and compared with MWD static survey points. The field-test result shows that the new near-bit continuous azimuth and inclination measurement from the RSS is considerably more accurate than the MWD continuous measurements at very low inclinations less than 5°. The new survey method not only provided more-accurate kickoff from a near-vertical position but also enhanced the automated-vertical-drilling feature. In addition, improved continuous measurements around magnetic north and south allowed the closed-loop attitude-hold algorithm of the RSS to drill lateral sections more precisely in these directions. This unique measurement method has valuable applications, such as low-angle kickoff without the use of multiple static surveys because the directional driller can use the continuous azimuth and/or tool face to accurately steer the well. Equally important is that if gyro surveys are required, their number will reduce when the survey-measurement point is so close to the bit, reducing the amount of time of exposure to magnetic interference from an offset casing. When drilling out of the shoe, this survey method will allow an accurate kickoff approximately 50 ft earlier than would normally be expected when magnetic interference is cleared. In addition, the use of a continuous gravity tool face (GTF) is possible without the need for static surveys, allowing accurate low-side sidetracks to be performed even in areas of high magnetic interference. This surveying method reduces the rig time needed to kick off and provides a more reliable real-time measurement for the directional driller to ensure that the desired well trajectory is drilled through crowded platform environments.

Wired-Drillpipe Technology in a Deep Ultradepleted Reservoir

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 163501, ’Using Wired-Drillpipe Technology During Managed-Pressure-Drilling Operations To Maintain Direction Control, Constant Bottomhole Pressures, and Wellbore Integrity in a Deep, Ultradepleted Reservoir,’ by John Rasmus, SPE, Alain Dorel, Tony Azizi, Andre David, Ember Duran, Hector Lopez, Gare Aguinaga, Juan Carlos Beltran, and Antonio Ospino, Schlumberger, and Eduardo Ochoa, NOV IntelliServ, prepared for the 2013 SPE/IADC Drilling Conference and Exhibition, Amsterdam, 5-7 March. Wells drilled with nitrified drilling fluids require a solution for the transmission of measurement-while-drilling (MWD) surveys, bidirectional communication with rotary-steerable systems (RSSs), and transmission of MWD and and logging-while-drilling (LWD) measurements of downhole temperature and annular pressure for surface choke adjustments. Results from a well recently drilled into an underpressured reservoir in southern Mexico provided an opportunity to demonstrate the applicability of wired drillpipe (WDP) to deliver the required measurements and maintain the proper directional control while keeping the well fluids under control. Introduction This paper describes how WDP and managed- pressure drilling (MPD) enabled an operator to drill a severely depleted reservoir with an inverse-emulsion mud mixed with nitrogen delivered through a drillpipe-injection system. This field has a complex structure divided by a salt intrusion into northern and southern portions. Six reverse faults oriented in different directions are involved in this structure. The reservoirs are found in the Middle and Lower Cretaceous and in the Kimmeridgian-Jurassic. Initial production was from the Lower Cretaceous interval, which is now below saturation pressure. The reservoir pressure has declined dramatically, making it necessary to provide a gasified fluid system to avoid lost-circulation problems while drilling.

Research on MWD Mud Pulse Signal Waveform Identification Algorithm

Measurement while drilling (MWD) technology uses mud pulse signals in real-time observation bottom of the relevant data, the decoding system on earth will detect and recognize the information received from the shaft bottom. It is one of the core technology of MWD. However, there are all kinds of noise that exsit in the signal channel will create interfere of signal transmission with the date identification error .This article first offer a new way based on the analysis of the Manchester mud pulse signal noise code and attenuation model. At the same time it used NLMS(Normalizod least mean square) adaptive filter algorithm to wipe the pump noise and other interferences .It can more effectively decrease the influence by pump pulse base-value. Due to the features of mud pulse, we apply the waveform identification algorithm to the recognize research after get the data. Finally, field test results showed that the waveform identification algorithm can recognize the mud pulse correctly and the decoding process is easier, higher reliability, lower ber by the field test. All these comply with the requirements of the engineering application.

Research on Manchester Coded Mud Pulse Signal Extraction

The mud pulse signal extracting in MWD(Measurement while drilling) was a core technology in the oil drilling developing process. In terms of the extraction and recognition problems of weak mud pulse signal in MWD, this paper analyzed the transmission format of Manchester coded down-hole datum and transmission characteristics of mud pulse signal and used morphological filtering algorithm to extract the mud pulse signal. According to the characteristics of the Manchester coded underground synchronization signal. After determining the location of the signal start time, It proposed a pattern similar waveform-recognition algorithm to detect the mud pulse signal. The field tests show that the algorithm can accurately define the mud pulse signal starting time and can effectively improve the decoding accuracy and meet the requirements of engineering applications.

