well trajectory
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2021 ◽  
pp. 90-102
Author(s):  
S. K. Sokhoshko ◽  
S. Madani

This article discusses the effect of wellbore trajectory on the flow performance of a horizontal cased and perforated gas well. We used a coupled well-reservoir flow model, taking into account the nature of the flow, and local hydraulic resistances of the wellbore, and thus determined the pressure and mass flow distribution along the horizontal wellbore for several types of trajectories, including undulated and toe-up trajectories. The simulation results showed the effect of horizontal gas well trajectory type on its flow rate and the importance of considering pressure distribution to optimize well design.


2021 ◽  
Author(s):  
Yaowen Liu ◽  
Wei Pang ◽  
Jincai Shen ◽  
Ying Mi

Abstract Fuling shale gas field is one of the most successful shale gas play in China. Production logging is one of the vital technologies to evaluate the shale gas contribution in different stages and different clusters. Production logging has been conducted in over 40 wells and most of the operations are successful and good results have been observed. Some previous studies have unveiled one or several wells production logging results in Fuling shale gas play. But production logging results show huge difference between different wells. In order to get better understanding of the results, a comprehensive overview is carried out. The effect of lithology layers, TOC (total organic content), porosity, brittle mineral content, well trajectory is analyzed. Results show that the production logging result is consistent with the geology understanding, and fractures in the favorable layers make more gas contribution. Rate contribution shows positive correlation with TOC, the higher the TOC, the greater the rate contribution per stage. For wells with higher TOC, the rate contribution difference per stage is relatively smaller, but for wells with lower TOC, it shows huge rate contribution variation, fracture stages with TOC lower than 2% contribute very little, and there exist one or several dominant fractures which contributes most gas rate. Porosity and brittle minerals also show positive effect on rate contribution. The gas rate contribution per fracture stage increases with the increase of porosity and brittle minerals. The gas contribution of the front half lateral and that of latter half lateral are relatively close for the "upward" or horizontal wells. However, for the "downward" wells, the latter half lateral contribute much more gas than the front half lateral. It is believed that the liquid loading in the toe parts reduced the gas contribution in the front half lateral. The overview research is important to get a compressive understanding of production logging and different fractures’ contribution in shale gas production. It is also useful to guide the design of horizontal laterals and fractures scenarios design.


2021 ◽  
Author(s):  
Khaqan Khan ◽  
Mohammad Altwaijri ◽  
Sajjad Ahmed

Abstract Drilling oil and gas wells with stable and good quality wellbores is essential to minimize drilling difficulties, acquire reliable openhole logs data, run completions and ensure well integrity during stimulation. Stress-induced compressive rock failure leading to enlarged wellbore is a common form of wellbore instability especially in tectonic stress regime. For a particular well trajectory, wellbore stability is generally considered a result of an interplay between drilling mud density (i.e., mud weight) and subsurface geomechanical parameters including in-situ earth stresses, formation pore pressure and rock strength properties. While role of mud system and chemistry can also be important for water sensitive formations, mud weight is always a fundamental component of wellbore stability analysis. Hence, when a wellbore is unstable (over-gauge), it is believed that effective mud support was insufficient to counter stress concentration around wellbore wall. Therefore, increasing mud weight based on model validation and calibration using offset wells data is a common approach to keep wellbore stable. However, a limited number of research articles show that wellbore stability is a more complex phenomenon affected not only by geomechanics but also strongly influenced by downhole forces exerted by drillstring vibrations and high mud flow rates. Authors of this paper also observed that some wells drilled with higher mud weight exhibit more unstable wellbore in comparison with offset wells which contradicts the conventional approach of linking wellbore stability to stresses and rock strength properties alone. Therefore, the objective of this paper is to analyze wellbore stability considering both geomechanical and drilling parameters to explain observed anomalous wellbore enlargements in two vertical wells drilled in the same field and reservoir. The analysis showed that the well drilled with 18% higher mud weight compared with its offset well and yet showing more unstable wellbore was, in fact, drilled with more aggressive drilling parameters. The aggressive drilling parameters induce additional mechanical disturbance to the wellbore wall causing more severe wellbore enlargements. We devised a new approach of wellbore stability management using two-pronged strategy. It focuses on designing an optimum weight design using geomechanics to address stress-induced wellbore failure together with specifying safe limits of drilling parameters to minimize wellbore damage due to excessive downhole drillstring vibrations. The findings helped achieve more stable wellbore in subsequent wells with hole condition meeting logging and completion requirements as well as avoiding drilling problems.


2021 ◽  
Author(s):  
Atul Kumar Anurag ◽  
Adel Alkatheeri ◽  
Alvaro Sainz ◽  
Khalid Javid ◽  
Yaxin Liu ◽  
...  

