Case Studies

Some New Developments in Oil Drilling Industry Technology

1.Foreign countries have developed PDC drill bits with irregular teeth suitable for flint formations

In order to overcome the problems of short lifespan, limited footage, and low efficiency of conventional PDC drill bits in drilling flint formations (with a hardness level of 7), Dragon Oil Company and NOV collaborated to develop ϕ 215.9mm and ϕ 152.4mm irregular tooth PDC drill bits which were applied in the Gulf of Suez, achieving good results in speed increase and cost reduction.

The PDC drill bit with irregular teeth is equipped with chisel shaped cutting teeth at the cone, nose, and shoulder of the drill bit, meeting the rock breaking requirements of hard and brittle formations and significantly improving the point load during the rock breaking process; When drilling through flint formations, specific grades of cutting teeth are selected to meet the requirements of wear resistance, thermal wear, and mechanical wear;In the process of drill bit design, hydraulic parameters and the geometric shape and length of the diameter retaining palm were optimized, and spare teeth and torque control teeth were added. Among them, the spare tooth will not affect the normal operation of the front main cutting tooth. It can replace the main cutting tooth to continue working in the event of damage to the main cutting tooth, reducing the number of trips and effectively preventing the bottom of the drill bit from grinding out annular grooves;This drill bit contains two types of drill nozzles, which are optimized for position and validated for effectiveness using computational fluid dynamics.

At present, the irregular tooth PDC drill bit has undergone 12 downhole tests in Suez Bay, Egypt. One ϕ152.4mm irregular tooth PDC drill bit had a footage of 1026.87m and penetrated a conglomerate formation with a thickness of 116.13m. Compared with the same section of the adjacent well using three drill bits, the mechanical drilling speed (ROP) increased by 50% to 85% and the drilling cost decreased by 24% to 75%;Another ϕ215.9mm irregular tooth PDC drill bit had a footage of 1871.78m and penetrated a conglomerate formation with a thickness of 90.22m. Compared with the same section of adjacent wells using four drill bits, the ROP increased by 59% to 178% and the drilling cost decreased by 41% to 69%.


2.Successful on-site testing of insulated drill rods by Canada's Eavor company

Canadian company Eavor Technologies has launched an Insulated Drill Pipe (IDP) that reduces heat transfer during the transportation of drilling fluid to the Lower Hole Assembly (BHA), effectively reducing BHA temperature, reducing equipment failures, and improving drilling fluid performance. IDP is a specially designed drill pipe mainly composed of an inner pipe, an outer drill pipe, and an insulation layer. It can reduce the reverse flow heat transfer phenomenon caused by the increase in bottom hole temperature caused by the heat transfer between the drilling fluid inside the drill string and the drilling fluid in the annulus, thereby reducing the impact of temperature on drilling efficiency and equipment life. The insulation capacity of IDP usually depends on parameters such as the convective heat transfer coefficient (outer and inner surfaces) and thermal conductivity (liner and insulation material) of the drill pipe.

In 2022, Eavor successfully tested the application performance of IDP in high-temperature geothermal in the Eavor Deep project in New Mexico. The drill pipe can ensure smooth drilling operations in environments up to 399℃, even when the rated temperature of downhole equipment is usually only 149℃. In May 2023, in the geothermal research project (FORGE project) funded by the US Department of Energy, Eavor Company used IDP for two consecutive bottom hole assemblies BHA11 and BHA12 of FORGE 16B (78) -32 well. BHA11 used insulated drill rods, while BHA12 used approximately 70% insulated drill rods, and BHA10 and BHA13 used conventional drill rods. The experimental results show that using all IDP drill rods can reduce BHA temperature by 26-41℃, while using some IDP drill rods can reduce BHA temperature by 16.67-30.56℃, confirming that IDP drill rods can effectively control bottomhole temperature in high-temperature environments.