Compressive Strength Analysis of MWD Microchip Tracer

Pressure resistant performance of Measure While Drilling (MWD) microchip tracer to withstand the harsh downhole environment is one of the key issues of normal working. Therefore, it is an effective way to analyze pressure resistant performance of the tracer in the design phase. Compressive strength of the tracer was studied based on finite element method. Considering downhole complexity and working conditions during the processing of tracer roundness, material non-uniformity and other factors. In this study, researchers took sub-proportion failure criterion to determine the failure of tracer. Simulation results of two structures, with pin and without pin, show that both structures met the requirement of downhole compressive strength, and the structure with pin was better than the structure without pin. This study provides basis for downhole application of microchip tracers.

Research on Mud Pulse Signal Starting Time Extracting Algorithm in MWD

The mud pulse signal extracting in MWD(Measurement while drilling) was a core technology in the oil drilling developing process. Determining how to accurately define the mud pulse signal starting time was a key issue affecting the decoding accuracy. This paper analyzed the transmission format of down-hole datum and transmission characteristics of mud pulse signal, using a wavelet multi-scale and related de-noising algorithm to extract mud pulse signal. On this basis, according to the characteristics of the underground encoded synchronization signal, It proposed an algorithm based on equal segmentations within a signal period to define the mud pulse signal starting time .The field tests show that the algorithm can accurately define the mud pulse signal starting time and can effectively improve the decoding accuracy and meet the requirements of engineering applications.

Identification and ranging of reservoir boundary in horizontal wells geosteering

Abstract To make quantitative measurement of the distance between the drilling tool and the reservoir boundary in horizontal well drilling, this paper presented the method of “layer-detection ranging”, established the physical and mathematic models and designed the circuit supporting the method. Moreover, the simulation experiment was made to verify the method's feasibility. With the method, the reservoir boundary was detected and the distance between it and the drilling tool was measured through transmitting directional high-frequency electromagnetic waves and receiving reflection waves, in process of measurement while drilling (MWD) in the horizontal well drilling. Two “layer-detection ranging” circuits, i.e. high-voltage narrow pulse and single frequency modulating pulse, were designed. Based on the circuit theory, a “layer-detection ranging” system was established and three media were used for simulation experiment. The results show that: more details of the reservoir are acquired from received waveforms using the high-voltage narrow pulse circuit, and the received waveforms are more easily identified and discriminated using the single frequency modulating pulse circuit; under the conditions of different media and distances, the relative error between the true distance and the distance measured with the “layer-detection ranging” method is less than 5%, suggesting that the method is reliable.

Orientation Method Simulation in Twin Parallel Horizontal Wells

As traditional measurement while drilling (MWD) method cannot meet the high reliability, high precision requirements for drilling complex structure wells. A guided-orientation method based on rotating magnetic field has prominent advantages on the twin parallel horizontal wells and can apply in twin parallel horizontal wells. In this paper, RMRS, namely Rotating Magnet Ranging system, its operating principle was gave firstly while applied for drilling twin parallel horizontal wells. The rotating magnetic sub was characterized by a pair of orthogonal magnetic dipoles, and then build the model for positioning the twin parallel horizontal wells Finally, the authors used the Maxwell software to simulate the algorithm based on the scene environment, and then proves that algorithm is correct and useful for guiding the well to drill and keeping the twin wells parallel.

Animation Design and Production of Kilometer Directional Drilling Technology and Equipment

Combined with the Measure While Drilling (MWD) system of the new kilometers directional drilling rig and the method of directional drilling technology, this paper uses animated video technology of product to simulate the major workflow and the actions of whole technology and equipment which used to construct drilling hole for gas drainage in the coal mine, and the production of the animated videos make the related personnel establish the full visual impression in the practical application course of whole directional drilling technology and equipment, and it also could be used for the propaganda of related technology products and personnel technical training, and help to promote the application of this technology.

