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Time Optimizing near the Pay Zone
Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.ORCID iD: 0000-0001-8577-1776
Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.ORCID iD: 0000-0002-1629-2920
Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.ORCID iD: 0000-0002-6790-2653
2017 (English)In: Engineering, ISSN 1947-3931, E-ISSN 1947-394X, Vol. 9, no 10, p. 848-858Article in journal (Refereed) Published
Abstract [en]

Well control techniques are used in oil and gas drilling operations to control bottom hole pressure and avoid any fluid influx from formation to the well. These techniques are highly important near the pay zone in term of time. Controlling formation fluid pressure and thereby the formations behavior in a predictable fashion will help toward more optimized environmental friendly drilling operation. Time consumed to control the formation fluid pressure will range between few hours to many days. This paper discusses hydrostatic pressure distribution and changes near the pay zone for one oil blocks in Kur- distan, in the northern part of Iraq. Obtaining homogeneous increase in some drilling fluid properties will help the engineer to better interpret sampling of the lithological columns and reduce potential hole problems and operationtime.

Place, publisher, year, edition, pages
Scientific Research Publishing, 2017. Vol. 9, no 10, p. 848-858
Keywords [en]
Fluid Pressure, Well Control, Drilling Fluid, Formation, Pay Zone
National Category
Engineering and Technology Geotechnical Engineering Geophysics
Research subject
Exploration Geophysics; Soil Mechanics
Identifiers
URN: urn:nbn:se:ltu:diva-66142DOI: 10.4236/eng.2017.910050OAI: oai:DiVA.org:ltu-66142DiVA, id: diva2:1149407
Note

Validerad;2017;Nivå 1;2017-10-19 (andbra)

Available from: 2017-10-16 Created: 2017-10-16 Last updated: 2023-09-05Bibliographically approved
In thesis
1. Parameters optimization of oil well drilling operation
Open this publication in new window or tab >>Parameters optimization of oil well drilling operation
2020 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

In the beginning of 2005, the ministry of natural resources in the Kurdistan region of Iraq divided

its territory into more than 50 oil blocks based on geological setting. These oil blocks were awarded

later to different international oil companies for oil investments based on Production Sharing

Contracts (PSCs). A new oil-exporting pipe was also established from the region to the Jaihan port

in Turkey at the Mediterranean Sea.

This study is related to the oil well drilling operations in one of these oil blocks in northern Iraq

which is referred as the Bazian oil block. Drilling operations in the nearby oil blocks (Taq Taq and

Miran) were started earlier and the drilling data of those oil blocks were used as offset data in the

drilling program of the Bazian block. High similarities were expected between these oil blocks with

respect to lithology of the formations, oil well drilling techniques, and operation problems. By 2009

over twenty oil wells were drilled in the Taq Taq oil block and it is becoming one of the most

important oil fields in the Kurdistan region. In the Miran oil block, exploration for oil and gas started

in early 2008, and three oil wells were completed and started to produce crude oil. By the end of

2009, the geological and geophysical surveys in Bazian block were finished and the drilling operation

started on October 1st the same year.

This study (Parameter Optimization in Oil Well Drilling Operation) was recommended and

sponsored by the Kurdistan Regional Governorate (KRG) aiming towards more optimized drilling

in the future in the same oil block. Parameters like weight on bit, string rotation and rate of

penetration for the future drilling operation in the Bazian oil block with more optimized values

were predicted. This study was started by collecting detailed operational data from different sources

during the operations of drilling the Bazian well Bn-1. Among many sources of data, Mud Logging

Unit (MLU) data were selected for this study, as it was the most complete data set from the surface

to the final drilled depth. This thesis contains the work of five published papers in the evaluation of

the drilling operation at different intervals for the key well. Parameters for achieving the optimal

penetration rate were predicted for the future operations.

The first paper (Evaluation of Limestone Interval in the Drilled Surface Section of Bn-1 Oil Well)

was on the evaluation of the drilling operation in the surface section from 9 m to 480 m. The highly

fractured Pila Spi formation was studied for its controllable parameters like Weight on Bit (WOB),

drill string rotation (RPM) and the used torque. High loss of circulation and environmental effects

were studied. Optimum drilling fluid, drilling technique, and drilling parameters were proposed for

the future drilling operation.

