Pre-Drilling Prediction Techniques on the High-Temperature High-Pressure Hydrocarbon Reservoirs Offshore Hainan Island,China

Decreasing the risks and geohazards associated with drilling engineering in high-temperature high-pressure(HTHP) geologic settings begins with the implementation of pre-drilling prediction techniques(PPTs). To improve the accuracy of geopressure prediction in HTHP hydrocarbon reservoirs offshore Hainan Island, we made a comprehensive summary of current PPTs to identify existing problems and challenges by analyzing the global distribution of HTHP hydrocarbon reservoirs, the research status of PPTs, and the geologic setting and its HTHP formation mechanism. Our research results indicate that the HTHP formation mechanism in the study area is caused by multiple factors, including rapid loading, diapir intrusions, hydrocarbon generation, and the thermal expansion of pore fluids. Due to this multi-factor interaction, a cloud of HTHP hydrocarbon reservoirs has developed in the Ying-Qiong Basin, but only traditional PPTs have been implemented, based on the assumption of conditions that do not conform to the actual geologic environment, e.g., Bellotti's law and Eaton's law. In this paper, we focus on these issues, identify some challenges and solutions, and call for further PPT research to address the drawbacks of previous works and meet the challenges associated with the deepwater technology gap. In this way, we hope to contribute to the improved accuracy of geopressure prediction prior to drilling and provide support for future HTHP drilling offshore Hainan Island.

A Study of High-Temperature and High-Pressure Experiment of Correlativity between Deformational System of Au-Bearing Rocks and Element Adjustment

Modelling of migration and accumulation of elements Au and Ag in rocks under temperatures of 350–450°C and a confining pressure of 300 MPa and axial pressure of 100–150 MPa is conducted. It is found that the contents of gold and silver get higher in metallic sulphides such as pyrite, chalcopyrite and sphalerite as well as in quartz and muscovite, and get lower in chlorite, biotite, seriate, albite and calcite, showing that tectono-dynamics is one of the important factors for petrogenesis and metallogenesis.

Reaction mechanism of metal and pyrite under high-pressure and high-temperature conditions and improvement of the properties

Pyrite tailings are the main cause of acid mine wastewater.We propose an idea to more effectively use pyrite,and it is modified by exploiting the reducibility of metal represented by Al under high-pressure and high-temperature(HPHT)conditions.Upon increasing the Al addition,the conductivity of pyrite is effectively improved,which is nearly 734 times higher than that of unmodified pyrite at room temperature.First-principles calculations are used to determine the influence of a high pressure on the pyrite lattice.The high pressure increases the thermal stability of pyrite,reduces pyrite to highconductivity Fe7S8(pyrrhotite)by Al.Through hardness and density tests the influence of Al addition on the hardness and toughness of samples is explored.Finally we discuss the possibility of using other metal-reducing agents to improve the properties of pyrite.

High-pressure Raman study of MgV_2O_6synthesized at highpressure and high temperature

A new structural phase of MgV2O6 was obtained by a high-pressure, high-temperature （HPHT） synthesis method. The new phase was investigated by the Rietveld analysis of X-ray powder diffraction data, showing space group Pbcn （No. 60） symmetry and a = 13.6113（6）A （1A =0.1 nm）, b = 5.5809（1）A, c = 4.8566（3）A, V = 368.93（2）A3 （Z = 4）. High pressure behavior was studied by Raman spectroscopy at room temperature. Under 22.5 GPa, there was no sign of a structural phase transition in the spectra, demonstrating stability of the HPHT phase up to the highest pressure.

