scholarly journals New Risk Assessment Method of Gas Influx Based on Fifteen Example Wells

2019 ◽  
Vol 2 (1) ◽  

With the increase of global deepwater drilling, the scale of the deepwater drilling contract market continues to expand, and the depth of the drilling operations constantly refreshes the record. At the same time, the drilling environment and related geological conditions becomes more and more complex, which leads to the increase of the risk in the operation of deepwater drilling. After the happening of “Deepwater Horizon Accident” in the Gulf of Mexico, the prevention and control of blowout has become an urgent problem to be solved in the development of offshore oil and gas. Dealing with the problem of overflow and blowout in deepwater drilling, the most effective technical measures are based on early detection and identification of gas influx. The research on the degree of gas invasion is the basis of the formulation and implementation of well control measures. In this paper, a simulation model of gas-liquid two-phase flow after the happening of gas influx is established to calculate the cross section gas content, mud tank overflow, and bottom-hole pressure. Through the calculation, the real-time quantitative relationship between the characterization of the gas content and the bottom-hole pressure and the increment of the mud pool was established, and then the realtime quantitative degree of gas invasion is analyzed.

2021 ◽  
Author(s):  
Harpreet Kaur Dalgit Singh ◽  
Bao Ta Quoc ◽  
Benny Benny ◽  
Ching Shearn Ho

Abstract With the many challenges associated with Deepwater Drilling, Managed Pressure Drilling has proven to be a very useful tool to mitigate many hurdles. Client approached Managed Pressure Drilling technology to drill Myanmar's first MPD well on a Deepwater exploration well. The well was drilled with a Below Tension Ring-Slim Rotating Control Device (BTR-S RCD) and Automated MPD Choke System installed on semi-submersible rig, Noble Clyde Boudreaux (NCB). The paper will detail MPD objectives, application and well challenges, in conjunction with pore pressure prediction to manage the bottom hole pressure to drill to well total depth safely and efficiently. This exploration well was drilled from a water depth of 590m from a Semisubmersible rig required MPD application for its exploratory drilling due to uncertainties of drilling window which contained a sharp pressure ramp, with a history of well bore ballooning there was high potential to encounter gas in the riser. The Deepwater MPD package integrated with the rig system, offered a safer approach to overcome the challenges by enhanced influx monitoring and applying surface back pressure (SBP) to adjust bottom hole pressures as required. Additionally, modified pore pressure hunting method was incorporated to the drilling operation to allow more accurate pore pressure prediction, which was then applied to determine the required SBP in order to maintain the desired minimum overbalance while drilling ahead. The closed loop MPD circulating system allowed to divert returns from the well, through MPD flow spool into MPD distribution manifold and MPD automated choke manifold system to the shakers and rig mud gas separator (MGS). The automated MPD system allows control and adjustments of surface back pressure to control bottom hole pressure. MPD technology was applied with minimal overbalance on drilling and connections while monitoring on background gases. A refined pore pressure hunting method was introduced with manipulation of applied surface back pressure to define this exploration well pore pressure and drilling window. The applied MPD Deepwater technique proved for cost efficiency and rig days to allow two deeper casing setting depths and eliminating requirement to run contingency liners. MPD system and equipment is proving to be a requirement for Deepwater drilling for optimizing drilling efficiency. This paper will also capture detailed lesson learned from the operations as part of continuous learning for improvement on Deepwater MPD drilling.


2013 ◽  
Vol 821-822 ◽  
pp. 1414-1417
Author(s):  
Xiao Feng Sun ◽  
Jun Bo Qu ◽  
Tie Yan ◽  
Li Wang

When gas kick Occurs during drilling, because of pressure, temperature, coefficient of gas compressibility and other parameters changing continuously, gas will slip along the borehole and also accompany expansion some extent, and bottom hole differential pressure increases, resulting in the amount of invasion gas increasing continuously until blowout. The procedure of gas kick till blowout in the borehole is transient gas-liquid two-phase flow, studying on The development of gas-liquid two-phase flow parameters variation characteristics and bottom hole pressure variation characteristics plays an significant role to understand blowout occurrence and development characteristics. This paper using methane-mud as the circulating medium simulates the procedure of gas kick till blowout near the bottom under the condition which is almost the onsite drilling process, Analyzing the flow pattern, bottom hole pressure variation characteristics, and velocity distribution under the different stages of gas kick, different influx, and obtained an initial understanding.


2020 ◽  
pp. 014459872096415
Author(s):  
Jianlin Guo ◽  
Fankun Meng ◽  
Ailin Jia ◽  
Shuo Dong ◽  
Haijun Yan ◽  
...  

Influenced by the complex sedimentary environment, a well always penetrates multiple layers with different properties, which leads to the difficulty of analyzing the production behavior for each layer. Therefore, in this paper, a semi-analytical model to evaluate the production performance of each layer in a stress-sensitive multilayer carbonated gas reservoir is proposed. The flow of fluids in layers composed of matrix, fractures, and vugs can be described by triple-porosity/single permeability model, and the other layers could be characterized by single porosity media. The stress-sensitive exponents for different layers are determined by laboratory experiments and curve fitting, which are considered in pseudo-pressure and pseudo-time factor. Laplace transformation, Duhamel convolution, Stehfest inversion algorithm are used to solve the proposed model. Through the comparison with the classical solution, and the matching with real bottom-hole pressure data, the accuracy of the presented model is verified. A synthetic case which has two layers, where the first one is tight and the second one is full of fractures and vugs, is utilized to study the effects of stress-sensitive exponents, skin factors, formation radius and permeability for these two layers on production performance. The results demonstrate that the initial well production is mainly derived from high permeable layer, which causes that with the rise of formation permeability and radius, and the decrease of stress-sensitive exponents and skin factors, in the early stage, the bottom-hole pressure and the second layer production rate will increase. While the first layer contributes a lot to the total production in the later period, the well bottom-hole pressure is more influenced by the variation of formation and well condition parameters at the later stage. Compared with the second layer, the scales of formation permeability and skin factor for first layer have significant impacts on production behaviors.


2020 ◽  
Author(s):  
M. Mokliak ◽  
B. Mishchuk ◽  
A. Hrytsanchuk ◽  
M. Schepanskyi

2013 ◽  
Vol 37 ◽  
pp. 3291-3298 ◽  
Author(s):  
Mingze Liu ◽  
Bing Bai ◽  
Xiaochun Li

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