230°C Accelerometer with Digitized Output for Directional Drilling

Measurement-While-Drilling (MWD) technology for oil and gas, and geothermal directional drilling exploration is pushing into ever higher temperature environments - beyond 200°C. Orientation sensors supporting these high temperature environments need to provide highly accurate elevation and tool face measurements on the order of 0.1°. Honeywell has developed a new digital high temperature down-hole accelerometer, DHTA230, capable of providing the required accuracy at the elevated temperatures of 230°C, in the rugged MWD shock and vibration environment, with expected excellent reliability and life. The DHTA230 is designed for use in the downhole environment, but is based upon a mature Honeywell accelerometer using dual vibrating beam sensing elements. These sensing elements are configured as double-ended-tuning-forks in a push-pull orientation attached onto a pendulous proof mass. This push-pull configuration provides an acceleration signal proportional to the frequency difference of the vibrating beams, an easily captured digital signal through measurement of the two vibrating beam phases. The digitized accelerometer eliminates the need for A/D electronics in the high temperature drilling environment. The DHTA230 is 0.79” in diameter with a depth of .393” at the mount flange. The ruggedized configuration of the DHTA230 is expected to provide reliable orientation measurement in high temperature direction drilling applications up to 1000h. The DHTA230 electronics incorporate ceramic hybrids with chip and wire construction. Active die are based upon proven 300°C chips developed previously for the Enhanced Geothermal Systems OM300, fabricated using Honeywell HTSOI4 process. The electronics include power conditioning providing reliable operation using a single power supply between 7V and 15V. Dual oscillator electronic circuits provide the necessary function to drive and sense the dual vibrating beams, while providing a CMOS logic level signal of the frequency pulse train. The accelerometer provides precision output up to 15g acceleration inputs, and allows sensing of higher-g vibration levels. This paper contains information on the target application, electrical and mechanical component requirements, design, fabrication approach, and initial prototype testing. The DHTA230 is expected to enter production transition in 2015.

Application of rotary geosteering drilling in deep and thin reservoirs of Tarim Basin, NW China

Abstract Geological features, such as deep and thin reservoirs and unstable structure margin, occur in an oilfield of the Tarim Basin. To deal with these problems while drilling, a rotary geosteering drilling technique was introduced. The effect of its application was analyzed with an example, the shortcomings were summarized, and suggestions were given for other oilfileds. The feasibility and necessity of using rotary geosteering drilling were presented according to the engineering challenges in the oilfield, then the theory and main tools of it were introduced. Focusing on a double-step horizontal well in field application, the features and effects of this technique were elaborated. With rotary geosteering drilling in this well, the average rate of penetration was high and oil reservoir encountering rate was up to 82% in thin layers less than 1 m. Also, it avoided effortless weight on bit in sliding drilling method and made the wellbore more smooth and clean. The problems met were concluded, for example, the tools build-up rate was affected by several factors, measurement while drilling (MWD) signal was interfered, and the tools working performance was unstable. Suggestions were put forward for applying the rotary geosteering drilling technique in other oilfields.

Successful Cases of Horizontal-Well Tight-Sand-Gas Development in China

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper IPTC 16824, ’Challenges of Horizontal Wells and Successful Cases for Tight- Sand-Gas Development in China,’ by Jia Ailin, He Dongbo, Jia Chengye, Ji Guang, and Wei Yunsheng, PetroChina, prepared for the 2013 International Petroleum Technology Conference, Beijing, 26-28 March. The paper has not been peer reviewed. Three observations have resulted from horizontal-well development in the Sulige tight gas field. First, well-location selection should be influenced by detailed geological research. Second, measurement while drilling (MWD) is the most effective technique in enhancing the drilling success rate. Third, stimulation treatments such as multistage hydraulic fracturing are the most effective way for gas wells to increase their deliverability. Introduction Tight sand gas, one of the main types of unconventional gas reservoirs, displays the most rapid development worldwide in recent years, especially since its successful development in the US. Tight gas resources are estimated to be 10 trillion m3 in China alone. China holds a large amount of tight-sand gas resources and has obtained good performance in exploration and production during its 11th Five-Year Plan period. The Sulige gas field in the Ordos basin, the Xujiahe gas field in the Sichuan basin, and the Denglouku gas fields in the Songliao basin all show typically successful exploration and production of tight-sand gas in China. Compared with geological settings and development backgrounds in North America, tight-sand gas in China has differing characteristics, including poorer original gas in place, increased depth, and lower netpay thickness. For tight-sand-gas development, low economic benefits are the main control factor. High costs in drilling, completion, and fracturing, coupled with low revenues from wellheads, scare investors away. From a technical perspective, low saturation, low production rate, and low estimated ultimate recovery (EUR) are constraints. Thus, technical innovations to improve production level and EUR are necessary. For tight-sand gas in the US, infill drilling was the predominant development strategy in the 1990s. For tight gas wells, drainage areas are usually small, the result of reservoir heterogeneity and poor petrophysical properties. Thus, infill drilling can effectively release the remaining gas left by the primary well pattern. The consequences for infill drilling include more gas derived from the reservoir and more costs associated with drilling and completion. In recent years, horizontal drilling and hydraulic fracturing, especially staged fracturing, have become more frequent. Compared with vertical wells, horizontal wells have the advantage of greater drainage area, which can effectively increase the EUR. Staged fracturing can effectively improve the flow matrix and can increase the production rate; thus, the two main factors causing poor economic benefits and constraining tight gas development can be effectively resolved.

