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.

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.

Performance evaluation of laponite as a mud-making material for drilling fluids

In this study, laponite was tested as a mud-making material for drilling fluids. Laponite is a synthetic smectite clay with a structure and composition closely resembling the natural clay mineral hectorite. Commercially available laponite was characterized by X-ray di ractometry, scanning electron microscopy and infrared spectrometry. Its dispersibility, salt resistance and high-temperature resistance were evaluated. The results showed that laponite possessed superior cation exchange capacity(140.4 mmol/100 g) with interlayer cations of Na^+ and Li^+. Laponite could easily be dispersed in water to yield increased viscosity with no influence from hydration time or temperature. On the other hand, laponite dispersions displayed an excellent heat resistance, with invariant apparent viscosity at high temperatures. For instance, the apparent viscosity of the2 wt% laponite dispersion underwent changes between 22 and 24 mPa s after hot rolling at 180–240 °C for 16 h. Compared to existing mud-making materials, laponite exhibited better mud-making properties. Furthermore, laponite revealed good compatibility with other additives, and the water-based drilling fluids prepared with laponite as mud-making material showed an excellent stability at elevated temperatures and superior performance–cost ratios. Overall, these findings indicated that laponite had an excellent dispersibility at high temperatures and hence would have promising applications as high-temperature mud-making material for preparing water-based drilling fluids designed for ultra-high-temperature environments.

First Identification of ～2.65 Ga Tonalite in the Jiefangyingzi Area,Inner Mongolia

Objective The northern margin of the North China Craton (NCC),as an adjacent part between the northern NCC and the southeastern Central Asian Orogenic Belt (CAOB), has recorded multi-stage tectonic evolution information.

New Geochronologic Evidence of Diabases and Their Metallogenic Relationship with the Makeng-Type Iron Deposits in Southwest Fujian, SE China

Objective The Makeng-type iron deposits are located in Late Paleozoic depression of southwest Fujian Province in the southeast edge of Cathaysia, which are famous for their huge scale and specific ore genesis. Previous studies mainly focus on the ore characteristics, metallogenic setting and the granites in the mining area, and there is still controversy on the ore genesis. Recent research has revealed that the iron ore bodies are spatially closely related to diabase rocks, especially those in the Makeng Fe deposit. Diabase dykes are widely distributed in the Makeng, Luoyang, Zhangkeng and other iron deposits,

The Age of the Original Silurian Badangshan Formation and its Ductile Deformation in the Northern Margin of North China Craton: New Evidence from Zircon SHRIMP U-Pb Ages

Objective Many previous researches have documented the tectonic evolution of the northern margin of North China Craton. However, whether the age of original Silurian Badangshan Formation in the study area belongs to the Archean, Silurian or Devonian remains controversial, and the ductile deformation time of this formation also lack of chronological study. This work focused on the composition of the rocks in the original Silurian Badangshan Formation of the Jiefangyingzi and Dachaoyanggou area of Chifeng, and the U-Pb dating of rhyolite and late intrusive rocks, and then discussed the age of ductile deformation in order to provide new basic information for the structural evolution of this area.

Development and application of turbodrills in hot dry rock drilling

The strata of hot dry rock(HDR) are usually igneous rocks with high temperature which are challenging for drilling activities. This paper deals with the key technology and research of turbodrills, introduced the application of turbodrills in HDR drilling at home and broad, and analyzed the field application cases. With the advancement such as low speed high torque turbodrill, reduction turbodrills, independent spindlesection and PDC bearings and so on, the application of turbodrills has widely expanded. The application of high-temperature turbodrills in Fenton Hill, HDR geothermal wells, high-temperature formation in Tahe oilfield all proved that turbodrills are the best downhole motors in deep high-temperature HDR drilling, thus they deserve further research and generalization.

Thermal stresses analysis of casing string used in enhanced geothermal systems wells

In the enhanced geothermal systems wells, casing temperature variation produces casing thermal stresses, resulting in casing uplift or bucking. When the induced thermal stresses exceed casing material's yield strength, the casing deforms and collapses. The traditional casing design standard only considers the influence of temperature variation on casing material's yield strength. Actually, for commonly used grades of steel pipe, casing's material properties-such as yield strength, coefficient of thermal expansion, and modulus of elasticity change with temperature variation. In this paper, the modified thermal stress equation is given. Examples show that the allowable temperature of the material grade N80's casing is only 164 ℃, which is much lower than that of the traditional design standard. The effective method to improve the casing pipe's allowable temperature is pre-stressed cementing technology. Pre-stressed cementing includes pre-tension stress cementing and pre-pressure stress cementing. This paper focuses on the design method of full casing pre-tension stress cementing and the ground anchor full casing string pre-tension cementing construction process.

