Fundamentals of Drilling Engineering

At the first week we were listen the lecture, which calls “Fundamentals of Drilling Engineering”. Moreover, we were familiarized with some interesting data.

There are exist different well phases such as Seismic, Drilling, Completion, Production, Intervention, P & A (Plug the well).

A well drilled with the purpose of discovering a new petroleum reservoir is called an exploration(or wildcat) well. Wildcat wells are the very first ones drilled in a certain unexplored area. After a wildcat well has shown the potential of a reservoir to be productive, appraisal wells may be drilled to obtain more information about the reservoir and its extension. Once a newly discovered reservoir is considered economically viable, a development plan is established and development / productionwells are drilled to produce the oil and gas present in the reservoir. Besides the most common exploration and development wells, special wells may be drilled for a variety of purposes including stratigraphic tests and blowout relief.

We also were acquainted with the term “rotary system’ and their parts. The main parts of the rotary system with a rotary table are the swivel, kelly, and drill string.

Modern rigs use a top drive to replace the kelly, kelly bushings and rotary table. There are several types of drilling rigs such as Jack-up, drillship, semi-submersible etc. Depending on the formation type, hardness and abbrasiveness – a proper bit has to be selected to optimize ROP: Roller cone, Fixed cutter bits – PDC (polydiamond crystalline), Diamond bit, Drill out bicenter bits – Hole enlargements, Coring bits (take sealed samples of formation to surface), Milling tools (special bits are required for making hole in a steel casing when performing a sidetrack), Hybrid bits (Recent technology).

The main difference between roller cone and PDC bits is that first one is used for soft formations while the second one from soft to medium hard formations.

The more cutters that are placed on the shoulder towards to gauge, the more aggressive the bit will be and can more easily build angle.

The main advantages of using directional drilling: avoid salt dome structures; drilling through salt can cause large washouts, lost circulation and corrosion, faults formation, drilling of many wells from one platform, fractured formations (e.g carbonates) have vertical fractures.

Where to set the casings? It depends on strength of casing (collapse, burst, tension), need for isolating unstable formations, well pressure/avoid losses, avoid leakages to surface, casing has to be set and cemented in a tight formation i.e preferable shale, not sand.

Three major problems that can occur during a drilling operation: kick (Inflow of gas/oil in the well during operation, If not controlled, it can lead to a blowout), lost Circulation (Mud losses to formation, can lead to a kick), stuck pipe (If the drillstring is stuck, the worst-case scenario might be to plug).

During normal productions, we need two barriers: Downhole safety valve (first barrier), Annular safety valve (first barrier), XMT (Christmas tree).

During the production phase, there can be several reasons for performing a well intervention operation: Scale/hydrate/wax/asphaltene removal, Azid stimulation (carbonates), Removing sand/cleaning sand screens, Perform production logging to detect water-producing formations that should be sealed.

Different methods/equipment for intervention in live wells: Pumps, Wireline (scale milling, mechanical jobs, shooting new perforations, to detect which layer is producing water?), Coiled tubing (Azid stimulation (carbonates), Sand cleanouts (e.g long horisontal wells with sand)/sandscreens), Snubbing, Rig (e.g. rig assisted snubbing).

 

Introduction to Enhanced Oil Recovery

Another useful information was represented by Nussipkozhayev Aibol. He explained us information about Introduction to Enhanced Oil Recovery, Global oil demand and Oil and gas market ripe for breakthrough enhanced oil recovery solution:

· World oil consumption rate at 96.8 million barrels per day

· 1/3 production increase over next 15 years to meet projected demands

· Market stability requires $85B annual investment to 2025

· Oil produced faster, less expensive and with less disturbance to environment from existing wells

· EOR can prolong life of oil fields up to 30 years when employed on “proven” reserves

Let's consider some actual facts:

Nearly two-thirds of the world’s energy comes from oil and natural gas.

· Oil and natural gas account for “virtually all transportation fuel in the civilized world.

· The world has taken the availability of oil and natural gas for granted, and expects them to be affordable.

Exploration and production

Despite the enormous profits being realized by the “major oil companies”, and an estimated $150 billion spent on oil exploration and development in 2009, most of the money went to: Production from known reserves rather that seeking new ones!

Recovery mechanisms

Enhanced Oil Recovery (EOR) is:

· Oil recovery by injection of fluids not normally present in reservoir

· Excludes pressure maintenance or waterflooding

· Not necessarily tertiary recovery

Improved Oil Recovery (IOR) is:

· EOR plus additional technologies dealing with drilling, production, operations, and reservoir characterization

· An attempt to avoid negative connotation of EOR

EOR classification

Thermal EOR (Steam flooding):

· The thermal processes (steam injection) have the greatest certainty of success and potential applications in about 70% of enhanced oil recovery worldwide.

· Thermal methods also provide the highest recoveries at the lowest costs

Thermal EOR (In-situ combustion):

· Old technology (1960's)

· High Recovery Factor:

· up to 60% •Self-generation of energy (coke consumption)

· In situ upgrading (thermal cracking)