Abstract This paper discusses a holistic combination of advanced formation evaluation techniques with pressure testing and reservoir navigation services to mitigate uncertainty related challenges in real time and successfully drill & place ERD laterals targeting Jurassic carbonate reservoirs. A meticulously planned approach to navigate the well trajectory by tracking the desired properties, informed decision-making while drilling and accurate data acquisition for aiding appropriate selection and placement in-flow control device (ICD) in lower completion design and future reservoir management contributed to the success of these complex wells in carbonate reservoirs. The first well in this study, involved drilling and evaluating a long lateral section as single oil producer targeting a carbonate reservoir. While no tar presence was expected, a combination of density, neutron porosity and nuclear magnetic resonance (NMR) logs while drilling resulted in identifying a deficit NMR porosity when compared to density porosity. Deployment of a formation pressure testing while drilling (FPWD) tool enabled measurement of the formation mobility and validate the presence of a tar. Using the same combination of measurements in the subsequent wells for delineating the tar enabled accurate planning of injection wells on the periphery of the field. Approximately 3 days were saved compared to the first well where the drill string had to be POOH to run-in with FPWD service. Hence, having FPWD tool in the same string helped in confirming the formation mobility in real time to call for critical decision making like changing the well trajectory or calling an early TD. Across all the wells drilled in this field, the formation pressure, mobility and porosity measurements provided valuable input for optimum ICD placement and design. Successful identification of unexpected tar resulted in substantial rig time savings, accurate planning of asset utilization and added confidence in design and placement of lower completions by utilizing LWD data. Benefits of integrated data and services combination became clear for applications involving advanced reservoir characterization and enhanced well placement in complex carbonate reservoirs. From the offset wells, a tar was seen in deeper formations but the integration of LWD NMR and mobility data from this well confirmed the presence of a tar within the zone of interest. The study established a cost-effective workflow for mitigating uncertainties related to tar encountered while drilling extreme ERD laterals in an offshore environment where any lost time results in significant increase in expenditures during the development phase. A systematic approach to tackle these uncertainties along with acquisition of critical data for the design & placement of completion results in optimum production from the reserves.


2021 ◽  
Author(s):  
Danis Nazipov ◽  
Pavel Shpakov

Abstract Today, one of the most modern and successful geosteering methods in terms of net to gross value (NTG) is a proactive geosteering. The purpose of this article is to share the experience of using Remote Boundary Detection Tools to solve various geological problems and describe the ways of using the data from it. The method provides the ability to detect the approaching boundary (usually reservoir top) with resistivity contrast before entering it with the bit or BHA sensors. It allows to adjust well trajectory proactively and, therefore, increase Net to gross ratio. The article shows the ways to implement global experience in horizontal wells drilling and proposes ways to reduce the cost of well construction without elimination of High-Tech equipment in BHA. The article explains the methods of interpreting the output data from the tool that can determine the approach to one or several boundaries with resistivity contrast.


2021 ◽  
Author(s):  
Anton Yurievich Bokarev ◽  
Dmitriy Mikhailovich Yezersky ◽  
Anton Yurievich Filimonov ◽  
Ivan Romanovich Dubnitsky ◽  
Vladislav Viktorovich Vorobiev

Abstract Productive deposits of the Turonian age as part of the Kuznetsovskaya Formation are cover the eastern part of Western Siberia (Figure 1), but until recently they were not of wide industrial interest. Today, most of the gas reserves in Western Siberia are produced in the Cenomanian deposits, which are in the stage of declining production. The productivity of the deposits above Cenomanian layer has been established in many fields where the Cenomanian formations are productive. In general, in Western Siberia in the Turonian deposits, there are more than 3 trillion cubic meters of gas, which allows us to consider them as high-potential sources of gas reserves. The main difficulties in the industrial development of Turonian deposits are reduced permeability, high dissection, high content of clay fraction, high macro- and microheterogeneity of the reservoir, inconsistency of effective thicknesses in plan and section. In turn, the relatively low temperature of the reservoir predetermines the operation of the field in a mode close to hydration (Avramenko et all., 2019). Under these conditions, a good petrophysical baseline is essential to assess the exploration potential of the assets and design the development of the reservoir. Shaly gas-saturated formations are not a simple object for petrophysical modeling. Adding to this the low quality of the core material caused by the weak cementation of shallow deposits, we get a very nontrivial problem. On the other hand, modern horizontal well development scenarios dictate their requirements for petrophysical models. In other words, the petrophysical model must maintain its stability for any well logging regardless of the well trajectory (vertical or horizontal) and the logging method conveyance (wireline or while drilling). The authors of the paper carried out work on the development of a universal petrophysical model of the Turonian reservoir, for one of the fields in the region of the north of Western Siberia, based on a modern extended GIS complex.


