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Block A has developed narrow channel sand bodies, and over 30 years of efficient development experience, the main target of oil field exploration has gradually shifted from overall exploration to the fault edges and top of oil layers where residual oil is locally enriched. The ultra short radius horizontal well technology has the advantages of small turning radius, accurate target insertion, and simple construction [1] . It has become an important method for tapping the remaining oil in narrow river sand bodies in special well types [2] . This article summarizes the formation of a narrow channel sand body tapping method that combines well seismic prediction with reservoir sand body prediction and trajectory optimization design. Reasonable main design parameters have been determined. The research results indicate that the angle between the design trajectory and the mainstream should be between 120 ° and 150 º. When the angle is 135 °, the production is highest, and the horizontal section length should be between 70m-200m. When the length is 200m, the recovery rate and economic benefits are the best. The interlayer distance should be kept above 50m, and the horizontal section position should be designed in the middle part of oil reservoir. This method was applied to 8 wells in Block A, with an average initial daily oil production of 3.5 tons and an average cumulative oil production of 1053 tons per well. The residual oil tapping effect is significant.

Shale oil and gas and other unconventional oil and gas resources adopt the development mode of cluster well group to achieve economic benefit development. Cluster well groups have the characteristics of small spacing between wellheads and limited space, and generally adjust trajectory parameters by designing individual artificial Wells one by one to meet the needs of geological target hitting and anti-collision and circumnavigation. Trajectory design affects the whole body, and the change of trajectory of one well causes all Wells on the same platform to readjust design parameters, which seriously affects the design efficiency. Therefore, on the basis of summarizing the experience of manual trajectory design, combining classical path planning algorithm and global planning algorithm, an automatic trajectory design model is established. A* path optimization algorithm and ant colony algorithm are used to construct the routing strategy method and rule set, and adapt the efficient manual guidance strategy for different risk classifications to achieve efficient automatic routing. A cluster well trajectory automatic design and routing module has been developed. Automatic trajectory design tested 15 platforms, with an average time of 60s. The efficiency of trajectory design was greatly improved, and it has important guiding significance for the development of automated drilling technology.

After nearly 30 years of exploration and development, ZD Oilfield has entered the development period of ultra-high water cut, and has encountered technical and management bottlenecks in geological reservoirs, drilling and completion, and equipment and facilities. The underground wellbore is distributed in a three-dimensional staggered spider web, the anti-collision relationship is extremely complex, the construction is difficult, and the well control safety requirements are high. ZD Oilfield mainly uses 3D trajectory design model and mechanical simulation system to optimize well trajectory, automatic directional drilling system to realize geological and engineering integration and efficient operation management, real drilling monitoring system to improve drilling engineering efficiency, and wellbore risk intelligent early warning and decision-making system to effectively reduce drilling engineering risk. Through the strict operation management and the auxiliary application of intelligent means on site, the efficiency of drilling and completion operations and the scientific decision-making of decision-making are improved, and the quality of well construction projects is improved. If the drilling difficulty continues to increase, the drilling cycle and well construction cycle will decrease from 11.89 days and 23.01 days in 2021 to 8.42 days and 19.91 days in 2024, respectively, and the cementing quality pass rate will increase from 74.18% to 97.41%. At the same time, the drilling and completion problems of the long and stable slope section of the highly difficult and large deviate well were overcome.

The oilfield has entered the ultra-high water cut period, the distribution of remaining oil is scattered, and it is difficult to tap the potential. On the plane, affected by sand body distribution and well pattern production objects, sand body perforation does not correspond to each other, forming residual oil with imperfect injection production relationship; The residual oil formed in the retention area at the edge of the fault due to the influence of fault shielding. Vertically, affected by the heterogeneity, interlayer and rhythm in the layer, the bottom of the thick oil layer is strongly washed, the middle is moderately strongly washed, and the top is weak and not washed. The production difference is large, and the remaining oil mainly exists at the top of the oil layer. The remaining oil with imperfect injection production relationship and special parts is tapped through ultra short radius horizontal wells to improve oilfield development efficiency.