Applications of Mud Pulse MWD/LWD System in Bakken Formation, North Dakota, USA

10,000 ft horizontal drilling and hydraulic fracturing with 24 to 36 stages are prominent in Bakken petroleum system with great success. Although advanced automated drilling system with cutting edge comprehensive logging units are available from service providers to obtain various data assisting comprehensive real-time analysis, conventional positive displacement motor (PDM) with mud-pulse (MP) measurement while drilling (MWD)/logging while drilling (LWD) system is still widely applied in this area to steer and navigate the well bore in pay zone with cost-effectiveness and efficiency. In this paper, several field cases for MP MWD/LWD systems will be discussed and lessons will be summarized to help optimize rate of penetration (ROP), reduce non-productive rig time, and improve operators drilling practices.

Downhole Measurement and Monitoring Lead to an Enhanced Understanding of Drilling Vibrations and Polycrystalline Diamond Compact Bit Damage

Summary Since backward whirl was discovered as a severe cause of polycrystalline diamond compact (PDC) bit failure, the oil and gas industry has made great strides toward creating whirl-resistant bits and operating practices. But is whirl still the major cause of PDC bit damage in conventional rotary applications? This paper reports on a recent field study in which downhole vibrations were measured by use of a newly available in-bit vibration-monitoring device. The focus of this study was to understand the primary source of bit damage. In addition, four wells were also drilled by use of a research drilling rig in Oklahoma. In these tests, the PDC bits, bottomhole assemblies (BHAs), and operating parameters were varied to document their effect on downhole vibrations. In these four wells, vibration measurements from the new in-bit measuring device were validated against a commercially available and industry-proven measurement-while-drilling (MWD) vibration-monitoring service. The results of this study indicate that the most common field vibration in hard-rock vertical conventional rotary drilling is stick/slip, not whirl. In field tests, stick/slip was observed almost exclusively. For typical field applications with a surface rotary speed of approximately 70 rpm, the team measured a peak downhole rpm as high as 500 during the slip phase. Stick/slip was identified as the primary cause of bit damage in these applications. Lateral vibration occurring during the slip phase correlated well with the observed damage and is proposed as a new mode of damage during stick/slip. The characterization of the lateral vibrations coupled with stick/slip is presented on the basis of downhole measurements.

Analytical Model To Predict the Effect of Pipe Friction on Downhole Fluid Temperatures

Summary The advent of deviated, horizontal, and extended-reach drilling has led to increased frictional forces acting between the drillstring and the wellbore wall. Wellbore mechanical friction attributable to pipe rotation or to torque and drag plays a significant role in drilling operations and is considered to influence the downhole temperatures of the drilling fluid. An analytical model to estimate the influence of this pipe friction will help in providing a better physical insight to understand the downhole borehole conditions as well as in realizing the effect of its underlying parameters. This study aims to develop a simple mathematical model to analyze the heat generated downhole from the drillstring and borehole contact and then predict its influence on the temperature of the drilling fluid during a drilling operation at any depth in the well. The model presents a steady-state solution for heat transfer between the drillstring and the fluids in the drillpipe and annulus, as well as for heat transfer between the annular fluid and the formation. The heat generated from friction has been modeled by use of the torque acting on the drillstring as a result of contact forces. A linear temperature gradient for the formation and a constant borehole-wall temperature has been assumed to simplify the model. Frictional pressure losses in the drillpipe, in the annulus, and across the bit have been incorporated in the model because they contribute to the heat generated downhole. The temperature profile of the drilling fluid has been estimated both in the annulus and inside the drillpipe for the entire well profile under consideration. This paper will present the derivations of the generalized heat-transfer model and its validation by use of two practical drilling scenarios. Two different field cases, one for a deviated well and the other for a horizontal well, have been presented, and the estimated temperature profile by use of the model is compared with the actual temperature measured downhole by use of measurement-while-drilling (MWD) tools. The increase in temperature for a particular depth in the well for the entire bit run has also been presented as another successful application of this model. The impact of drilling parameters on temperatures has also been analyzed and can be used effectively to maintain a better check on undesired temperatures. This simple analytical model can be suitably applied to field cases on the basis of the well profile and can be effectively used to predict the maximal temperatures to be encountered downhole while drilling ahead as planned. An accurate estimation of maximal temperatures will help us prevent severe downhole friction heating in the future.