Advances in Drilling Instead of Trenching Technology

Traditional surface exposure methods,such as trenching and exploratory shaft sinking,have their own limitations and do harm to the environment.Thus,shallow drilling was applied in geological mapping to expose shallow orebody and to determine the thickness of top soil layer,and then to illustrate bedrock lithology and geological boundary.It can also help to study geological structures and to reveal the orebody shape,and further to combine with rock core sampling and chemical analysis to develop the systematic method of drilling instead of trenching technology.

Lower activity time constraint on the ore-controlling Erdaogou fault in the Qingchengzi orefield of the Liaodong Peninsula,NE China

The Erdaogou fault,also known as the 101 fault,comprises the most important NE strike component in the ore-controlling system in the Qingchengzi orefield,Liaodong Peninsula.Due to the poor outcrop conditions in the field,the Erdaogou fault lacks activity time constraint.We demonstrate the constraint activity time of the fault since we observe a lamprophyre that was cut through by the Erdaogou fault in the Taoyuan area,central to the Qingchengzi orefield.Zircon grains from the lamprophyre dyke exhibit typical oscillatory zoning and yield weighted mean U–Pb age of 223.8±1.1 Ma(MSWD=1.5).The lower activity time limit of the Erdaogou fault is thus first constrained as 224 Ma or so and is correlated with the crystallization age of the Xinling and Shuangdinggou plutons within the orefield.Taking previous mineralization studies into consideration,a Triassic tectonic-magmatism-mineralization model is approved in the Qingchengzi orefield.

Late Paleozoic to Mesozoic extension in southwestern Fujian Province, South China： Geochemical, geochronological and Hf isotopic constraints from basic-intermediate dykes

The tectonic evolution of SE China block since late Paleozoic remains debated. Here we present a new set of zircon U-Pb geochronological, Lu-Hf isotopic data and whole-rock geochemistry for two stages of basicintermediate dykes from the southwestern Fujian. The samples were collected from the NE-trending （mainly diabases） and NW-trending （mainly diabasic diorites） dykes and yielded zircon U-Pb ages of 315 and 141 Ma, with eHf（t） values of -8.90 to 7.49 and -23.39 to -7.15 （corresponding to TDM2 values of 850 to 1890 Ma and 737 to 2670 Ma）, respectively. Geochemically these rocks are characterized by low TiO2 （0.91-1.73 wt.%） and MgO （3.04-7.96 wt.%）, and high A1203 （12.5-16.60 wt.%） and K20 （0.60-3.63 wt.%）. Further they are enriched in LREEs and LILEs （Rb, Ba, Th and K）, but depleted in HFSEs （Nb, Ta and Zr）. The tectonic discrimination analysis revealed that the dykes were formed in an intraplate extensional envi- ronment. However, the NW trending dykes show crust-mantle mixed composition, which indicate an extensional tectonic setting with evidence for crustal contamination. The SE China block experienced two main stages of extensional tectonics from late Carboniferous to early Cretaceous. The tectonic evolution of the SE China block from late Devonian to Cretaceous is also evaluated.

Late Mesozoic Tectonic Evolution of Southwestern Fujian Province,South China:Constraints from Magnetic Fabric,Zircon U-Pb Geochronology and Structural Deformation

A combined study of magnetic fabrics, zircon U-Pb geochronology and structural deformation was carried out for Late Paleozoic sedimentary and Mesozoic magmatic rocks in the southwestern Fujian rift basin, South China, aiming at deciphering the tectonic evolution during Late Mesozoic. Field observations showed that the Late Mesozoic structure deformations in southwestern Fujian were categorized into four phases： NW-SE compression, ENE-WSW extension, NNE-SSW compression and NNW-SSE extension, se- quentially. Zircons picked out from Juzhou granite and WNW-trending diabase dykes showed complete crys- tal shapes and clear oscillatory zonings on their edges, and the U-Pb dating yielded ages of 132 and 141 Ma, respectively. The susceptibility ellipsoid magnitude parameters of the Juzhou granite are characterized by flaser type strain ellipsoid, with pole density center of K3 falling into the first and the third quadrants, these fea- tures revealed that the Juzhou granite formed in ENE-WSW compressional stress field, indicating the early stage of Early Cretaceous extrusion in southwestern Fujian. The late stage of Early Cretaceous NNE-SSW ex- tension was limited by the widespread WNW-trending diabase dykes, which were usually regarded as impor- tant indications for a regional extensional setting. On the basic of the previous researches, structural deforma- tion studies, and the deductions above, it can be concluded that southwestern Fujian experienced five main tectonic stages during Late Mesozoic： Early Jurassic extension, Middie-Late Jurassic thrusting, early stage of Early Cretaceous extension, late stage of Early Cretaceous compression and Late Cretaceous extension.

