Dynamical Simulation of High-Pressure Gas Kick in Ultra-Deepwater Riserless Drilling

Abstract During riserless drilling for ultra-deepwater gas wells, well control challenges induced by high-pressure gas kick will be faced. A two-phase flow model with consideration of high-pressure gas invasion during riserless drilling was proposed, and the model was proved to be more accurate for predicting high-pressure gas kick during riserless drilling by reproducing field data and comparison with published models. Then, a dynamical simulation of high-pressure gas kick in ultra-deepwater riserless drilling was presented. Results showed that during ultra-deepwater riserless drilling, the bottom hole pressure will be underestimated, while pit gain will be over-estimated without considering the gas acceleration effect. With the consideration of gas acceleration effect at high-pressure well bottom, the gas influx rate increases rapidly with the kick time and tends to be stable after a period of time as negative pressure difference at well bottom increases. During riserless drilling, according to the timeliness and effectivity of kick detection methods, pit gain is prior for kick detection, following bottom hole pressure, standpipe pressure, and return rate. Moreover, if early gas kick was not detected, the rapid increase in change rate of standpipe pressure and return rate can be regarded as an indicator, showing that gas is reaching mud line. Besides, the effects of shutoff time, drilling displacement, drilling fluid density increases, geothermal gradient, and reservoir permeability on kick indicators and wellbore pressure have been discussed. The research results could provide important theoretical bases and technical guidance for well control aspects of riserless drilling.

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Numerical Simulation for Gas-Liquid Two-Phase Flow along the Borehole after Air Cutting

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.821-822.1414 ◽

2013 ◽

Vol 821-822 ◽

pp. 1414-1417

Author(s):

Xiao Feng Sun ◽

Jun Bo Qu ◽

Tie Yan ◽

Li Wang

Keyword(s):

Two Phase Flow ◽

Pressure Variation ◽

Drilling Process ◽

Phase Flow ◽

Two Phase ◽

Hole Pressure ◽

Bottom Hole Pressure ◽

Bottom Hole ◽

Gas Kick ◽

Variation Characteristics

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.

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Well Control Technology of High Temperature and High Pressure with Different Well Shapes

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.316-317.860 ◽

2013 ◽

Vol 316-317 ◽

pp. 860-866

Author(s):

Yan Jun Li ◽

Xiang Nan He ◽

Xiao Wei Feng ◽

Ya Qi Zhang ◽

Ling Wu ◽

...

Keyword(s):

High Pressure ◽

High Temperature ◽

Drilling Fluid ◽

Control Process ◽

Formation Pressure ◽

Well Drilling ◽

Well Control ◽

Direct Invasion ◽

Bottom Hole ◽

Gas Kick

Well control safe is the prerequisite of safety drilling, especially for high temperature and high pressure horizontal wells. However, there are few papers about well control of horizontal well drilling, which mostly learn from vertical well control process. By means of analysis of the theory of gas kick, we conclude that underbalance, the bottom hole pressure is less than the formation pressure is the main means of gas invasion. During balance period, the gas also intrudes into wellbore through the way of direct invasion, diffusion invasion and replacement invasion, but the amount of gas kick is less, so the risk of well control is small. This paper also anlyses the kick tolerance, the kick tolerance decreases with the increasing of drilling fluid density when the formation pressure and drilling equipment is constant.

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Precise Bottom Hole Pressure Management to Reach Target Depth in a Narrow Windowed Ultra HP-HT Well: A Case for Automated Managed Pressure Drilling

10.2523/iptc-21410-ms ◽

2021 ◽

Author(s):

Ali Khalid ◽

Qasim Ashraf ◽

Khurram Luqman ◽

Ayoub Hadj Moussa ◽

Agha Ghulam Nabi ◽

...

Keyword(s):

Oil And Gas ◽

Formation Pressure ◽

Hole Pressure ◽

Bottom Hole Pressure ◽

Area Of Interest ◽

Bottom Hole ◽

Coastal Belt ◽

Managed Pressure Drilling ◽

Wellbore Pressure ◽

Target Depth

Abstract With the energy sector in crisis the worldover, oil and gas operators continue to seek more effective and efficient methods to reach potential prospects. With sharply declining oil prices, it is imperative that operators minimize the non-productive time in the drilling of all wells. Many operators are actively seeking riskier exploration to establish a strong foothold in this volatile market. One such area of interest to operators is HPHT and beyond wells. An HPHT prospect carries a high-risk high-reward potential, therefore newer and advanced methods are being deployed to successfully drill and complete HPHT wells. The Makran Coastal belt in south western Pakistan is one such area containing a potential Ultra-HPHT prospect. Many operators had attempted to drill about 9 wells in the locality but never managed to reach target depth due to drilling operations being plagued with a large number of problems. The drilling problems included high pressure influxes, stuck pipe while controlling influxes, circulation losses with high mud weights and ECD’s, differential sticking against permeable formations, inefficient bottom hole pressure control due to mud weight reduction with high temperatures and swabbing from the formation due to having an insufficient trip margin. The operator was facing an extremely narrow drilling window in the target section. The maximum formation pressure was estimated to be around 2.29 SG while the maximum fracture pressure of the formation was estimated to be around 2.35 SG in EMW. It was abundantly clear that drilling with a conventional mud system would be impossible and impractical on all forthcoming wells. As it was of paramount importance to precisely manage the wellbore pressure profile, the operator decided to apply managed pressure drilling on a candidate well. By applying managed pressure drilling techniques the operator expected to drill the section with an underbalanced mud weight and maneuver the bottom hole pressure just above the pore pressure line and thereby avoid circulation losses, detect influxes early on and control influxes without the need of ever shutting in the well, account for mud density variations with temperatures by executing an advanced thermal hydraulics model in real time, mitigate swabbing from the formation again by maintaining a constant bottom hole pressure while tripping, and finally ascertain the downhole pressure environment by conducting dynamic formation pressure tests. The successful application of MPD enabled the operator to reach target depth for the first time in the history of the area. The paper studies the planning, design, and execution of MPD on the subject well.

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Production behavior evaluation on multilayer commingled stress-sensitive carbonate gas reservoir

Energy Exploration & Exploitation ◽

10.1177/0144598720964155 ◽

2020 ◽

pp. 014459872096415

Author(s):

Jianlin Guo ◽

Fankun Meng ◽

Ailin Jia ◽

Shuo Dong ◽

Haijun Yan ◽

...

Keyword(s):

Early Stage ◽

Sedimentary Environment ◽

Production Performance ◽

Total Production ◽

Inversion Algorithm ◽

Gas Reservoir ◽

Hole Pressure ◽

Bottom Hole Pressure ◽

Bottom Hole ◽

Production Behavior

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.

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