Structural Stability of Natural Magnesiochromite at High-Temperature-Pressure Conditions

The podiform chromitites in the Luobusha ophiolite have been thought to experience a very deep formation,but the maximum depth is still an open issue.Here,we have investigated the structural stability of natural magnesiochromite using the synchrotron-based powder X-ray diffraction and diamond anvil cells up to 48.6 GPa and 2450 K.The results have shown that spinel-type magnesiochromite first decomposes into corundum-type‘Cr_(2)O_(3)’+B1-type‘MgO’at 11–14 GPa and 1250–1450 K,then modified ludwigite(mLd)-type‘Mg_(2)Cr_(2)O_(5)’+corundum-type‘Cr_(2)O_(3)’at 14.3–20.5 GPa and 1300–2000 K,and finally CaTi_(2)O_(4)-type phase at 24.5 GPa.During the quenching procession from high-temperature-pressure conditions,the mLd-type phase appeared again and was kept at ambient conditions.We also obtained the isothermal equation states of spinel-type and CaTi_(2)O_(4)-type phases,revealing the composition effect on their elasticities.Based on the updated results,we propose chromitites could not experience pressure exceeding∼14.3 GPa(approximate maximum depth∼400 km)in the subduction-recycling genesis model.

Experimental study on reactions between alkaline basaltic melt and orthopyroxenes: constraints on the evolution of lithospheric mantle in the North China Craton

The experimental results of the reactions between an alkaline basaltic melt and mantle orthopyroxenes under high-temperature and high-pressure conditions of 1300–1400℃ and 2.0–3.0 GPa using a six-anvil apparatus are reported in this paper.The reactions are proposed to simulate the interactions between melts from the asthenospheric mantle and the lithospheric mantle.The starting melt in the experiments was made from the alkaline basalt occurring in Fuxin,Liaoning Province,and the orthopyroxenes were separated from the mantle xenoliths in Damaping,Hebei Province.The results show that clinopyroxenes were formed in all the reactions between the alkaline basaltic melt and orthopyroxenes under the studied P–T conditions.The formation of clinopyroxene in the reaction zone is mainly controlled by dissolution–crystallization,and the chemical compositions of the reacted melt are primarily infl uenced by the diff usion eff ect.Temperature is the most important parameter controlling the reactions between the melt and orthopyroxenes,which has a direct impact on the melting of orthopyroxenes and the diff usion of chemical components in the melt.Temperature also directly controls the chemical compositions of the newly formed clinopyroxenes in the reaction zone and the reacted melt.The formation of clinopyroxenes from the reactions between the alkaline basaltic melt and orthopyroxenes can result in an increase of CaO and Al_(2)O_(3) contents in the rocks containing this mineral.Therefore,the reactions between the alkaline basaltic melt from the asthenospheric mantle and orthopyroxenes from the lithospheric mantle can lead to the evolution of lithospheric mantle in the North China Craton from refractory to fertile with relatively high CaO and Al 2 O 3 contents.In addition,the reacted melts in some runs were transformed from the starting alkaline basaltic into tholeiitic after reactions,indicating that tholeiitic magma could be generated from alkaline basaltic one via reactions between the latter and orthopyroxene.

Gold solubility in silicate melts and fluids:Advances from high-pressure and high-temperature experiments

The solubility of Au in silicate melts and fluids governs the enrichment and migration of Au during the formation of magmatic-hydrothermal Au deposits.Large Au deposits require vast amounts of Au to migrate from the upper mantle-lower crust to the shallow crust,and high Au solubility in magma and hydrothermal fluid facilitates the formation of Au-rich magma and fluid in the crust and mantle source and efficient transport.This paper reviews recent high-pressure and high-temperature experimental studies on Au species in magmas and hydrothermal fluids,the partitioning behavior of Au between silicate melts and fluids,and the effects of temperature,pressure,oxygen fugacity,sulfur fugacity,silicate melt composition,and volatiles(H2O,CO2,chlorine,and sulfur)on the solubility of Au in magma.We show that the solubility of Au in magma is largely controlled by the volatiles in the magma:the higher the content of reduced sulfur(S2-and HS-)in the magma,the higher the solubility of Au.Under high-temperature,high-pressure,H2O-rich,and intermediate oxygen fugacity conditions,magma can dissolve more reduced sulfur species,thus enhancing the ability of the magma to transport Au.If the ore-forming elements of the Au deposits in the North China Craton originate from mantle-derived magmas and fluids,we can conclude,in terms of massive Au migration,that these deep Au-rich magmas might have been generated under H2 O-rich and moderately oxidized conditions(S2-coexists with S6+).The big mantle wedge beneath East Asia was metasomatized by melts and fluids from the dehydration of the Early Cretaceous paleo-Pacific stagnant slab,which not only caused thinning of the North China Craton,but also created physicochemical conditions favorable for massive Au migration.