In the second paper (Kicks Controlling Techniques Efficiency in Term of Time) recorded data were

analyzed to manage the drilling operation during the critical times in terms of controlling the Bottom

Hole Pressure (BHP). Productive and none productive times were analyzed through the study of

the drilling and tripping operations. Change in the drilling technique was proposed by modifying

the drilling fluid. Drilling fluid as a first barrier to control formation pressure and well kicks were

studied for their rheological properties. During the drilling operations two techniques, circulating

techniques and non-circulating methods, were implemented to control the BHP. Both methods

have been implemented to control kicks in the Bn-1 oil well and wells in other oil blocks in the

region. The process of drilling design and casing setting points have been studied based on the

utilization of accurate values of formation pressure. Data of formation pressures were used to design

safe mud weights to overcome and prevent well kicks. The emphasis has been placed on the practical

utilization of the kicks pressure near the reservoir. The presented relationships help in better

understanding of the lithological columns and reduce possible hole problems during the kick

appearance. Optimum casing setting point of the intermediate section was proposed for future

operations.

The third paper (Time Optimizing near the Pay Zone) was on the drilling operation inside the cap

rock. Time managing was studied for surface preparation facilities, subsurface expected pressure

control time, and the best technique to control the Bottom Hole Pressure (BHP). Well controlling

techniques in oil and gas drilling operations are used to control BHP and avoid any fluid influx from

formation to the well. Time consumed to control the formation pressure will range between a few

hours to many days. This paper also discussed the hydrostatic pressure distribution and changes near

the pay zone for the Bazian (Bn-1) oil well. Increasing linearly drilling fluid properties such as density

and viscosity with time will help the engineer to better interpret sampling of the lithological columns

and reduce possible hole problems.

Paper number four (Wiper Trips Effect on Wellbore Instability Using Net Rising Velocity Methods)

was on the effect of wiper trips operations to control parameters during the operations in two drilled

shale formations, the Tanjero and Shiranish formations. Wiper trips were evaluated based on the

lifting capacity of the cutting in the drilling fluid. This paper discussed the wiper trip effects on well

instability in shale formations. The problematic shale interval sections were studied with respect to

the time spent on the wiper trip operations. Lifting efficiency and well wall instability are

continuously changing with time. Detailed drilling operation, formation heterogeneity, rheological

and filtration characteristics of the proposed polymer water-based mud were discussed. The physical

and chemical properties of the drilled formation and drilling fluid were also studied.

Wiper trips were analyzed based on recorded history in relationship with the controllable parameters.

Two calculation models have been implemented to find the net rising cutting particle velocity in

the annular. The relation between the net rising velocity and wiper trips were analyzed with support

of results from laboratory works. Strong relationships were found between the wiper trip effects and

lithology types of the penetrated shale. A modified drilling program was proposed in relationship to

the casing setting point and drilling fluid properties that make the operations more optimized.

The fifth paper (Controllable drilling parameter optimization for roller cone and polycrystalline

diamond bits) predicts optimized Rate of Penetration (ROP), WOB and the string rotation (RPM

– rotation per minute) for the entire drilled well. The most used empirical Bourgoyne and Young

model (BYM) for roller cone bits were used in the optimization process. This model describes the

effect of eight parameters in one mathematical equation. The BYM was adjusted to be applicable

for other types of drilling bits like polycrystalline diamond compacts (PDC) bits. Controllable

parameters like WOB, RPM and ROP were clustered based on changes in Bottom Hole Assembly

(BHA) and lithology before running the model.

The implemented clustering and averaging method for the collected data in short lithological

intervals were used to eliminate the effect of noisy data and to overcome the lithology homogeneity

assumption used in other previous studies. A simpler model were introduced instead to optimize the

string rotation.

Multiple regression techniques were used in each cluster to determine optimized controllable drilling

parameters. Optimized ROP, WOB, and RPM were predicted for future drilling operations. A

clear relationship was found between the formation lithology and the controllable parameters in

each cluster.

Place, publisher, year, edition, pages
Luleå: Luleå University of Technology, 2020
Series
Doctoral thesis / Luleå University of Technology 1 jan 1997 → …, ISSN 1402-1544
Keywords
Bazian Block, Kurdistan, Iraq, Optimization, Drilling Parameters, Rate of Penetration, Wiper trips, Kicks, Pay zone, Bourgoyne and Young model
National Category
Geophysics
Research subject
Exploration Geophysics
Identifiers
urn:nbn:se:ltu:diva-73878 (URN)978-91-7790-392-5 (ISBN)978-91-7790-393-2 (ISBN)
Public defence
2020-03-31, F632, 10:00 (English)
Opponent
Supervisors
Available from: 2019-05-08 Created: 2019-05-08 Last updated: 2023-09-05Bibliographically approved

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Darwesh, Ali K.Rasmussen, Thorkild MaackAl-Ansari, Nadhir

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