Numerical Study of a Flow Field Near the Bit for a Coiled-Tubing Partial Underbalanced Drilling Method

2019 ◽  
Vol 141 (10) ◽  
Author(s):  
Huaizhong Shi ◽  
Hengyu Song ◽  
Heqian Zhao ◽  
Zhenliang Chen
Keyword(s):  
Flow Field ◽  
Drilling Fluid ◽  
New Method ◽  
Circulation System ◽  
Borehole Stability ◽  
Pressure System ◽  
Coiled Tubing ◽  
Underbalanced Drilling ◽  
Wellbore Pressure ◽  
Drilling Method

A new drilling method called coiled-tubing partial underbalanced drilling (CT-PUBD) was proposed in this paper. The method is not only able to enhance rate of penetration (ROP) just like the conventional underbalanced drilling technology but can also maintain borehole stability in the upper formation. In the new method, the wellbore pressure system is divided into two parts by a packer: (1) normal pressure system in the upper formation used to balance formation pressure and maintain borehole stability and (2) an underbalanced pressure system in the annulus near the bit used to enhance ROP. Because the pressure system and the circulation system are different, the cuttings transportation process of the method is different from the conventional way. Therefore, it is essential to study how to carry cuttings away efficiently. The flow field and cuttings distribution in the annulus near the bit were analyzed by computational fluid dynamic (CFD) methods. Cuttings transportation trajectory, velocity distribution, and cuttings concentration distribution were obtained under different holes’ parameters of the backflow device (including holes number, diameter, distance, and angle) and different drilling fluid viscosities. The results show that these parameters all have influence on cuttings carrying efficiency, and the most influential parameters are viscosity, angle, and diameter. According to the result of an orthogonal test, a suitable combination of the holes’ parameters was obtained. In the combination, the value of holes number, diameter, distance, and angle is 4, 50 mm, 300 mm, and 120 deg, respectively. This paper provides a theoretical basis for an optimization design of the new method.

Case Study of Underbalance Coiled Tubing Drilling to Increase Well Productivity and Ultimate Recovery in Tight Gas Reservoir Onshore Field, Abu Dhabi

2021 ◽  
Author(s):  
Abdelhak Ladmia ◽  
Martin Culen ◽  
Abdulla Bakheet Al Katheeri ◽  
Fahad Mustfa Al Hosani ◽  
Graham F. Edmonstone ◽  
...  
Keyword(s):  
United Arab Emirates ◽  
Drilling Fluid ◽  
Abu Dhabi ◽  
Christmas Tree ◽  
Tight Gas ◽  
Gas Reservoirs ◽  
Reservoir Performance ◽  
Coiled Tubing ◽  
Underbalanced Drilling ◽  
Tight Gas Reservoir

Abstract Coiled Tubing Drilling (CTD) has been growing and developed rapidly through the last two decades. There have been numerous highly successful applications of CTD technology in Alaska, Canada, Oman and the United Arab Emirates (Sharjah Sajaa and Dubai Murgham fields), among other places. Currently, Saudi Arabia has undertaken a campaign for the last seven years that has shown successful results in gas reservoirs. ADNOC initiated a trial Coiled Tubing Underbalanced Drilling (CTUBD) project in the onshore tight gas reservoirs in Abu Dhabi, United Arab Emirates beginning operations 1-December-2019. The initial trial will consist of three (3) wells. The purpose of the trial is to assess the suitability of CTUBD for drilling the reservoir sections of wells in these fields, and further application in others. The reason for choosing coiled tubing for drilling the reservoir sections is based upon the high H2S content of the reservoir fluids and the premise that HSE can be enhanced by using a closed drilling system rather than an open conventional system. The three wells will be newly drilled, cased and cemented down to top reservoir by a conventional rig. The rig will run the completion and Christmas tree before moving off and allowing the coiled tubing rig to move onto the well. The coiled tubing BOPs will be rigged up on top of the Christmas tree and a drilling BHA will be deployed through the completion to drill the reservoir lateral. The wells will be drilled underbalanced to aid reservoir performance and to allow hole cleaning with returns being taken up the coiled tubing / tubing annulus. The returns will be routed to a closed separation system with produced gas and condensate being primarily exported to the field plant via the production line, solids sparge to a closed tank or pit and the drilling fluid re-circulated. The primary drilling fluid will be treated water; however, nitrogen may be required for drilling future wells in the field and will be required regardless for purging gas from the surface equipment during operations. A flare will also be required for emergency use and for start-up of drilling. If the trial proves a success, a continuous drilling plan will be put in place.