The ultra-shallow heavy oil reservoir in Chunfeng Oilfield has become an important position in increasing reserves and production. Vertical wells have low production and poor benefits. The development engineering technology of horizontal wells faces many technical problems. Aiming at the drilling problems of ultra-shallow heavy oil horizontal wells, research and application have been carried out from the aspects of drilling engineering optimization design and shallow soft formation trajectory control. Shallow heavy oil cementing and completion and key drilling and completion technologies suitable for the efficient development of ultra-shallow heavy oil in the Neogene of Junggar Basin have been formed. The field application results show that the technology has well supported the development of ultra-shallow heavy oil reservoirs and has accumulated many construction records, such as the shallowest vertical depth, the largest vertical ratio, and the shortest drilling and completion period. The new production capacity of 50 thousand tons has strongly supported the benefit and production increase of Shengli exploration area in the Junggar Basin.

The current well planning process for operators is capital-intensive that takes time and has a lot of discrete, disconnected steps. Well planners and engineers dedicate a significant amount of time and effort to analyze sub-surface and offset well data for trajectory planning, casing policy selection, casing design, torque & drag, hydraulics, time & cost analysis etc. For development wells and unconventional wells, it is a common scenario for drilling engineers to have a very clear understanding of how the well design shall look like as the oil & gas field is extremely well familiar. As an initial step towards standardization, a review and study of several well design processes were performed by interviewing several engineers, all around the globe. The study revealed that even though every engineer had their own way of working, there was an inherent workflow that could be standardized. This standardized workflow was then outlined with user experience development techniques to cater to the generic steps that well planners, engineers and managers had described. With implementation of this standardized workflow and UI/UX supported process, the next step was to build a cloud native solution which supports micro-services-based engineering calculations in the backend. This allowed to implement speed and scalability in the solution which can cater to various personas in a team. The next step was to automate the process for a development field. This was achieved by applying checkpoints in the workflow to identify an exploratory well vs. a development well, before calling a microservice. For a development field, the microservice architecture identifies the design aspects of an existing well and incorporates similar well trajectory turn points, casing policy, casing design, BHA, fluids, operational parameters etc. while honoring the surface hole location, targets, and datum reference of the new wells to be planned. This technique helped to not only automate the engineering calculations but also speed up the entire process of designing each well in under a minute. Apart from engineering calculations, a planning workflow is never complete without team governance, approvals from peers and supervisors, testing various scenarios and creating reports. As these tasks are an inherent part of the planning cycle, they were also incorporated in the workflow. The UX design process techniques ensured that these supplementary tasks were a part of the main workflow and did not interfere with the calculations. The solution has shown a tremendous increase in the work efficiency of user by reducing the planning efforts from days to minutes. The users can now focus on wells using management by exception as the entire design process can be automated. This also eliminates any unnecessary data entry and avoids errors.

Advances in the field of material engineering, computerization, automation, and equipment miniaturization enable modernization of the existing technologies and development of new solutions for construction, inspection, and renovation of underground pipelines. Underground pipe installations are used in the energy sector, gas industry, telecommunications, water and sewage transport, heating, chemical industry, and environmental engineering. In order to build new pipeline networks, dig and no-dig techniques are used. Horizontal Directional Drilling (HDD) is one of the most popular trenchless technologies. The effectiveness of HDD technology application is mostly determined by its properly designed trajectory. Drilling failures and complications, which often accompany the application of the HDD technology, result from poor design of the well path in relation to the existing geological and drilling conditions. The article presented two concepts of Horizontal Directional Drilling well path trajectory design: Classic sectional, which is a combination of straight and curvilinear sections, and a single-section chain curve trajectory (catenary). Taking into account the advantages and disadvantages of the catenary trajectory relative to the sectional trajectory, the author’s solution was presented, which was the implementation of the sectional trajectory with a maximum shape similarity to the catenary trajectory. The new approach allowed us to take advantage of a chain curve trajectory and was easier to implement using the available technology. The least squares method, based on deviations from a catenary trajectory, was set as the matching criterion. The process of searching for a trajectory, being a combination of straight and curvilinear sections as similar as possible to a catenary-type trajectory, was carried out using two methodologies: State space search and a genetic algorithm. The article shows the pros and cons of both optimization methodologies. Taking into account the technical and technological limitations of HDD drilling devices, a new approach was proposed, combining the methodology of state space search with the genetic algorithm. A calculation example showed the application of the proposed methodology in an engineering design process.

