Abstract:Ocean scientific drilling is an important means of scientific exploration and research of the ocean floor， and has extremely important significance in many fields such as earth science， life science， and resource exploration. Circulation Obviation Retrofit Kit （CORK） is an important supplement to ocean scientific drilling. CORK can achieve the transformation from short-term sampling to long-term dynamic observation of the seabed environment. Over the past few decades， the technological means of underwater observation equipment have also been continuously improved in this process. CORK has derived four new versions based on the initial development of CORK， which have evolved from single layer sampling to multiple layer sampling and can also perform in-situ testing. The new round of ocean drilling program led by our country is about to be implemented， and it is urgent to increase the research and development efforts of CORK technology， use our own resources and talents to build an underwater CORK observation system， and lay a solid foundation for quickly entering the ranks of world maritime powers.

Abstract:Abstract

Abstract:The potential of oil and gas resources in southwestern margin of the Sichuan Basin is abundant， however the geological structure is complex and lack of adjacent well data， making difficult drilling construction. Well Chuanmaye 1 is a shale gas geological survey parameter well deployed in the west wing of the Wuzhishan structural belt in southwest Sichuan. The designed depth of the well is 3400m， and the actual completed drilling depth is 3635m. A temporary closure was adopted when drilling to 3437.58m due to the complexity， and side tracking was carried out from 2818m to the completed drilling depth. In response to drilling difficulties， multiple key drilling technologies are summarized， including the handling of small fish accidents in large-diameter boreholes， efficient and rapid drilling with long open holes and large diameters， open hole side tracking in complex formations， and silicon potassium based polymer anti-sloughing drilling fluid systems. These technologies solved the practical problems， ensured the geological objectives， and achieved significant application effects， which can provide reference for similar drilling projects in the same region and support the new round of strategic action for prospecting breakthrough.

Abstract:Turbo drilling is a conventional drilling method in oil and gas drilling and it has been used for many years in Russia and is being studied and used in geological exploration drilling of China. However it is not enough to develop and use the small-sized turbo drill in directional drilling in China. In Russia the small-sized turbo drill （its diameter 70mm and length 650mm） has been developed and used in drilling of geological exploration holes successfully and good technical and economical results obtained. That deserves our attention.

Abstract:HDCS-2 well is a coalbed methane parameter well and production test well deployed in the Nileke Depression of the Ili Basin. Through optimizing drilling fluid parameters， high viscosity drilling fluid flushing， explosive loosening and other technical measures， the drilling complexity problems are solved including block falling， drilling tool obstruction during the tripping， and buried drilling in long open hole of the coal bearing strata， ensuring the completion of the project and the achievement of the geological objectives. Rock mineral analysis testing and scanning electron microscopy observation were conducted using samples from Well HDCS-2， and a three pressure profile was constructed based on logging data to analyze the mechanism of wellbore instability. Improved measures for subsequent projects are suggested as follows： three-section well configuration and a high shear anti collapse drilling fluid system should be adopted， high viscosity drilling fluid （drip） can be configured for well flushing when encounteres falling blocks in the well， slow drilling and tripping， optimizing the drilling tool assembly as well as equip drilling vibration hammer during drilling in coal bearing strata. The study can provide valuable practical guidance for subsequent coalbed methane drilling in the region.

Abstract:When applied to core drilling， the traditional measurement methods while drilling are limited by the blockage of the mud pulse transmission channel by the core barrel. The measurement instrument are installed behind the core drilling assembly， resulting in a large distance between the instrument and the bit， which leads to significant lag in trajectory and operating condition data， and thereforea affects the precise control of drilling process and trajectory. A near-bit measurement system while drilling for wireline coring is proposed to address this issue. The system utilizes a near-bit transmitting unit to collect operating conditions and trajectory data in real time. The collected data is transmitted via very low frequency electromagnetic waves to be stored in a receiving unit connected to the core drilling assembly’s inner tube. After core extraction， the instrument is lifted along with the core barrel for data retrieval. This paper introduces the system’s overall scheme and circuit design， moreover， experiments for short-range transmission function are carried out. The results demonstrate that the system can achieve near-bit information transmission across the core drilling assembly downhole， with a wireless transmission distance of up to 8m. These research findings can serve as a reference for researchers in the field of near-bit measurement system while drilling.