Preparation of an environmentally friendly emulsion-type lubricant based on crude rice bran wax

In this study,crude rice bran wax oil-in-water emulsion(named CRBWE)was prepared by agent-in-water method.The critical factors influencing the sample preparation process were optimized.For instance,the optimum hydrophile-lipophile balance value of compound emulsifier was 12.33–13.40,the content of compound emulsifier was 10 wt%,the emulsification temperature was 70°C–80°C,the agitation speed was 200 rpm,and the emulsification time was 30–45 min.The performances as a lubricant of drilling fluid were also evaluated with respect to lubricity,rheology and filtration loss of CRBWE.The results showed that CRBWE had good lubricity and didn't affect the rheological properties of drilling fluid.For example,when it was added into bentonite dispersion at room temperature with the fraction of 1 wt%,the coefficient of friction of bentonite dispersion dramatically decreased to 0.077,and the coefficient of friction reduced rate was greater than 80%.Overall,these findings indicated that CRBWE would have promising applications as environmental friendly lubricant of drilling fluids to reduce torque and drag in petroleum and natural gas drilling.

Preparation of fluidized catalytic cracking slurry oil-in-water emulsion as anti-collapse agent for drilling fluids

Fluidized catalytic cracking slurry oil-in-water emulsion(FCCSE)was prepared by using interfacial complexes generation method that was simple and versatile.The critical factors influencing the sample preparation process were optimized,for instance,the optimum value of the mixed hydrophile-lipophile balance of compound emulsifier was 11.36,the content of compound emulsifier was 4 wt%,the emulsification temperature was 75
C,the agitation speed was 200 rpm,and the emulsification time was 30e45 min.The performance as a drilling fluid additive was also investigated with respect to rheological properties,filtration loss and inhibition of FCCSE.Experimental results showed that FCCSE was favorable to inhibiting clay expansion and dispersion and reducing fluid loss.Furthermore,it had good compatibility with other additives and did not affect the rheological properties of drilling fluids.FCCSE exhibited better performance than the available emulsified asphalt.It has a promising application as anti-collapse agent in petroleum and natural gas drilling.

Development and application of guar gum crosslinked gel with adjustable gelation time for total loss treatment

To remediate the problem of severe or total losses,and meet the requirements of borehole plugging and pumping at different well depths,a novel crosslinked polymer gel(named HPG/Zr gel)with controlled gelation time and high gel strength was developed as loss circulation material,which mainly comprised hydroxypropyl guar gum,zirconium compound and triethanolamine.The influence of hydroxypropyl guar gum concentration,zirconium compound concentration,triethanolamine concentration and temperature on the gelation time of HPG/Zr gel was evaluated.In addition,the performance of HPG/Zr gel was investigated in terms of temperature resistance and shear resistance property,plugging ability and supporting cement slurry ability.According to the results,HPG/Zr gel can form a viscoelastic body with a network structure,and its gelation time can be practically adjustable.The results of the plugging experiment at different temperatures,pressures and pore sizes of quartz sand revealed that HPG/Zr gel could effectively plug sand pores at 150℃,and its pressure-bearing capacity can be up to 5 MPa.Employing its flow resistance and ability of supporting cement slurry,HPG/Zr gel was successfully applied in two geological boreholes by combining with cement slurry.Overall,the results of laboratory research and field tests indicate that HPG/Zr gel is useful for mitigating the lost circulation,and it is of huge importance to engineering applications.

Research on slim-hole drilling technology for shale gas geological survey in China

Over the last 10 years,the China Geological Survey has deployed 137 slim-hole shale gas geological exploration wells for coring entire wellbores.These wells are primarily located in new blocks and geological formations where neighboring well data are insufficient,beyond the scope of developed oil fields in China,or outside of oil and gas company mining-right areas.The drilling rig equipment,coring tools,and core drill bits of slim-hole shale gas drilling technology are different from those associated with traditional petroleum drilling.Many studies have been conducted on non-coring slim-hole drilling technology.This paper focuses on coring technology and drilling safety,summarizing a set of high-efficiency shale gas drilling equipment and technology systems based on geological drilling equipment and techniques(that can be used for solid mineral exploration).We report on:1)an improved vertical shaft drilling rig adapted to shale gas well control safety;2)high-efficiency core drilling techniques,focusing on coring tools,and techniques incorporating an inverted tower drilling tool combination,air circulation follow-through technology,and expanded casing technology;3)research progress on high-efficiency core drill bits,including non-planar tooth polycrystalline diamond compact bits and impregnated diamond core bits,along with their application effects.This research provides substantial advances in drill-core technology and improvements in exploration efficiency.Moreover,it provides a reference frame for well structural design and selection of construction technology for shale gas exploration drilling projects.