Abstract:The global unconventional oil and gas field development is currently facing continued low-price challenges， therefore， well productivity and well construction efficiency improvement is becoming particularly important. There are two major developing trends in drilling： one is the lateral length is getting longer and longer to achieve higher reservoir contact volume and therefore increased well productivity； the other is the drilling efficiency continues to improve to achieve higher economic efficiency by reducing well construction time and costs. Accordingly， it poses great challenges to horizontal well drilling， especially the ultra-long horizontal wells. It is particularly important to develop a complete fast drilling technology system for effective ROP improvement and well construction costs reduction. In recent years， Chinese unconventional oil and gas fields had made major breakthroughs in fast-drilling technologies but lack of effectiveness and repeatability. The North America unconventional oil and gas development has long history， and its fast-drilling technologies are mature. Wells with lateral length of more than 3000m are very common and the drilling performance is clearly better than those similar wells in China. This paper focuses on the advanced drilling equipment， drilling design， downhole tools， drilling parameters and operational practices of North American ultra-long horizontal wells， supported with two case studies from the Permian Basin with actual drilling data. The purpose of this paper is to summarize the fast-drilling technologies in North America， discuss and share the application results for reference for the Chinese unconventional oil and gas fields development.

Abstract:Well Yunxuandi-1， a small-diameter shale gas survey well in eastern Yunnan， was drilled through mainly Cambrian， Devonian， Carboniferous and Permian strata. In the process of drilling， a lot of complex downhole situations were encountered such as severe leakage， fracture leakage， rock breaking and stone falling. To this end， multiple relevant measures， such as drill bit and drilling fluid optimization， combination of various plugging measures， blind drilling， sidetracking， were adopted to solve the problems of severe leakage and block falling caused by large karst caves and longitudinal fractures in massive limestone formation， which avoided wellbore failure caused by excessive drilling fluid density， and improved mechanical efficiency. The drilling experience can provide reference for future drilling of complex limestone strata in eastern Yunnan.

Abstract:With the deep development of Sulige Gas Field， the construction of large well clusters and three-dimensional horizontal wells is increasing gradually， which increases the difficulty on trajectory control. Drilling cluster type three-dimensional horizontal wells faces many issues， such as high collision risk； difficulty in slide-drilling due to large friction torque with the long build-up well section； and difficult WOB transfer， wellbore instability and cleaning difficulty due to the long horizontal section and unstable production layer. In view of these problems， a complete set of technical countermeasures have been formed through optimization of the drilling design and the drilling stem， adoption of the salt water drilling fluid system， optimization of the mud motor， and field technical management and the driller’s careful response， which has led to the safe and efficient completion of drilling works.

Abstract:In light of the difficulties in secondary cementing of ?88.9mm small casing set in ?139.7mm production casing in the Changqing Oilfield， such as small annulus， high pumping pressure， thin cement ring， uncertainty in sealing integrity for the follow-up treatment measures， poor wellbore boundary， poor cement bonding at the two boundaries， technological innovation and improvement was conducted to develop a low-friction， pressure-resistant and leak-proof cement slurry system， and a thermosetting resin cement slurry system. They were combined with the independently developed boundary enhancing acid flushing fluid and the cementing plugging fluid system to form the slim casing cementing fluid system in Changqing Oilfield. With optimization of the reliable cementing accessories and the structure of the small casing cementing string， and use of the single-stage cementing process according to the principle of balanced pressure cementing， the slim casing secondary cementing process has been developed. Field application in 10 wells showed the rate of excellent cementing quality up to 95% with significant stimulation effect， which can provide strong technical support for the potential enhancement of the old wells and the management of casing damaged wells in Changqing Oilfield.

Abstract:The well designed for geothermal exploration and production in Daying， Yuanping was completed at depth of 3088m. To find out hydrogeological parameters and water recharge of 494~3088m formation， it was divided with four pumping test sections based on core and logging data； meanwhile， the target aquifer needed to be restored as much as possible after tests. According to the principle of “multi-level sealing in a single diameter hole”， a new water sealing process was designed with the water-stop tray for inside-pipe sealing and the canvas umbrella for outside-pipe sealing. This process simplifies the well structure and avoids clogging caused by dropping clay balls， injecting cement， etc. from outside the pipe. Field use shows that this process meets the water-sealing requirements of hydrogeological pumping tests， and can provide reference for similar projects.

Abstract:Under the action of high temperature plasma arc， high voltage electric pulse will produce thermal stress which can exceed the strength limit of rock， and break rocks， in particular hard rocks with obvious performance. This paper introduces the rock breaking mechanism of electric pulse. Based on the experimental data of Selfrag high-voltage electric pulse rock breaking， a simulation model of the needle electrode structure is established by using COMSOL Multiphysics simulation software. The influence of voltage， mineral composition and porosity on the distribution of electric field intensity in rock is studied. The results show that the distribution of electric field intensity is different with different applied voltage； the electric field distorts at the boundary of different mineral components， and the greater the change of relative permittivity of different mineral components， the more obvious the distortion is. Rock breaking with high voltage pulse occurs preferentially at the interface of different mineral components， and rock can be decomposed into various minerals depending on its composition. The presence of pores in the rock distorts the electric field around it； and the larger the porosity is， the easier electric breakdown the rock is.The research conclusion can provide reference for the selection of rock breaking parameters of drilling by high voltage electric pulse.