Trace element composition in tuite decomposed from natural apatite in high-pressure and high-temperature experiments

Tuite has been suggested as a potential reservoir for trace elements in the deep mantle,but no evidence confirms this supposition.By using a natural apatite as starting material,the trace-element-bearing tuite large crystals were obtained under highpressure and high-temperature conditions(15 GPa and 1800 K).X-ray diffraction pattern and Micro-Raman spectrum of the run product confirm that tuite was synthesized.The concentrations of trace elements in tuite crystals were analyzed by laser ablation-inductively coupled plasma-mass spectrometry(LA-ICP-MS).The rare earth element patterns of tuite show enrichment of light rare earth elements relative to heavy rare earth elements.Tuite shows high concentrations of Th and Sr,and negative anomalies of Rb,Nb,and Hf.The results show that tuite can accommodate a large amount of trace elements.Tuite might be an important host to accommodate trace elements if there is much apatite subducted into the deep mantle.

Recent advance in hollow-core fiber high-temperature and high-pressure sensing technology [Invited]

The pure-silica hollow-core fiber(HCF) has excellent thermostabilities that can benefit a lot of high-temperature sensing applications.The air-core microstructure of the HCF provides an inherent gas container, which can be a good candidate for gas or gas pressure sensing.This paper reviews our continuous efforts to design, fabricate, and characterize the hightemperature and high-pressure sensors with HCFs, aiming at improving the sensing performances such as dynamic range,sensitivity, and linearity.With the breakthrough advances in novel anti-resonant HCFs, sensing of high temperature and high pressure with HCFs will continuously progress and find increasing applications.

High-temperature High-pressure Hydrothermal Synthesis of Dy3＋-doped YNbO4 Single Crystal and Its Luminescence Properties

Single crystal Dy3＋ doped YNbO4phosphors were prepared via a high-temperature high-pressure hydrothermal procedure. Under excitation at 270 nm, the Dy3＋-doped YNbO4 phosphor shows bright white emission, which is composed of two strong bands at 492 and 576 nm corresponding to the characteristic 4F9/2→6H15/2 and aF9/2→6H13/2 transitions of Dy3＋, respectively. The dominant band was observed at 352 nm, which corresponds to the 6H15/2→6p7/2 transition of Dy3＋. Nearly white light was achieved at 2ex 270, 310 and 388 nm and the CIE（International Commission on Illumination） values were （0.3135, 0.3421）, （0.3088, 0.3380） and （0.3146, 0.3296）, respectively.

Extraordinary high-temperature mechanical properties in binder-free nanopolycrystalline WC ceramic

From the perspective of high-temperature applications,materials with excellent high-temperature mechanical properties are always desirable.The present work demonstrates that the binder-free nanopolycrystalline WC ceramic with an average grain size of 103 nm obtained by high-pressure and hightemperature sintering exhibits excellent mechanical properties at both room temperature and high temperature up to 1000℃.Specifically,the binder-free nanopolycrystalline WC ceramic still maintains a considerably high Vicker hardness H_(V)of 23.4 GPa at 1000℃,which is only 22%lower than the room temperature H_(V).This outstanding thermo-mechanical stability is superior to that of typical technical ceramics,e.g.SiC,Si_(3)N_(4),Al_(2)O_(3),etc.Nanocrystalline grains with many dislocations,numerous low-energy,highly stableΣ2 grain boundaries,and a relatively low thermal expansion coefficient,are responsible for the observed outstanding high-temperature mechanical properties.