3.Nabors pioneered a closed-loop drilling automation solution based on artificial intelligence

In 2023, Nabors, in collaboration with software development company Corva based in Houston, pioneered a closed-loop drilling automation solution for the drilling industry. It uses an artificial intelligence based mechanical drilling rate (ROP) optimizer for drilling prediction, combined with the SmartROS drilling rig operating system, to remotely control the automatic driller at the drilling site through seamless cloud to cloud connection without the need for any additional drilling equipment. This technology has been applied in the Williston Basin, resulting in a 61% increase in mechanical drilling speed (ROP) and a 1.5 day reduction in drilling time.

This scheme utilizes machine learning to analyze historical data from adjacent wells to determine the optimal set point, reducing equipment wear and impact vibration; By using dynamic changes in drilling depth data to monitor actual drilling costs, adjacent wells and drilling rigs can be added to display the current drilling depth and dynamic costs in real-time; Visualize drilling parameters through screen tracking technology, including daily feet, cost per foot, and other indicators; By utilizing closed-loop automation, each well can reduce 5000 human-machine interface (HMI) interactions. This plan also comes with intelligent drilling automation products, RigCLOUD edge infrastructure, Corva applications, etc., enabling on-site and remote teams to interact, analyze, and collaborate in new ways.

This technology has been applied in 6 wells in the Williston Basin, optimizing drilling pressure, rotation speed, and pressure difference within the mechanical drilling speed target range set by the client, analyzing drilling parameters in real-time, and recommending the optimal parameters based on thresholds. By integrating with SmartROS, the optimized plan is automatically executed to achieve continuous optimization control. The application effect found that the average mechanical drilling speed of 6 wells increased by 61%, and the lifespan of the drill bit was extended.


4.Successful ground simulation test of Saudi Aramco high-power laser system

Recently, a high-power laser system developed by Saudi Aramco for drilling, perforation, and descaling has undergone ground simulation tests and has been successful.

The system consists of a laser energy generator, a nitrogen tank, a vacuum truck, and downhole tools. Generate a laser beam (energy) on the ground through a laser source, transmit it to downhole tools using fiber optic cables, and then use downhole tools to control the geometric shape of the beam. At present, the underground laser head has been upgraded from the first and second generation gas blowing media to the third generation tool that utilizes gas and liquid blowing. Allow the beam to be coaxial with the fluid, resulting in complete internal reflection, suitable for both vertical and horizontal wells.

To verify the reliability of the laser system, a biaxial loading frame was used to provide a stress of up to 140 MPa (20000 psi) and heated to 100 ℃ for downhole condition simulation. The test results show that when the rock is in a stress state, the laser beam will interact with the underground environment after leaving the laser head. The fluid, rock debris, and other debris in the underground environment will hinder the interaction between the laser beam and the rock. By using a fluid with higher refractive index (compared to the underground fluid), low light absorption (at the wavelength of the laser beam), high thermal capacity, controllable density, chemical stability, non volatility, and high flash point as the laser beam (transmission), blowing (clearing debris), and controlling the propagation of pressure (good balance), the interaction between the laser and the rock can be effectively improved. The success of this large-scale simulation experiment confirms that high-power laser technology may be a reliable, adaptable, and future oriented universal solution in the future.


5.Baker Hughes X-treme Windowmaster Oblique Drilling System

Baker Hughes' X-treme™ Windowmaster™ oblique drilling system provides faster and more efficient side drilling, which can mill a window in one run. Compared with traditional methods, the lateral drilling speed of the X-treme™ Windowmaster™

 system has been increased by three times, reducing drilling time by 50%, and also eliminating specialized cleaning operations. Its advantages mainly include:

(1) Significantly reduced the use of pipe threads. This inclinometer can be set at any depth, whether it is hydraulic or annular, without the need for additional tools, drilling, or using a backup system.

(2) Significantly reduced drilling time. Place the slanting device in the casing, with a greater depth and the ability to push and pull; Working under restricted conditions, the drilling speed is almost unrestricted, and there is no need for prior cleaning operations; When encountering confined spaces such as large ovality or deformation of the casing, deeper exit points and shorter horizontal sections can be obtained.

(3) Eliminated the red risk during the assembly process. This diagonal cutter has improved its handling and operation methods. Through design, it only requires a standard drill pipe connection to match the milling cutter and connector, saving up to 3 hours per operation.