Abstract:Loose sediment is the main material form of overburden， which is the main research object to promote green development and build ecological civilization. With the continuous enrichment of research content， the depth and accuracy in overburden survey are constantly increasing. Whether the accurate and in-situ pollution-free sampling of loose sediments can be realized is one of the key factors restricting the follow-up research. Based on the drilling survey practice in the Xilin Gol League-Tongliao area， this paper combines wire-line coring drilling technology and advance coring technology with film-forming wall protection drilling fluid technology to improve the stability of hole wall and the integrity of loose core so as to solve the technical difficulties restricting the drilling sampling of thick overburden， and provide technical support for loose sediment survey in related fields.

Abstract:The strata in the Sargan area of Tianshan Mountains in southwest Xinjiang are extremely fractured and complex. In recent years， many holes have been drilled through broken and lost circulation formation where falling blocks， stuck drilling and hole collapse happened frequently. In reference to a drilling case in this area， this paper introduces the treatment process and cautions for treatment of the serious drilling accident of drilling string falling-off due to breaking of the coring wire line in the fractured complex strata. With analysis of the accident， guided reaming was adopted to deal with the complex accident effectively. As a result， the hole was successfully finished with the required geological data obtained， and some economic losses were recovered.

Abstract:The lithology of the Xiangyangping uranium deposit in Guangxi is mainly granite with strong abrasiveness， and some formation is complex with densely developed structural fissures， broken rocks， strong chloritization and kaolinization， leading to drilling difficulty. With the use of diamond wire line core drilling technology and process， continuous improvement measures have been taken to solve the problems encountered in drilling， such as low drilling efficiency， unstable hole wall， short service life of the diamond bit and bending of the drilling hole. Field practice has proved that the drilling technology and process has the advantages of high drilling efficiency， high core recovery and low labor intensity， which can accumulate valuable experience for drilling of granite and complex strata.

Abstract:Most of the boreholes in the Xiling exploration area are located at the seaside. During drilling， seawater or seawater intruded water is used for slurry making. The traditional fresh water mud system doesn’t perform well or even fail in carrying cuttings， lubricating drilling tools and protecting hole walls， which affects smooth drilling progress. The traditional mud materials were innovated with introduction of new seawater salt resistant mud materials to develop the seawater drilling fluid composition with better performance for the mining area； thus eliminating safety hazards and improving drilling efficiency.

Abstract:XD-40 drilling rig， the technical equipment for deep mineral resources exploration， has been applied to the construction of geothermal exploration wells in Xiongan New Area， and successfully completed the drilling task of Well D13， with the drilling depth of 2506.14m and the drilling diameter of ?152.4mm. This paper mainly introduces the construction of D13 well from the aspects of project overview， equipment characteristics， operations and accident treatment， and summarizes the performance of XD-40 in overall performance， accident treatment， multi-process adaptability， and energy consumption. It has been proved that XD-40 drilling rig has the advantages of safety， reliability， intelligent control， energy saving and environmental protection， and can be applied to the construction of geothermal wells with depth of 2500~2800m.

Abstract:Liaohe Oilfield is an old oilfield with more than 40 years of development history. Its heavy oil production accounts for half of the crude oil production. Its heavy oil recovery technologies mainly include steam huff and puff， steam flooding， SAGD and fire flooding. With heating the temperature of crude oil to reduce its viscosity， casing will be damaged in varying degrees after several rounds of production. Casing shaping technology is one of the main technologies for casing repair. Casing deformation is prone to occur with the increase of oilfield development time. In order to ensure the production of oil fields， casing needs to be repaired by the casing reshaping process. In this paper， a new type of mechanical and hydraulic compound casing reshaping technology is developed by combining the conventional pear-shaped reshaping process with the hydraulic reshaping process. Through the optimization design of the expansion head structure， including extension of the length of the tapered guide shoe section and reduction of the taper of the guide shoe section， improvement of the steel bead strength with alloy steel used for the expansion head， which makes the steel bead strength much higher than P110 steel level， the sticking problem in the process of hydraulic reshaping construction due to the low strength of the expansion head and easy is solved. Moreover， by creatively putting forward the structure with the rigid drill collar string ahead of the expansion head， the difficulty in passing the hydraulic reshaping tool through the perforated interval has been solved successfully. The new casing reshaping technology provides fast operation of pear-like reshaping technology and strong reshaping ability of hydraulic reshaping technology. The comparison of the pear-like expanding tube expander and composite casing shaping technology shows that mechanical-hydraulic composite casing shaping technology can greatly shorten the operation time， and has good application prospect and promotional value.