Current methods for designing three-dimensional trajectories rarely account for complex formation constraints, focusing primarily on geometric relationships. However, trajectory adjustments are often necessary during drilling operations. These field adjustments typically lack systematic optimization, resulting in suboptimal trajectories. This study introduces a novel trajectory optimization framework that integrates formation fitness for curve construction and proactive anti-collision trajectory adjustment (PACTA). The framework begins by incorporating PACTA and optimizing the initial trajectory to minimize total measured depth (TMD) using a genetic algorithm. Subsequently, a second optimization phase identifies curve sections passing through formations with low build-up fitness, automatically splitting them into combinations of curves and straight lines. Dynamic trajectory equations are then constructed based on these adjustments, and the final trajectory is optimized accordingly. Case studies demonstrate that the proposed method effectively adjusts curve positions in the presence of multiple formations with low build-up fitness while avoiding wellbore collisions. The approach achieves an average 10% reduction in total drilling time when minimizing TMD and an average 19.7% reduction in drillstring torque when torque minimization is prioritized. This new trajectory design method is expected to significantly reduce well construction costs.

Borehole trajectory optimization is a key issue in oil and gas drilling engineering. The traditional wellbore trajectory design method faces great challenges in optimizing the trajectory length and complexity, and it is difficult to meet the actual engineering requirements. In this paper, the three-stage wellbore trajectory optimization problem is studied, and a multi-objective optimization model including two objective functions of trajectory length and trajectory complexity is constructed. In this paper, an improved multi-objective particle swarm optimization algorithm is proposed, which combines the clustering strategy to improve the diversity of solutions, and enhances the local search ability and global convergence performance of the algorithm through the elite learning strategy. In order to verify the performance of the algorithm, comparative experiments were carried out using classical multi-objective benchmark functions. The results showed that the improved algorithm is superior to the traditional method in terms of diversity and convergence of solutions. Finally, the proposed algorithm was applied to the actual three-stage wellbore trajectory optimization problem. In summary, the research results of this paper provide theoretical support and engineering practice methods for wellbore trajectory optimization, and serve as an important reference for further improving the efficiency and quality of wellbore trajectory design.

Low-permeability to ultralow-permeability reservoirs of the China National Petroleum Corporation are crucial to increase the reserve volumes and the production of crude oil in the present and future times. This study aimed to address the two major technical bottlenecks faced by the low-permeability to ultralow-permeability reservoirs by a comprehensive use of technologies and methods such as rate-controlled mercury injection, nuclear magnetic resonance, conventional logging, physical simulation, numerical simulation, and field practices. The reservoir characteristics of low-permeability to ultralow-permeability reservoirs were first analyzed. The water flooding development adjustment mode in the middle and high water-cut stages for the low-permeability to ultralow-permeability reservoirs, where water is injected along the fracture zone and lateral displacement were established. The formation mechanism and distribution principles of dynamic fractures, residual oil description, and expanding sweep volume were studied. The development mode for Type II ultralow-permeability reservoirs with a combination of horizontal well and volume fracturing was determined; this led to a significant improvement in the initial stages of single-well production. The volume fracturing core theory and optimization design, horizontal well trajectory optimization adjustment, horizontal well injection-production well pattern optimization, and horizontal well staged fracturing suitable for reservoirs with different characteristics were developed. This understanding of the reservoir characteristics and the breakthrough of key technologies for effective development will substantially support the oil-gas valent weight of the Changqing Oilfield to exceed 50 million tons per year, the stable production of the Daqing Oilfield with 40 million tons per year (oil-gas valent weight), and the realization of 20 million tons per year (oil-gas valent weight) in the Xinjiang Oilfield.