Computer Simulation Predicts Unfavorable Mud Rate and Optimum Air Injection Rate for Aerated Mud Drilling

Guo, Boyun; Hareland, Geir; Rajtar, J.M.

doi:10.2118/26892-pa

Cited by 47 publications

(28 citation statements)

References 21 publications

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“…Experiences gained from well control indicate that bubbly flow dominates the aerated mud flow in drilling operations. It is reasonable assumption that the aerated mud flow can be treated as a homogeneos mixture of liquid, gas and solid if it is flowing in bubbly regime for the purpose of pressure calculations (Guo et al, 1996). A homogeneos gives an idea that all of those three phase flow within a same velocity, thus a calculation may be more simple.…”

Section: Bottom Hole Pressure Calculationmentioning

confidence: 99%

Aerated Underbalance Drilling Screening Assessment at “X” Geothermal Field

Dwinanto

Rachmat

2015

KEn

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Fault network is a challenging problem for geothermal drilling operations. Formation fluid contains high temperature production fluid which can reach >225 o C on high enthalpy system. The other consequences is that almost all fault network has low pressure or subnormal pressure. This low pressure results to a loss circulation problem. This low pressure can even go lower if the geothermal field has been exploited for a long period. A miss reservoir management, that do not re-inject sufficient amount of fluid, will cause the reservoir pressure go lower. Another problem in Indonesia is the conservation area which almost all high enthalpy geothermal system exist. The pay zone that is beneath the conservation area must be reached by directional drilling as a solution. High temperature fluid, low formation pressure and conservation areas are problems for geothermal drilling. To overcome these problems, underbalance drilling method has an advantage dealing with low pressure reservoir. This paper introduces a way to screen the underbalance drilling method on a certain field. This study will help the quantitative and qualitative decision whether the underbalance drilling is feasible or not. The first phase qualitative decision is based on wellbore stability, loss circulation, reservoir damage, stuck pipe incident, hard drilling and cost benefit. Then it will go to the drilling fluid decision. And at the end as a quantitative decision for constructing a feasible bottom hole pressure window area with some hole cleaning assessment. Underbalance drilling assessment will be studied on field "X" at one of Indonesia's geothermal field. The screening of "X" geothermal field comes with conclusions that it has an opportunity underbalance drilling can be implemented with vertical aerated drilling wells on spesific gas and liquid flow rates.

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Section: Bottom Hole Pressure Calculationmentioning

confidence: 99%

Aerated Underbalance Drilling Screening Assessment at “X” Geothermal Field

Dwinanto

Rachmat

2015

KEn

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“…On this basis, researchers have conducted numerous studies on multiphase flow regularity in the wellbore after natural gas invasion [2][3][4][5][6]. However, an accurate analysis of the multiphase flow regularity in the wellbore after the invasion of acid natural gas under high-temperature and high-pressure conditions and the definition of the main factors that influence multiphase flow during unbalanced drilling process are required.…”