Abstract:In light of the problems such as insufficient single hole depth， short effective hole interval， low drilling efficiency， small drilling diameter， etc. with conventional drilling from the working face at Liuhuanggou Coal Mine， it was proposed to use the narrow compact ZDY4000LD （C） type crawler drill， and directional drilling tools and accessories such as the second generation MWD system （YHD2-1000 （A）） to drill cross-bed directional long holes so as to improve drilling accuracy， and increase hole depth and drilling diameter， while reduce increased working face gas emission problems due to coal mining. Four directional， large diameter， cross-bed long holes were field test-drilled with depth over 300m， hole completion rate up to 100%， the deepest depth of 399m， the largest diameter of ?193mm， the total drilling footage of 1581m， average depth of 395.25m， and significant increase in borehole gas extraction efficiency. Among them， the No.3 borehole provided the maximum extraction mixed flow rate of 8.3m³/min， the maximum extraction net volume 1.6m³/min， and the gas extraction concentration 51%， resulting in significant gas extraction effect.

Abstract:There are a large number of glacier relics in Southeastern Tibet， forming a large number of loose accumulations， which are prone to disasters. There are many voids in the moraines， and the structures are unstable. The technology of grouting reinforcement by steel screen pipe for moraines was studied with discussion of the construction technologies， the reinforcement mechanism， as well as the design method. The numerical simulation was also implemented. The field tests were performed， and the results showed that the effective reinforcement radius of shallow surface grouting of moraine is 20~55cm； the soil cohesion， internal friction angle and compression modulus improved after grouting reinforcement； the vertical permeability coefficient of the soil becomes smaller； the preferred grouting pressure is 0.5 to1.0MPa， the water/cement ratio 2、1， the ratio of the grouting hole spacing to the effective reinforcement radius not greater than 8. Through field tests， a screen pipe grouting process has been formed on the basis of the 3.5 cubic air compressor， YT28 rock drill， hollow self-drilling bolt and pneumatic grouting machine， which is suitable for inconvenient traffic and poor construction conditions.

Abstract:With the rapid development of modern society， energy demand and environmental problems are gradually aggravating， ground source heat pump systems can be used to extract shallow ground temperature-a clean energy source to achieve the goals of energy conservation， emission reduction and full utilization of resources. An important factor affecting the efficiency of geothermal energy extraction in ground source heat pump technology is the development and application of backfill materials. This article reviews the thermal conductivity， mechanical properties and construction performance of backfill materials in ground source heat pump technology， as well as their current problems and development trends. It points out that the current research and development of thermal conductivity of backfill materials can achieve higher thermal conduction efficiency， but it often affects the mechanical strength and other physical properties of the materials， and increases its construction difficulty. Phase change materials may be the key to solving the performance defects of backfill materials； in addition， with the development of science and technology， the combination of numerical simulation and experimentation can greatly improve theoretical innovation and engineering benefits.

Abstract:In recent years， floating accidents in building engineering have been reported frequently， and the existing judicial precedents are extremely unfavorable to the investigation and design units. Starting from the principle of anti-floating， based on the analysis of existing cases， combined with the requirements of relevant standards and problems in practice， this paper puts forward suggestions on the concerns of investigation and design documents on anti-floating. The dynamic and process explanation of “basin effect” is given for the first time in this paper. The basin-in-basin technical measures have been put forward for the first time. Automatic monitoring， alarm systems， among others are suggested for large-scale foundation pits. This paper is intended to clarify the investigation and design conditions， avoid engineering accidents， legal disputes and the adverse results caused by them， which can be used for reference by investigation and design units.

Abstract:The main chemical components of construction engineering waste mud produced by different formations and different processes in the Wuhan area were analyzed by spectrograph， and the separation effect of waste mud was evaluated by orthogonal tests of filtration， vacuum filtration， centrifugation and different flocculants with the turbidity and clear liquid rate as the main evaluation indexes. The results showed that the waste mud was mainly composed of organic substance； the filtrate obtained by filtration had lower turbidity but less clear liquid rate； more supernatant could be obtained by vacuum filtration； most of the waste mud except for ultra-fine particles could be treated by centrifugation； the orthogonal test showed that better effect was obtained with cationic flocculant （PAM） treating waste mud.

Abstract:Testing of bearing capacity and integrity of foundation piles is the key step in acceptance inspection of concealed works. Usually， the testing method is planned in the design stage of pile foundation with the testing facilities placed or the ground treated in the construction stage， so as to facilitate the smooth execution of subsequent testing. The large diameter and super-long pile has high testing requirements due to the large design bearing capacity and complex pile conditions； thus， the principle of synchronous testing and design should be followed. On a project in Tianjin， the very negligence of prior design of foundation pile testing led to difficulty in large diameter and super-long pile testing. Though the conditions were limited， with professional technical analysis and many years of practical experience， and through formulation of testing methods and measures according to local conditions， the author has completed the bearing capacity verification test on large diameter and super-long piles with large tonnage surcharge by the step-by-step loading method， and integrity test on large diameter and super-long piles by combination of the low-strain method and the high-strain method， which provides valuable experience for similar works.