High-pressure sound velocity of perovskite-enstatite and the possible composition of the Earth's lower mantle

The compressional sound velocity VP for enstatite of polycrystalline specimens were measured at pressures from 40 to 140 GPa using the optical analytical techniques under shock loading. The dependence of VP (in km/s) on Hugoniot pressure (P, in GPa) can be described by lnVP= 3.079-0.691 ln(P) + 0.094(lnP)2. VP satisfies Birch’s law: VP= 4.068 + 1.677p, where p is corresponding density, which indicated that enstatite is stable throughout the conditions of the lower mantle. The wave velocity P is 0.5% lower and the wave velocity S is 2% higher than that of PREM respectively. We concluded that the lower mantle is mainly composed of perovskite-(Mg1-x, Fex) SiO3 and only a small amount of (Mg1-x, Fex) O is allowed in it.

Effect of Carbon Source with Different Graphitization Degrees on the Synthesis of Diamond

Using three kinds of graphites with different graphitization degrees as carbon source and Fe-Ni alloy powder as catalyst, the synthesis of diamond crystals is performed in a cubic anvil high-pressure and high-temperature apparatus （SPD-6 × 1200）. Diamond crystals with perfect hexoctahedron shape are successfully synthesized at pressure from 5.0 to 5.5GPa and at temperature from 1570 to 1770K. The synthetic conditions, nucleation, morphology, inclusion and granularity of diamond crystals are studied. The temperature and pressure increase with the increase of the graphitization degree of graphite. The quantity of nucleation and granularity ofdiamonds decreases with the increase of graphitization degree of graphite under the same synthesis conditions. Moreover, according to the results of the M6ssbauer spectrum, the composition of inclusions is mainly Fe3 C and Fe-Ni alloy phases in diamond crystals synthesized with three kinds of graphites.

An experimental study of interaction between pure water and alkaline feldspar at high temperatures and pressures

Due to the important scientific significance of the interaction between alkaline feldspar and high-temperature and high-pressure fluids. We have conducted a series of autoclave experiments of feldspar dissolution and secondary mineral precipitation in conditions of 250–500℃, 8-50 MPa, and pH = 3.0 and 5.5. Based on the interaction experiments between alkaline feldspar and fluid of high-temperatures and high-pressures, we get the main results as follows:(1) The law that people have grasped below the critical point about the influence of temperature, pressure, and pH value on the alkaline feldspar dissolution behavior is still held above the critical point.(2) Due to the experimental techniques of autoclave flip 180°—sharp quenching and based on electron microprobe analysis of mineral new formed, theoretical analysis has determined that the new altered minerals distributed on the island dissolution surface of feldspar are products of precipitation on a feldspar surface after saturation of the relative ion concentration in water fluid.

Thermal equation of state of a natural kyanite up to 8.55 GPa and 1273 K

The thermal equation of state of a natural kyanite has been investigated with a DIA-type,cubic-anvil apparatus(SAM85)combined with an energy-dispersive synchrotron X-ray radiation technique up to 8.55 GPa and 1273 K.No phase transition was observed in the studied pressure-temperature(P-T)range.The Le Bail full profile refinement technique was used to derive the unit-cell parameters.By fixing the bulk modulus K 0 as 196 GPa and its pressure derivative K0 as 4,our P-V(volume)-T data were fitted to the high temperature BircheMurnaghan equation of state.The obtained parameters for the kyanite are:V_(0)=294.05(9)Å^(3),a=2.53(11)×10^(-5)K^(-1) and(K/T)P=-0.021(8)GPa∙K^(-1).These parameters have been combined with other experimentally-measured thermodynamic data for the relevant phases to calculate the P-T locus of the reaction kyanite¼stishoviteþcorundum.With this thermodynamically constrained phase boundary,previous high-pressure phase equi-librium experimental studies with the multi-anvil press have been evaluated.

