Petroleum Drilling Techniques is supervised by China Petrochemical Corporation (Sinopec Group), sponsored by Sinopec Research Institute of Petroleum Engineering.
It aims to serve the authors and readers interested in the field of petroleum, and promote the development of petroleum engineering technology. Its scope covers oil exploitation, oil drilling, and oil drilling equipment.
Petroleum Drilling Techniques is included in CSCD, CA, EBSCO. Impact factor is 1.650.
Strength checking and design of drill strings at low temperatures are crucial to solving the technical problems of drill string in low-temperature environments such as the Arctic region. In this paper, tests were carried out at both low and normal temperatures on drill string materials G105 and S135, and their temperature-dependent parameters including tensile strength, yield strength, and impact performance, etc. were obtained. On the basis of these results, the strength design method of drill strings in low-temperature environments was proposed. The results show that both tensile and yield strength of G105 and S135 increase as the temperature decreases while the cross section reduction rate remains unchanged. In low-temperature environments, it is important to note that to ensure the safety of the drill strings, their strength design should be controlled by both stress and strain, instead of only by stress in normal temperature environments. The yield strength of drill string materials should be determined according to the strength characteristics of the materials in the wide-temperature range. The results show that this study has directive significance to guarantee the engineering design of drill strings and their safety in low-temperature environments.
With the Jiaoshiba Block in the Fuling Shale Gas Field entering into the development and adjustment period, the recoverable reserves of single wells are reduced. For the economical development of the field, it is necessary to shorten the drilling cycle and reduce the drilling cost. Therefore, with the optimum design of drilling, drilling of ultra-long horizontal sections, increasing rate of penetration by optimization of drilling parameters, a “one-trip drilling” technique based on equal-life idea, integration of drilling, reaming, and flushing in well completion, and long-term sealing technology in cementing, the drilling technology for adjustment wells of Jiaoshiba Block in the Fuling Shale Gas Field is formed. Field application results showed that the average length of horizontal sections in adjustment wells is 2 096 m, 37.8% longer than that in the first-phase drilling there. The average rate of penetration reached 9.49 m/h, 26.2% higher than that in the first-phase drilling, and the drilling cycle is 62.27 d, which is 26.0% shorter than that in the past. The percentage of wells with annular pressure lowers from 70.0% to 4.6%. The results show that the proposed key drilling technology could meet the technical needs of adjustment wells of Jiaoshiba Block in the Fuling Shale Gas Field and provide supports for a stable production and more effective development of the Fuling Shale Gas Field.
The role of silt in the volume fracturing of tight reservoirs is not yet clear, and its distribution law at the front end of the fractures is indistinct. For this reason, a dynamic fluid loss analysis device was used to establish a simulation test method for the silt distribution at the front end of volume fracturing fractures (hereinafter referred to as “volume fractures”), and the distribution law and related influencing factors were studied upon the description of fracture surface morphology. Experiment results showed that fluid loss of the sand-carrying fluid gradually took place in volume fractures, and after the fluid loss reached equilibrium, the distribution of silt retained at the front end of fractures varied considerably. Meanwhile, the pressure in the fractures gradually rose and then stabilized as the fluid loss continued. The distribution of silt at the front end of fractures can be reasonably characterized by the maximum transport distance and stable pressure. The maximum transport distance increased with widening fracture end aperture, lowering roughness of fracture surfaces, and increasing fracturing fluid viscosity. A small silt particle size also indicated a larger maximum transport distance. In addition, the stable pressure in fractures increased when the fracture end aperture decreased, the roughness of fracture surfaces increased, the fracturing fluid viscosity increased, and the silt particle size decreased. The results demonstrated that the addition of silt during fracturing can raise the pressure in fractures in that silt would plug the front end of the fractures. In addition, it would also restrain the fractures from growing too fast in a certain direction and ultimately enhance the complexity of the fracture network.