2021 ◽  
Author(s):  
Askhat Radikovich Usmanov ◽  
Anton Mikhailovich Shishkin ◽  
Alexander Sergeevich Merzlyakov ◽  
Jalal Lalash Ogli Karimov ◽  
Anton Valeryevich Fedotov ◽  
...  

Abstract Casing drilling technology, as an alternative to conventional drilling, has been known for a long time. This method is mainly used for wells with geological complications, such as lost circulation or wellbore instability of various nature. By using drilling on a string for a section or part of it, the problem interval is immediately cased, eliminating the time spent on additional operations, such as pulling the bottom hole assembly (BHA), wiper trips and running the casing. Thus, this allows to reduce the time for well construction, reduces the risk of accidents and non-productive time associated with the complication zone. Casing drilling has become widely for drilling vertical surface conductors and technical casing with a drillable shoe, as well as for drilling with retrievable BHA in inclined sections for 324- and 245-mm casing. The aim of this work was to perform directional drilling on a 178mm production casing in an interval where the client had geological problems associated with running casing due to a zone of rock collapse. The uniqueness of the task lies in the fact that no one in the world has yet performed drilling on a casing with a building inclination and landing into a horizontal plane. It was necessary to follow the designed well trajectory, to build inclination from 67 to 85 degrees with the planned dogleg severity of 1 degree / 10m.


2021 ◽  
Author(s):  
Yan Ding ◽  
Meng Cui ◽  
Hai ge Wang ◽  
Zhao Fei ◽  
Xiao yan Shi ◽  
...  

Abstract While drilling into fracture zones, lost circulation frequently occurs, resulting in a waste of productive operation severe cases, the well's destruction. However, due to complex development mechanisms and high heterogeneity, identifying and predicting fractures is extremely difficult. This study proposes a new drilling loss prevention idea to evaluate fractured lost circulation risk using seismic and wellbore data by a novel neural network. The approach works in two steps. First, the fracture anisotropy of a lost circulation sample curve is computed and interpreted using well logs. Second, using seismic attributes as constraints, a novel neural network is used to develop a prediction model. The field application in the Sichuan basin verifies the method's efficacy and confirms the method's ability for predicting lost circulation probability both along the well trajectory and in regions away from the drilled wells.


2021 ◽  
Author(s):  
Robert E. Grimes ◽  
Jake Drew ◽  
Aulia Hamdani Feizal ◽  
Eka Pambudi Riambomo ◽  
Ridwan Durachman

Abstract Santan is a mature gas field in East Kalimantan, Indonesia, where infill wells are being drilled to increase production rates. A crowded offshore platform in the Santan Field increases well trajectory complexity and presents a heightened risk of wellbore collision issues. The high number of wells on this directional pad in the shallow water drilling environment results in densely populated existing conductor pipe. Thorough drilling assessments and anti-collision directional drilling mitigation practices are key to successfully executing safe and reliable drilling operations. To further mitigate the likelihood of a well control situation resulting from a collision with a neighboring conductor or casing, a 17.5 in. IADC Classification 115 Steel Tooth (ST) rolling cone bit with special heel technology was utilized in the Santan field. This is the first time this technology has been applied in Asia Pacific. The ST bit employs continuous disk shaped heel rows on all three cones rather than conventional ST chisel shaped heel row teeth which have multiple sharp cutting edges. The special disk heel rows are designed to deflect off casing in the event of a collision in order to minimize damage to conductor or casing. The use of the special disk heel technology bit has yielded positive results to date. The bits have successfully and safely drilled in a critical zone where the center-to-center distance between slots was as low as 1m. The drilling performance and well trajectory targets were achieved. Reduced drilling parameters were used as per anti-collision and lost circulation practices, however, the overall rate of penetration (ROP) and directional behavior with the special disk heel bit was similar to conventional ST bits used in offset wells without collision risks. Turn and build rates of up to 4.8°/100 ft were achieved on a bent motor bottomhole assembly, while the average distance to the plan at the end of the section was only 10.59 ft. A series of laboratory casing collision tests was conducted during the development of the special disk heel bit which demonstrated a 75-80% reduction in casing collision damage as compared to a conventional IADC 115 ST bit. Overall, this technology minimizes the detrimental effects should a collision occur, without sacrificing ROP or steerability performance. The special disk heel ST bit has proven to cause significantly less damage to casing from a collision event than any other bit type – ST, tungsten carbide insert (TCI), or PDC bits, while still providing excellent ROP and steerability in soft formation, shallow water applications. This technology allows operators to more confidently place additional wellbores in crowded offshore template environments for greater field development from a single platform.


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