Research into magnetic guidance technology for directional drilling in SAGD horizontal wells

SAGD horizontal wells are used to enhance oil recovery from heavy oil reservoirs.This technology requires precise separation between the production well and the injection well to ensure the efficient drainage of the reservoir.By studying the attitude of the downhole probe tube and the production well trajectory,an algorithm is proposed for eliminating ferromagnetic interference while drilling injection wells.A high accuracy filter circuit has been designed to correct the detected magnetic signals,which are ultra-weak,frequency-instable,and narrow-band.The directional drilling magnetic guidance system（DD-MGS） has been developed by integrating these advanced techniques.It contains a sub-system for the ranging calculation software,a magnetic source,a downhole probe tube and a sub-system for collecting ＆ processing the detected signals.The DD-MGS has succeeded in oilfield applications.It can guide the directional drilling trajectory not only in the horizontal section but also in the build section of horizontal injection wells.This new technology has broad potential applications.

Application and development of numerical simulation for under- ground horizontal directional drilling

In coalmines of China, horizontal directional drilling （HDD） is an increasingly popular method for underground in-seam gas drainage. Numerical simulation, especially finite element analysis, is often used as an effective method to improve HDD operation. These improvements focus on rock-breaking efficiency, directional precision, stability of the borehole wall, and reliability of the drill equipment. On the basis of underground drilling characteristics, typical numerical simulation exam- ples in drilling techniques and equipment are summarized and analyzed. In the end, the future development trends of numerical simulation in underground in-seam drilling are proposed.

Research on Horizontal Vibration of Heavy-Weight Drill Pipes in Directional Drilling

The mode of load and deformation of directional drilling string and the expression of trigonometric series of deflection equation are established by means of elastic deformation energy and of the vertical and horizontal bending. A calculation formula for natural frequency of horizontal resonance and rotational speed is derived based on the calculation method by Ritz, with which analysis is made for the cause and affecting factors of the excessive abrasion of heavy-weight drill pipe in high-angle holes so as to provide reference and basis for rational selection of drilling parameters and drilling tools in the future high-angle directional drilling.

Two stages power generation test of the hot dry rock exploration and production demonstration project in the Gonghe Basin,northeastern Qinghai-Tibet plateau,China

The Hot Dry Rock(HDR)is considered as a clean and renewable energy,poised to significantly contribute to the global energy decarbonization agenda.Many HDR projects worldwide have accumulated valuable experience in efficient drilling and completion,reservoir construction,and fracture simulation.In 2019,China Geological Survey(CGS)initiated a demonstration project of HDR exploration and production in the Gonghe Basin,aiming to overcome the setbacks faced by HDR projects.Over the ensuing four years,the Gonghe HDR project achieved the first power generation in 2021,followed by the second power generation test in 2022.After establishing the primary well group in the initial phase,two directional wells and one branch well were drilled.Noteworthy progress was made in successfully constructing the targeted reservoir,realizing inter-well connectivity,power generation and grid connection,implementing of the real-time micro-seismic monitoring.A closed-loop technical validation of the HDR exploration and production was completed.However,many technical challenges remain in the process of HDR industrialization,such as reservoir fracture network characterization,efficient drilling and completion,multiple fracturing treatment,continuous injection and production,as well as mitigation of induced seismicity and numerical simulation technology.

Evolution and application of in-seam drilling for gas drainage

The presence of seam gas in the form of methane or carbon dioxide presents a hazard to underground coal mining operations.In-seam drilling has been undertaken for the past three decades for gas drainage to reduce the risk of gas outburst and lower the concentrations of seam gas in the underground ventilation.The drilling practices have reflected the standards of the times and have evolved with the development of technology and equipment and the needs to provide a safe mining environment underground.Early practice was to adapt equipment from other felds,with rotary drilling being the only form of drilling available.This form of drainage allowed various levels of gas drainage coverage but with changing emphasis,research and development within the coal industry has created specifc equipment,technology and practices to accurately place in-seam boreholes to provide effcient and effective gas drainage.Research into gas content determination established a standard for the process and safe levels for mining operations to continue.Surveying technology improved from the wire-line,single-shot Eastman survey instruments which was time-dependent on borehole depth to electronic instruments located in the drill string which transmitted accurate survey data to the drilling crew without time delays.This allowed improved directional control and increased drilling rates.Directional drilling technology has now been established as the industry standard to provide effective gas drainage drilling.Exploration was identifed as an additional beneft with directional drilling as it has the ability to provide exploration data from long boreholes.The ability of the technology to provide safe and reliable means to investigate the need for inrush protection and water drainage ahead of mining has been established.Directional drilling technology has now been introduced to the Chinese coal industry for gas drainage through a practice of auditing,design,supply,training and ongoing support.Experienced drilling crews can offer site specifc gas drainage drilling services utilising the latest equipment and technology.