Thermoelasticity and stability of natural epidote at high pressure and high temperature:Implications for water transport during cold slab subduction

Epidote is a typical hydrous mineral in subduction zones.Here,we report a synchrotron-based single-crystal X-ray diffraction(XRD)study of natural epidote[Ca1.97Al2.15Fe0.84(SiO4)(Si2O7)O(OH)]under simultaneously high pressure-temperature(high P-T)conditions to~17.7 GPa and 700 K.No phase transition occurs over this P-T range.Using the third-order Birch-Murnaghan equation of state(EoS),we fitted the pressure-volume-temperature(P-V-T)data and obtained the zero-pressure bulk modulus K_(0)=138(2)GPa,its pressure derivative K'_(0)=3.0(3),the temperature derivative of the bulk modulus((∂K/∂T)P=-0.004(1)GPa/K),and the thermal expansion coefficient at 300 K(α_(0)=3.8(5)×10^(-5)K^(-1)),as the zero-pressure unit-cell volume V_(0)was fixed at 465.2(2)Å^(3)(obtained by a single-crystal XRD experiment at ambient conditions).This study reveals that the bulk moduli of epidote show nonlinear compositional dependence.By discussing the stabilization of epidote and comparing its density with those of other hydrous minerals,we find that epidote,as a significant water transporter in subduction zones,may maintain a metastable state to~14 GPa along the coldest subducting slab geotherm and promote slab subduction into the upper mantle while favoring slab stagnation above the 410 km discontinuity.Furthermore,the water released from epidote near 410 km may potentially affect the properties of the 410 km seismic discontinuity.

Critical behavior and effect of Sr substitution in double perovskite Ca2CrSbO6

The double perovskite Ca2CrSbO6 exhibits a ferromagnetic long-range order below Tc=13 K and a saturation magnetization of 2.35µB at 2 K.In this study,the polycrystalline Ca2CrSbO6 is synthesized under high pressure and high temperature,and the critical behavior of the ferromagnetic material as well as the effects of the magnetic behavior due to the isovalent substitution of Sr2+for Ca2+is investigated.Also studied are the ferromagnetic criticality of the double perovskite Ca2CrSbO6 at the ferromagnetic transition temperature Tc≈12.6 K from the isotherms of magnetization M(H)via an iteration process and the Kouvel–Fisher method.The critical exponents associated with the transition are determined as follows:β=0.322,γ=1.241,andδ=4.84.The magnetization data in the vicinity of Tc can be scaled into two universal curves in the plot of M/|ε|βversus H/|ε|β+γ,whereε=T/Tc−1.The obtainedβandγvalues are consistent with the predicted values from a three-dimensional Ising model.The effects of Sr substitution on the double perovskite Ca2CrSbO6 are taken into consideration.As the Sr content increases,the(Ca2−xSrx)CrSbO6 polycrystal shows a continuous switch from ferromagnetic to antiferromagnetic behavior.

Geochemical models of core-mantle differentiation

The core-mantle differentiation process is one of the most significant events in the Earth’s early history,which profoundly affects the Earth’s internal structure.According to the simple core-mantle differentiation mechanism,elements such as iron and nickel should be extracted from silicate to form an iron-rich proto-core,and the residual silicate materials form the proto-mantle.However,the composition of the lower mantle and the core remains controversial,which largely affects the partition of elements,thus the referred differentiation process of the Earth.In recent years,many experimental studies on the partition coefficient of siderophile elements between metal and silicate under high-temperature and high-pressure conditions have put forward new ideas on the issues around Earth’s core-mantle differentiation.Meanwhile,some researchers suggested that the redox state of the Earth’s mantle changes during its formation and evolution,and many isotope geochemistry studies support that some enstatite chondrites have a common nebular precursor as the Earth.These new studies bring dispute on the Earth’s building materials,which dominates the core-mantle differentiation process and largely affects the partitioning behaviors of elements during the core-mantle differentiation.This chapter aims to review recent experimental studies on the siderophile element geochemistry and discussions on the Earth’s building blocks.