Section: Introductionmentioning

confidence: 99%

Multiphase Flow Regularity of Wellbore in Acid Natural Gas-invading Period

Hou¹,

Yan²,

Sun³

et al. 2017

JESTR

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Currently, unbalanced drilling technique is widely applied in the exploration and development process of acid oil and gas reservoir. However, the acid natural gas that invades under high-temperature and high-pressure conditions can easily result in underground failures, such as well kick and blowout. Thus, a calculation model for the multiphase flow of a wellbore that is invaded by acid natural gas was established in this study based on the principle and method of gas-liquid two-phase flow to reveal the multiphase flow regularity inside a wellbore after the invasion of acid natural gas, considering the phase change and solubility of acid gas under high temperature and high pressure. Meanwhile, a solution for the model was provided. Finally, in the case of the H75-29-9 gas well conditions in Jilin Oilfield, China, the change rule of physical properties and the change features of parameters, such as mud pit increment and pressure drop in the bottom hole after acid natural gas (methane and hydrogen sulfide) penetrated the wellbore, were obtained through an analog calculation. Results indicate that the H 2 S solubility inside the wellbore is greater than the CH 4 solubility. Moreover, H 2 S is 135 times more soluble than CH 4 in the bottom hole. The density of acid natural gas mutates near the wellhead. High H 2 S content implies that the mutation location is near the wellhead. The density mutation location of pure H 2 S mutates 400 m away from the wellhead, whereas the density of a 50% H 2 S mutates 900 m away from the wellhead. Within the same overflow period, a high H 2 S content implies a small pressure drop value in the bottom hole, mud pit increment, and shut-in casing pressure, and small volume fractions of gaseous phases at the wellhead and in the center of the wellbore. Backpressure and the gas-invaded quantity at the wellhead have great influences on pressure in the bottom hole, that is, a great backpressure at the wellhead implies a low pressure drop in the bottom hole. Moreover, less gasinvaded flow quantity implies a small pressure drop in the bottom hole. This study provides a theoretical basis for wellbore pressure control and well-killing construction under complicated conditions.

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“…For instance: any no-flowing wells are also named static well; constant circulating flow rate denotes steady well; and transitions from pumps-on and pumps-off, while mud flow rate is being adjusted or during pipe connection corresponds to a transient well performance. To describe these cases, many steady models have been developed [1] however, the classical drilling hydraulic models utilized to manage the annular pressure profile cannot capture transient flow discontinuities; i.e. mechanistic hydraulic model.…”

Section: Introductionmentioning

confidence: 99%

“…Unfortunately, some hydraulic parameters as volumetric fractions and sound velocities of flowing phases cannot directly measured at well location; the intensive use of these kind of models needs the complete set of input data; in the future, we believe that modern and intelligent DAQ systems will support this drawback. Therefore, this research is divided in three main stages: (1) Transient hydraulics model, (2) Numerical solution, and (3) Validation with a recommended practice of the American Petroleum Institute [6]. The math model, closure relationships and initial-boundary conditions are established considering true drilling conditions and the main hydraulics mechanisms.…”

Section: Introductionmentioning

confidence: 99%

Analysis of Wellbore Drilling Hydraulics Applying a Transient Godunov Scheme Considering Variations of Injected Flow Rates

Nicolás-López¹

2017

OGCE

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Abstract:A new application of the Godunov scheme to describe dynamic oil-well behavior is presented. The numerical model is able to capture discontinuities associated with surface flow-rate variations. The finite volume method and Riemann problems are utilized for building the unsteady discrete solution. Initial and boundary conditions are related to cases of static, steady and transient well condition. Well data used in simulation are taken from true operational conditions and well mechanical configuration. The results of Godunov's modeling describe the behavior of transient pressure and transient flow rate inside drill pipe and annulus. These profiles are commonly caused by turning on, adjusting mud flow rate and turning off the rig pumps. The evaluated rig indicators are: back pressure, pumping pressure, bottomhole pressure and injected flow rate. Calculated transient profiles are physically consistent and in good agreement with published well data. Therefore, engineering contribution is the application of first-order Godunov method to evaluate the transient hydraulics whereas variations of mud flow rate; also, the analysis and interpretation of the dynamic pressure behavior travelling inside the well. The Godunov scheme has robust engineering applications for modeling the transient drilling hydraulics, e.g., managed pressure drilling, hydraulics of pipe connections, and foam cementing, as well.

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Computer Simulation Predicts Unfavorable Mud Rate and Optimum Air Injection Rate for Aerated Mud Drilling

Cited by 47 publications

References 21 publications

Aerated Underbalance Drilling Screening Assessment at “X” Geothermal Field

Aerated Underbalance Drilling Screening Assessment at “X” Geothermal Field

Multiphase Flow Regularity of Wellbore in Acid Natural Gas-invading Period

Analysis of Wellbore Drilling Hydraulics Applying a Transient Godunov Scheme Considering Variations of Injected Flow Rates

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