Traditional explosive perforation is subject to a short penetration distance and a compaction effect. Although the existing hydraulic perforating technology has remedied the deficiencies, it needs to cooperate with oil tubing or coiled tubing, with a long operation period and a high cost. Also, it is difficult to monitor the construction process directly and accurately only with surface pump pressure signals. With regard to this problem, research was performed on electrically controlled sidewall deep penetrating perforating technology (ECSDPPT). DC motors were selected to replace high-pressure water pumps as the energy source. Perforating tools were suspended by electric cables for transmission instead of oil tubing or coiled tubing, and the cables also transmitted electrical energy and delivered commands to control perforating operations. A real-time monitoring system was developed to monitor the drilling process into formations timely and accurately. As a result, an electrically controlled sidewall deep penetrating perforating system was built. Ground and field tests prove that the ECSDPPT enables the drilling into formations by over 2.00 m, forming a borehole with a diameter of 20.0–30.0 mm. The monitoring system can accurately calculate the actual perforating length in time by identifying and recording the electric pulse signals from a downhole Hall sensor during formation drilling. The research results demonstrate that the ECSDPPT relying on cable transmission is fast, efficient, and low-cost. It overcomes the shortcomings of conventional explosive perforation, providing a new method for connecting and reforming near wellbore formations. In addition, the monitoring system can record the drilling length and other parameters in real time during construction, effectively solving the failure of the existing hydraulic perforating technology in monitoring the working process.
The measurement point of the conventional measurement-while-drilling (MWD) tool is far distant from the bit, and the lithology and dip angle of the formation around the bit cannot be accurately judged in time. This results in a low success rate for drilling formation and a failure to meet the requirements of accurate reservoir description. Therefore, a dynamic formation scanning imaging technology based on gamma rays under high-speed conditions, which can realize real-time judgement of the formation lithology under sliding and compound drilling conditions, was studied. In addition, the method capable of accurate calculation of formation dip angles at the bit was also studied. The high-precision real-time imaging technology with near-bit gamma can image and measure the parameters of near-bit gamma, dynamic well deviation, temperature, and rotation speed in real time and provide data source for the accurate control of the bit in reservoirs. The field application shows that this technology could meet the needs of geosteering drilling for measurement data and timely adjust the drilling trajectory through the accurate description of the drilled formation, thus improving the drilling success rate of high-quality reservoirs. The result suggests that the geosteering drilling technology based on China’s near-bit gamma imaging tools deserves wide applications in drilling thin oil layers and those formations with quick dip changes.
The Arctic is rich in oil and gas resources. However, its geological and environmental factors such as low temperature, shallow hazards, permafrost, and great temperature variations in the wellbore pose many challenges to the drilling operation. For this reason, during the 13th Five-Year Plan period, Sinopec has taken the safety, environmental friendliness, and efficiency of drilling as its overall goals and focused on solving the “cold” adaptability issue of drilling equipment and tools, drilling processes and measures, and wellbore working fluids. Researches were conducted on key technologies of drilling hazard assessment and control, environmental protection, key drilling equipment and tools, and drilling processes, and wellbore working fluids. Impressive progress was made in engineering technologies such as quantitative risk assessment methods of hazards to shallow gas and gas hydrate formations, the rail drilling rigs and tools utilized at −50 °C, stability evaluation and control of borehole walls in the permafrost, and low-temperature drilling fluids and cement slurries. As a result, a key technology system of drilling in the Arctic sea has taken shape. As Arctic oil and gas development enters higher latitudes and thicker permafrost regions on land and advances to deeper waters, perennial ice, or thicker ice floes in the sea, drilling in the Arctic sea faces greater challenges and requires further progress. Therefore, it is necessary to build a complete drilling and completion technology system of drilling in the Arctic sea by improving the theories and methods and developing new key equipment and tools. This system is expected to meet the demands of efficient exploration and development of oil and gas reservoirs in the Arctic and ultimately to enhance the economic benefits and core competitiveness of China’s oil companies in international cooperation projects of oil and gas development in this area.