X-treme™ Windowmaster™ system can grind out perfect rat hole windows, so there is no need for additional drilling to expand or polish the casing outlet window. Baker Hughes combines proprietary advanced milling technology with PathMaker™ polycrystalline diamond cutting teeth to design a hybrid drill bit milling cutter that can be applied to any rock type or casing grade.

X-treme™ Windowmaster™ system can collect downhole data in conjunction with Baker Hughes' xSight™ casing outlet analysis service, assisting operators in pre operation planning and post operation analysis. At the same time, the inclinometer system can provide real-time downhole data, optimize grinding and milling parameters, and confirm the load by monitoring the dense parts of the wellbore, in order to understand when the bottom drilling tool combination of grinding and milling will detach from the inclined surface of the inclinometer. The system uses dedicated connectors instead of traditional bolts, eliminating operational limitations such as low tripping speed, soft start and stop, rotation issues, and weight limitations, thereby avoiding faults and pipe breakage caused by related operations.

The design of the system is very robust, with few moving parts and includes built-in redundant mechanical activation devices. The anchor can be set in any direction, or it can be unset and redirected or reset after initial activation. A disposable scraper can also be installed to scrape specific areas. Once the desired depth is reached, seal the well and apply pressure to the annulus to activate the anchor. The anchor is fully seated by applying pressure and rotating the shear milling component to disconnect from the connector.

X-treme™ Windowmaster™ oblique drilling system has been applied on site in the offshore waters of Norway, with an average tripping speed 1.6 times that of conventional systems; Compared to the fastest milling operation before, it saved 3 hours; The milling window should be completed within 6.25 hours, with a target of less than 10 hours; Compared with conventional oblique cutting systems, the milling effect is better.


6.China has developed a micro crosslinked hydrophobic binding dual skeleton high temperature resistant and high salinity drilling fluid viscosity enhancer DASL

In response to the impact of high temperature and high salinity environments on the performance of water-based drilling fluids in deep and ultra deep layers, China University of Petroleum (East China) has developed a water-based drilling fluid viscosity enhancer DASL with a micro crosslinked hydrophobic binding dual skeleton, which has good viscosity increasing effect under high temperature and high salinity conditions. The DASL thickener uses N, N-Dimethylmethylmethacrylamide (DMAA), 2-acrylamido-2-methylpropanesulfonic acid (AMPS), sodium styrene sulfonate (SSS), and lauryl methacrylate (LMA) as monomers, with triethylamine as the crosslinking agent and ammonium persulfate as the initiator, to react under certain conditions to obtain the target product DASL.

The hydrophobic binding structure and micro crosslinking structure of DASL have a good thickening effect on water; The DASL molecular chain contains a large number of amide groups as adsorption groups, which can adsorb on the surface of clay particles to increase flow resistance; DASL molecular chains bridge multiple clay particles, causing them to overlap and form a network structure, significantly increasing the structural viscosity of drilling fluid. Under salt containing conditions, salt can promote the intermolecular association of hydrophobic groups on the DASL molecular chain, increase the internal network structure of drilling fluid, and maintain viscosity. Under high temperature conditions, DASL molecular chains contain rigid benzene rings, and the main chain is a carbon carbon bond with high bond energy, which is not easily broken. The micro crosslinking structure also improves thermal stability, making it less prone to decomposition at high temperatures. Therefore, DASL can still significantly improve the viscosity of drilling fluid under high temperature and high salt conditions.

Using 4% bentonite slurry as the base slurry, the effects of aging for 16 hours on the viscosity, dynamic shear force, API filtration rate, and HTHP filtration rate of drilling fluid were tested. After aging at 210℃, the apparent viscosity (AV) of drilling fluid with 1% DASL addition is 23.5 mPa·s, and the API filtration loss is 9.2 mL. It has a good viscosity increasing effect. Add 2% DASL to the base slurry and then add different contents of NaCl to prepare saline drilling fluid. After aging at 200 ℃, with the increase of NaCl content, the highest AV value of 31mPa·s is reached at 20% NaCl content, and the lowest API filtration rate is 5.2mL.