Abstract:In the process of a series of geological core drilling projects in the hilly areas of southern China， a number of technical difficulties have been encountered， including the karst cave crossing in the karst cavity area， the safe drilling in the lost return layer at the bottom of the well， the coring problem in the loose mudstone， sandstone and gravel layer， drilling difficulty in the water-sensitive formation， the stable drilling in the strong deflecting area， and the relocation difficulty in the deep cutting area. Therefore， the following technical measures were taken in response to the above difficulties： （1）the “double casing+half filling”method is taken to cross the karst caves， （2） the comprehensive technical measures of “top leakage+plugging+lubricating drilling tool”； （3） the advanced coring with casing while drilling and multi-layer casing wall protection technology， and the special sampling drilling tool with aperture convergence and the telescopic leakage joint are innovatively applied， which significantly improves the core recovery rate， （4） a low solid-phase anti-sloughing flushing fluid and strengthening solid-phase control， reducing the rotation speed and back footage， as well as rapid casing support response to ensure the hole safety； （5） the calculation method based on the mechanical model of continuous beam wire-line coring drilling tool， and the measures of low pressure lifting， drilling rig foundation reinforcement and concentricity improvement are adopted to achieve the purpose of anti-deviation and straightening； （6） the efficient scheme using drones for relocation. The results of this paper provide an important reference for drilling construction under similar environment and complex geological conditions.

Abstract:Wireline coring is a widely used technology for core drilling without tripping the drill string. However, for horizontal and deep vertical holes, process of lowering the wireline coring tools is challenging and time-consuming, in which the efficiency decreases with the hole depth. Based on hydraulic lifting principles, utilizing the power of drilling fluid circulation, using a positive circulation for core drilling and a negative circulation for hydraulic fishing, the running-in-hole and fishing system is designed based on the existed coring drill, and the H-caliber hydraulic lifting wireline coring tool is developped. The tool are tested for 3 visualized rack, 4 core drilling runs, and 2 hydraulic lifting runs in a drilling platform and experimental boreholes. As a result, the coring operation is successfully completed and the hydraulic lifting recovery of the inner tube assembly is achieved, which offers a new perspective for coring in horizontal and deep vertical holes.

Abstract:In the exploration project of the Zhaishang Gold Mine in Min County， Western Qinling Mountain， drilling work was carried out to control the main ore veins in the southern ore belt of the mining area. According to past experience， the main ore veins in the southern ore belt have steep occurrences （78°~85°） and are unstable， characterized by a southward dip in the shallow part and a northward dip in the deep part. At the same time， most areas have thick overburden layers， with intense topographic cutting， making it difficult to roads and airports construction and drilling equipment transportation. The first near-horizontal borehole in the mining area was designed， where the EP1000 portable full-hydraulic drill was used， the horizontal drill frame kit was transformed， upgraded and processed， wireline coring technology was adopted， and the construction of a near-horizontal coring borehole with a length of 216.73m was completed. This is an innovation to implement a near-horizontal borehole under the condition of water-sensitive， complex strata and continuous water gushing in the borehole. It practices the concept of green exploration and provides a reference for similar engineering projects.

Abstract:In the process of strategic mineral resources exploration and sampling， the traditional vertical hole faces some difficulties， such as high investment in a single hole and limited access to geological information， which cannot meet the needs of high efficient exploration. Therefore， a directional continuous coring technique is proposed based on wireline coring and directional drilling technology， which can efficiently and accurately obtain geological cores in underground three-dimensional space. To solve the technical difficulties of low drilling efficiency in hard rock， easily break of drilling tools and difficulty in continuous core acquisition， the effects of weight on bit （WOB）， rotation speed and deviation rate on directional coring were studied by simulation. The results show that the WOB and rotation speed are proportional to the drilling speed ，deviation rate and bend-joint stress. When the WOB is more than 30kN and the rotation speed is more than 230r/min， the deviation rate of 6°/30m can be satisfied. Based on the comprehensive consideration of drilling tool life， the preferred WOB is 25~30kN and the preferred rotation speed is 230~300r/min. The contact stress between the core and core tube becomes larger with the increase of the deviation rate， but the final contact stress will be kept within the stable range. The maximum contact stress was 514.7MPa when the deviation rate is 9°/30m， which is less than the yield strength of coring tube. The study provides theoretical support for the coordinated optimization about drilling parameters and deviation capacity of directional continuous core drilling tools.