Wired-Drillpipe Field Trials Reveal Potential Benefits Over Traditional Pipe

This article, written by Editorial Manager Adam Wilson, contains highlights of paper SPE 163560, ’A Summary of Wired-Drillpipe Field Trials and Deployments in BP,’ by Stephen T. Edwards, Chris J. Coley, Nick A. Whitley, Richard G. Keck, SPE, Vishwahnath Ramnath, Tommy Foster, Keith Coghill, and Mark Honey, SPE, BP, prepared for the 2013 SPE/IADC Drilling Conference and Exhibition, Amsterdam, 5-7 March. The paper has not been peer reviewed. Field trials were conducted by BP on the commercial version of wired pipe with a comprehensive suite of logging-while-drilling (LWD) tools, measurement-while-drilling (MWD) functionality, and rotary-steerable- capability on two Wyoming wells in 2007. Since then, BP has deployed wired pipe commercially in more than 14 wells at four additional locations (Trinidad, North Sea, Colombia, and deepwater Gulf of Mexico), representing a good cross section of drilling conditions and challenges. Basics of How Wired Pipe Works Wired drillpipe incorporates a section of coaxial cable in each joint. The cable passes through a gun-drilled hole in the connection on each end of the joint. Between connections, the cable is encased in a strong stainless-steel sheath, which is held in tension within the inner diameter of the pipe adjacent to, but not bonded to, the inner wall. Figs. 1 and 2 show schematics of the wired pipe. Inductive coupling enables the signal to pass from one joint to the next, through ferrous coils that are embedded in the pin end of one joint of pipe and the opposing box end of the subsequent joint of pipe. These coils come very close to each other when the connection is made up, but, because the coupling is inductive, they do not need to touch, and insulating material such as pipe dope does not block the signal. However, over many joints of pipe, there is a loss of signal strength, and, for this reason, a battery-powered booster sub is deployed approximately every 1,500 ft. The booster assemblies also provide housing and a connection point for along-string measurements. On the bottomhole-assembly (BHA) end of the drillstring, wired pipe connects to the measurements providers and steering assembly through an interface sub, enabling two-way communication to the network, usually provided by the LWD provider. At the top of the drillstring, the network is connected to surface servers by a data swivel housed in the top drive. Wired-Pipe-Enabled Applications Real-Time Imaging. Several different LWD imaging tools are commercially available today. Two types of tools that have been run with wired pipe are the LWD azimuthal density imaging tool and LWD resistivity imaging.

Electromagnetic measurement while drilling technology based on the carrier communication principle

Abstract To improve data transfer rate and signal telemetry depth in electromagnetic measurement while drilling (EM-MWD), and to solve the problems of short life expectancy and poor reliability of drill pipes as well as serious electromagnetic scattering, this paper presents the measurement while drilling (MWD) method based on the carrier communication principle. Based on carrier technology, the electromagnetic wave signal was coupled with the drill pipe through the coupling transformer, where the drill pipe and formation can form the guiding wave system to achieve data transfer between the ground and the bottom. The transmission line equation is developed based on the analysis of the transmission characteristics of electromagnetic waves in strata and drill pipes, and the overall structure of the system is presented. The real transmitter and receiver are produced by using LM1893 as the carrier module. In addition, the system optimization is proposed. The electromagnetic waves loaded on the drill pipe using carrier technology can transmit drilling measurement parameters from the bottom to the surface in real time, and send setting parameters and commands from the surface to the bottom simultaneously through the drill pipe-formation channel, and thus achieve the implementation of bi-directional communication between the ground and the bottom.