Pressure Profile in Annulus: Solids Play a Significant Role

2014 ◽  
Author(s):  
Feifei Zhang ◽  
Stefan Miska ◽  
Mengjiao Yu ◽  
Evren Ozbayoglu ◽  
Nicholas Takach
Keyword(s):  
Flow Rate ◽  
Pressure Loss ◽  
Drilling Fluid ◽  
Pressure Profile ◽  
Accurate Estimation ◽  
Circulation System ◽  
Precise Knowledge ◽  
Significant Difference ◽  
Wellbore Pressure ◽  
Drilling Operations

In drilling operations, accurate estimation of pressure profile in the wellbore is essential to achieve better bottom hole pressure control. Adjusting the drilling fluid properties and optimizing flow rate require precise knowledge of the pressure profile in the circulation system. Annular pressure profile calculations must consider solids present in the drilling fluid because the solids drilled from formations may have a significant effect on pressure in the wellbore. In cases of high solids fraction or solid pack off, the pressure loss caused by solids is much higher than the friction pressure loss. This paper looks into the effect of solids on the wellbore pressure profile under different conditions. An extensive number of experiments were conducted on a 90-ft-long, 4.5″x8″ full-scale flow loop to simulate field conditions. The effects of solids on pressure profile in the annulus are investigated. In the experimental results, a significant difference is found between the pressure profile with solids and without solids in the wellbore. A practical approach to calculate the pressure profile by considering the effects of solids in the wellbore is developed. This approach is based on the results of solids behavior in the wellbore. Both solids fraction in the well and solids pack off are considered in the proposed approach. The prediction results are in good agreement with the experimental data. The results of this study show how the pressure profile in the wellbore varies when solids present in the annulus. The pressure gradient with solids can be several times larger than the pure friction loss without solids. A decrease in flow rate may lead to a higher pressure profile and the risk of solids pack off in the wellbore because it increases the solids fraction. Results of this paper may have important applications in drilling operations.

A laboratory set up for the measurement of wellbore instability due to erosion of unconsolidated formations

2015 ◽  
Vol 55 (1) ◽  
pp. 329
Author(s):  
Ghazal Avijegon ◽  
Joel Sarout
Keyword(s):  
Oil And Gas ◽  
Drilling Fluid ◽  
Ct Scanning ◽  
High Flow ◽  
Annular Space ◽  
Chemical Additives ◽  
Flow Loop ◽  
Coiled Tubing ◽  
Early Results ◽  
Set Up

Borehole instability is a recurring issue encountered during drilling operations in the oil and gas, and mining industries. In exploration drilling using coiled tubing technology, boreholes are slim and the annular space is usually tight. Similar situations are also encountered around the drill-collar section in standard drilling where the annular space can be tight; therefore, the drilling fluid has a high flow velocity and a turbulent flow regime is dominant. The flow conditions are the governing conditions for borehole erosion, which can lead to borehole instability. Erosion of the borehole introduces more cuttings into the annulus space, which is detrimental to the efficiency of cuttings transport and brings contamination to samples being retrieved at the surface for geochemistry and mineral analyses. In this peer-reviewed paper a new laboratory set-up aimed at estimating borehole erosion in pre-drilled rock samples is reported. A flow loop unit is used, which allows the injection of high flow-rates of any type of fluid composed of chemical additives and simulated cuttings. Early results of an exploratory study are reported in terms of changes in the internal borehole diameter (ID) of the sample before and after the erosion experiment. These were recorded using X-ray CT scanning. This change in ID acts as a measure of the formation’s erodibility, from which shear stress is estimated.

scholarly journals A solids-free brine drilling fluid system for coiled tubing drilling

2018 ◽  
Vol 45 (3) ◽  
pp. 529-535 ◽  
Author(s):  
Xiaojun WANG ◽  
Jing YU ◽  
Yunchao SUN ◽  
Chao YANG ◽  
Lizhou JIANG ◽  
...  
Keyword(s):  
Drilling Fluid ◽  
Fluid System ◽  
Coiled Tubing

First Use of Coagulant for Solids in the Drilling Fluid Crude Oil for Underbalanced Drilling in Russia (Russian)

2019 ◽  
Author(s):  
Vadim Nikolayevich Averkin ◽  
Andrey Valerievich Krylov ◽  
Petr Leonidovich Ryabtsev ◽  
Yury Valerievich Lukovkin
Keyword(s):  
Crude Oil ◽  
Drilling Fluid ◽  
Underbalanced Drilling

Feasibility Study of Underbalanced Drilling Using Coiled Tubing (CT-UBD): A Case Study of Field A, Indonesia

2013 ◽  
Author(s):  
Lamdamatra Arliyando ◽  
Samuel Sinaga ◽  
Gde Valdy Arimbawa ◽  
Bonar Tua Halomoan Marbun
Keyword(s):  
Feasibility Study ◽  
Coiled Tubing ◽  
Underbalanced Drilling

Feature-Section-Criterion for Predicting Lean Blowout and Comparison Research

2013 ◽  
Author(s):  
Zhibo Zhang ◽  
Hongtao Zheng ◽  
Honglei Yang ◽  
Ren Yang ◽  
Qian Liu ◽  
...  
Keyword(s):  
Experimental Data ◽  
Flow Field ◽  
New Method ◽  
Engineering Applications ◽  
Lean Blowout ◽  
Comparison Research ◽  
Annular Combustor ◽  
Combustion Flow ◽  
Feature Section

Lean blowout (LBO) plays an important role in combustor performance. A new method named Feature-Section-criterion (FSC) for predicting the LBO of annular combustor has been put forward and expounded in this paper. A CFD software FLUENT has been used to simulate the combustion flow field of an annular combustor. The process of blowout and effects of flow split among swirlers and primary holes have been researched by using of FSC. The result shows that the predictions of FSC are in agreement with corresponding experimental data. So this method for predicting lean blowout is reliable and can be used for engineering applications.

Sign in / Sign up

Export Citation Format

Share Document