Research on thermal insulation materials properties under HTHP conditions for deep oil and gas reservoir rock ITP-Coring

Deep oil and gas reservoirs are under high-temperature conditions,but traditional coring methods do not consider temperature-preserved measures and ignore the influence of temperature on rock porosity and permeability,resulting in distorted resource assessments.The development of in situ temperaturepreserved coring(ITP-Coring)technology for deep reservoir rock is urgent,and thermal insulation materials are key.Therefore,hollow glass microsphere/epoxy resin thermal insulation materials(HGM/EP materials)were proposed as thermal insulation materials.The materials properties under coupled hightemperature and high-pressure(HTHP)conditions were tested.The results indicated that high pressures led to HGM destruction and that the materials water absorption significantly increased;additionally,increasing temperature accelerated the process.High temperatures directly caused the thermal conductivity of the materials to increase;additionally,the thermal conduction and convection of water caused by high pressures led to an exponential increase in the thermal conductivity.High temperatures weakened the matrix,and high pressures destroyed the HGM,which resulted in a decrease in the tensile mechanical properties of the materials.The materials entered the high elastic state at 150℃,and the mechanical properties were weakened more obviously,while the pressure led to a significant effect when the water absorption was above 10%.Meanwhile,the tensile strength/strain were 13.62 MPa/1.3%and 6.09 MPa/0.86%at 100℃ and 100 MPa,respectively,which meet the application requirements of the self-designed coring device.Finally,K46-f40 and K46-f50 HGM/EP materials were proven to be suitable for ITP-Coring under coupled conditions below 100℃ and 100 MPa.To further improve the materials properties,the interface layer and EP matrix should be optimized.The results can provide references for the optimization and engineering application of materials and thus technical support for deep oil and gas resource development.

Evaluation of the viability of nanoparticles in drilling fluids as additive for fluid loss and wellbore stability

Wellbore instability is an issue that,if left untreated,can cause wells to collapse,resulting in human,environmental,equipment,and revenue losses.Drilling fluids have been used to enhance the drilling process by lubricating and cooling the drill bit,eliminating cuttings,and most importantly,by improving the stability of the well by preventing fluid loss.However,there has been an increase in operational demands and challenges that call for drilling fluids to be more effective,economical,sustainable,and environmentally friendly.With shales that have infinitesimally small pores,nanoparticle additives in drilling fluids can be crucial in providing the properties that are necessary to prevent fluid loss and provide wellbore stability while meeting the operational demands of the present day.Therefore,this paper examines the use of nanoparticle additives including copper(Ⅱ)oxide(CuO),magnesium oxide(MgO),and aluminum oxide(Al_(2)O_(3))where they are tested under three conditions using the permeable plugging tester(PPT),high-temperature high-pressure(HTHP)fluid loss apparatus,and API low-temperature e low-pressure(LTLP)fluid loss apparatus under concentrations of 0.03%and 0.10%.Finally,based on the results,each nanoparticle sample(particle sizes between one and 100 nm)performed well in contributing to the aim of this project.CuO is the most effective inhibitor across all concentrations and under the three different conditions.It contributed to reducing the fluid loss from 37.6 mL to 18.2 and 13.2 mL,which is between 52%and 65%of fluid reduction.For MgO,it contributed to fluid loss reduction to 23.8 mL and 15 mL,which translated to 37%e60%of fluid loss reduction.The use of Al_(2)O_(3) nanoparticles resulted in a fluid loss reduction to 33.6 mL and 17.8 mL,reducing the fluid loss up to 11%,at HTHP and up to 53%at LTLP.Unlike CuO and MgO,Al_(2)O_(3) was less effective under HTHP conditions when compared to LTLP conditions.Al_(2)O_(3) did not suffer as a significant diminishing benefit with increasing concentration in LTLP conditions however which means that at a higher concentration,it may begin to be more effective.Each material used in this study has its own specific and technical characteristics that will help create a progressive amount of property,such as providing stability and withstanding the high-temperature and highpressure condition downhole.