Analysis on Well Drilling Example of Deepwater Block in the Gulf of Mexico

With the innovation and development of offshore oil drilling technology, drilling wells in deep waters areas have become an important activity for the development of new hydrocarbon reservoirs in this type of environment. CNOOC (China National Offshore Oil Corporation) won the rights to exploit two unexplored deepwater blocks in the Gulf of Mexico, in a bid realized by the Mexican Government (CNH), in 2016. The challenge to combine the newest technology with the oil industry experienced knowledge to lead the exploration and development of these deep-water blocks in Mexico is around the corner. Therefore, the basic techniques for deep waters wells drilling and the main potential risks are expounded in this paper. A set of deep waters wells drilling processes and methodologies are previously designed, and a specific case is demonstrated next, which provides a referential model for deep waters wells drilling in the Gulf of Mexico.

Surface settlement induced by horizontal directional drilling

Horizontal directional drilling(HDD)is a widely used trenchless method for underground utility connections.The associated ground settlement triggered by HDD depends on the size,types,and surface texture of pipe,diameter of borehole,and soil conditions.The pre-sent study investigates the surface settlement due to the construction of a 1067 mm diameter HDD,which will replace an existing sewer siphon under the SR-60 highway in Chino,California using empirical,and numerical methods.Based on the results obtained from the subsurface investigation,an empirical analysis was conducted first.followed by numerical modeling of the HDD using PLAXIS 2D soft-ware.A careful comparison between two different methods indicated closer values of surface settlement between the empirical method(7.3 mm)and the numerical modeling(4.6 mm).In addition,the shape of surface settlement and horizontal settlement curves for the empirical and numerical methods was found to be similar.The minor discrepancy between the two methods resulted as the numerical model can host several soil layers whereas the empirical equation can use only one type of soil.Finally,a parametric study was conducted to evaluate the effect of borehole cover depth,size,and soil parameters on surface settlement.It was observed that soil strength param-eters yielded a greater effect on surface movement,whereas modulus of elasticity has a relatively smaller influence with zero contribution from Poisson’s ratio.

The first power generation test of hot dry rock resources exploration and production demonstration project in the Gonghe Basin,Qinghai Province,China

Hot dry rock(HDR)is a kind of clean energy with significant potential.Since the 1970s,the United States,Japan,France,Australia,and other countries have attempted to conduct several HDR development research projects to extract thermal energy by breaking through key technologies.However,up to now,the development of HDR is still in the research,development,and demonstration stage.An HDR exploration borehole(with 236℃ at a depth of 3705 m)was drilled into Triassic granite in the Gonghe Basin in northwest China in 2017.Subsequently,China Geological Survey(CGS)launched the HDR resources exploration and production demonstration project in 2019.After three years of efforts,a sequence of significant technological breakthroughs have been made,including the genetic model of deep heat sources,directional drilling and well completion in high-temperature hard rock,large-scale reservoir stimulation,reservoir characterization,and productivity evaluation,reservoir connectivity and flow circulation,efficient thermoelectric conversion,monitoring,and geological risk assessment,etc.Then the whole-process technological system for HDR exploration and production has been preliminarily established accordingly.The first power generation test was completed in November 2021.The results of this project will provide scientific support for HDR development and utilization in the future.

