JavaScript isn't enabled in your browser, so this file can't be opened. Enable and reload.

1 of 33

Well completion and production strategy
Module 5a

2 of 33

Well completion

Agenda: Well completion methods Formation evaluation Well testing Well stimulation Primary, secondary, and tertiary recovery mechanisms Unconventional oil and gas

3 of 33

Well completion methods

Completion strategy: Completion fluids Completion method Cased hole: allows better well control & workover results Open hole: cheaper, less damaging (suitable for hard rocks) Gravel pack: used for unconsolidated rocks to reduce sand production problems

4 of 33

Completion methods

Cased hole: allows better well control & workover results

5 of 33

Cementing the casing

Cementing a casing ensures proper hydraulic insolation behind the casing, preventing leaks to surface or freshwater aquifers. Casing accessories used for cementing include: Guide shoe, to guide the casing when running in and clear any restrictions or ledges in the open hole. Centralizers, to keep the casing in the centre of the hole. Scratchers, to remove the mud cake and improve bonding of the casing into the hole wall. Float shoe (collars), is a one-way valve allowing cement to flow out of the drill pipe up into the annulus and not flow back.

6 of 33

Casing accessories

Scratchers

Centralizers

7 of 33

Cementing operation/accessories

	Bottom rubber wiper (red), to wipe the mud out of the drill pipe, it has a diaphragm that will break under pressure. The top wiper plug (black) is used the displace the cement into the annulus, it is pushed down using the drill mud.

8 of 33

Cement Bond Log (CBL)

9 of 33

Completion methods

2. Open hole: cheaper, less damaging�(for hard rocks)

Tubing

Packer

Casing Cement

Open Hole

Reservoir

10 of 33

Completion methods

3. Gravel pack completion: for unconsolidated formations to reduce sand production problems

11 of 33

Formation/well evaluation

Agenda: Mud logging Coring Full core diameter Sidewall coring Open hole log Well testing Wireline testing Well testing

12 of 33

Drill cuttings

	Mud logging is the process whereby the mud and its contents emerging from the well are sampled and analyzed to obtain key information: Detect oil and/or gas shows in mud Gas samples from the degasser and delivered to gas chromatograph Rate of penetration (ROP) Collect drill cutting and catalogue description Mud logging is done on exploration and key development wells (expensive)

13 of 33

Mud logging

Mud logging equipment

Drill cuttings

Drill cuttings at the shaker

14 of 33

Typical mud log chart

15 of 33

Core sampling

Planning for coring: Cutting a core sample is desirable for exploration wells Drill cutting can give indication of zones to cored, using mud logging information (ROP, gas detection, etc.) Geological prognosis, from offset wells Type of coring technique, based on the required data to be collected (oriented core, pressurized core, preserved core)

16 of 33

How is core cut?

	Succession of jams or filled barrels will first release inner sleeve, then second sleeve, then signal that fixed core barrel is jammed or full.

Coring bit

17 of 33

Open hole logging equipment

	The purpose of open hole logs is to evaluate the formation rock and fluid properties to determine the potential of oil and gas commercial production; including: Pay thickness Formation porosity Fluid contents and saturation Lithology description (type of rocks and mineral contents)

18 of 33

Well testing

19 of 33

Well test equipment diagram

	Production data: Produced fluids are measured at surface (orifice meter) Pressure data: Surface & BH data is collected using pressure recorders Fluid samples: Samples are collected at the surface separator

20 of 33

Gas flaring and the environment

	Although gas flaring is undesirable, it is frequent in many operations; well testing, sour gas production, and for limited gas production in oil fields.

21 of 33

Wireline operation

22 of 33

Well test objectives

Well: Well deliverability: AOF, IPR Formation parameters: reservoir pressure, formation, permeability Wellbore condition: skin factor, evaluate the effectiveness of fracture or acid treatments Fluid samples: obtain surface or BH samples for various fluid studies (PVT, retrograde-condensate). Effective length for horizontal wells Regulatory compliance: including annual surveys and EOR projects

23 of 33

Well test objectives

Reservoir: Define reservoir model, composite, multi-layer, and channel, which could assist in preparing the depletion strategy Reservoir boundaries/shape, will assist in planning step out/delineation drilling programs Reservoir size, to determine the commerciality of the reservoir Strength of aquifer to determine whether water injection is required for pressure maintenance

24 of 33

Field development

The well: Well type: vertical, deviated, and horizontal Completion strategy: cased, open hole, gravel pack, and artificial lift Perforating: techniques, and multi-zone Well stimulation: acidizing and hydraulic fracturing The reservoir: Well spacing (reservoir/fluid quality, EOR) Primary production (recovery factors, off-take-rates and draw-down) Secondary and tertiary schemes

25 of 33

Timeline for full-scale development plan

26 of 33

Primary, secondary, and tertiary recovery mechanisms

27 of 33

Oil recovery mechanisms

28 of 33

Secondary and tertiary recovery schemes

29 of 33

Diagram of typical E.O.R. scheme
Where does the water come from?

30 of 33

Waterflood

Why is waterflood the most popular EOR Scheme? Water is the cheapest flooding agent for EOR The need to dispose of produced water Easy and safe to inject Proven technology

31 of 33

Oil recovery mechanism
ASP process
Alkali Alters rock wettability Alters rock chemistry, reducing adsorption Surfactant Reduces oil-water interfacial tension Polymer Improves mobility ratio Improves vertical and horizontal sweep efficiencies

32 of 33

Interfacial tension (IFT)

	Oil droplet cannot reshape, and is trapped as SOR Oil droplet can reshape and is mobilized

1

2

33 of 33

Thank you
UNEP-Norway Partnership
United Nations Avenue, Gigiri PO Box 30552 – 00100 GPO Nairobi, Kenya	www.unep.org