Experimental Study of Rock Drill-ability Anisotropy by Acoustic Velocity

Rock drill-ability anisotropy has significant effects on directional drilling and deviation control. Its evaluation is an important but difficult research subject. Definitions of drill-ability anisotropy and acoustic anisotropy of rock are given in this paper. The acoustic velocities and the drill-ability parameters of several rock samples from the Engineering Center for Chinese Continemal Scientific Drilling （CCSD） are respectively measured with the device for testing the rock drill-ability and the ultrasonic testing system in laboratory, so that their drill-ability anisotropy and acoustic anisotropy are respectively calculated and discussed in detail by using the experimental data. On the basis of these experimental results and calculations, correlations between drill-ability anisotropy and acoustic anisotropy of the rock samples are illustrated through regression analyses. Thus, a mathematical model developed may be used to evaluate the rock drill- ability anisotropy with the acoustic logging or seismic data to a certain extent.

Comparison of accuracy and computational performance between the machine learning algorithms for rate of penetration in directional drilling well

Oil and gas reservoirs are of the main assets of countries possessing them.Production from these reservoirs is one of the main concerns of engineers,which can be achieved by drilling oil and gas reservoirs.Construction of hydrocarbon wells is one of the most expensive operations in the oil industry.One of the most important parameters affecting drilling cost is the rate of penetration(ROP).This paper predicts the rate of penetration using artificial intelligence and hybrid models on Kaboud oil field well#7 in the directional stage.In this study,different models were constructed through various approaches based on 1878 dataset obtained from drilling operation in the well#7.Then,the accuracy of the constructed models was compared with each other.It was found that the MLP-ABC algorithm predicts the rate of penetration more accurately,by far,as compared with other methods.The MLP-ABC algorithm achieves impressive ROP prediction accuracy(RMSE=0.007211 m/h;AAPD=0.1871%;R^(2)=1.000 for the testing subset).Consequently,it can be concluded that this method is applicable to predict the drilling rate in that oilfield.

Laboratory study of fluid properties owing to cutting intrusions during horizontal directional drilling

During horizontal directional drilling installations,a primary function of drilling fluids is to yield drill cuttings and lubricate the product pipe.This paper presents the results of a research study of drilling fluid parameters,and the filter cake properties associated with drill cutting intrusions.Different sand meshes and field cutting sizes were added to the drilling fluids.Based on the laboratory experiments of eighteen samples including testing drilling fluid rheology and filter cake properties,the influence of drill cuttings on low solid-phase drilling fluid systems were obtained.The results reveal that drilling fluid plastic viscosity values increase with sand content and particle size.The 100-mesh sand exhibits a larger plastic viscosity compared to the 200-mesh sand.This suggests that the coarser the sand,the greater is the plastic viscosity.By contrast,drilling fluids with 200-mesh sand exhibit greater shear forces than the 100-mesh sand.When the sand content is4%,the shear dilution ability of the drilling fluid begins to weaken.The thinnest filter cake is formed after 6 h with a 100-mesh cutting size and 4%sand content.However,when the cutting size changed to 150-mesh and 2%content,the largest filter cake toughness and strength after rolling for 12 h were obtained.Simultaneously,the combination of 200-mesh and 150-mesh with 2%–4%content rolling for 12–24 h indicate different results.For the filter cake thickness,cutting content is the primary influencing factor followed by particle size and gradation.The factor with the least influence is rolling time.We found that rolling time and gradation were the most significant factors affecting the toughness of the filter cake,followed by cutting content.Conversely,particle size exhibits the least influence on filter cake toughness.These results are important to better understand the solid-phase control of drilling fluids in the field.

BIM for the Underground-An enabler of trenchless construction

The subsurface space in urban areas is an important asset.However,the information available on this environment is relatively poor compared to above ground information.This paper proposes a Building Information Model(BIM)for underground applications as means to address this information gap.The creation and progressive update of BIM for a constructed artefact ensures that data on the structures is available and can be used throughout its lifetime.A BIM for underground applications integrates data on surface structures,such as buildings,and subsurface infrastructures,such as pipes,along with details of the surrounding ground,the associated soil and rock properties and groundwater regime into a single framework.This approach is demonstrated by applying it to trenchless construction operations,including a microtunnelling project for a new sewer.The data from this extended BIM concept can be interactively used with analysis packages to conduct risk assessments for new construction activities.It also shows how BIM for the Underground can be used throughout the planning,construction and post-construction stages of a project,and,importantly,how this information can be available for future projects.