cbm persentation dsign

8/6/2019 cbm persentation dsign

http://slidepdf.com/reader/full/cbm-persentation-dsign 1/21

COALBED METHANE

By :

Febriarto (113070153)

Ferry Apriadi (113070176)

Class : C

Petroleum Engineering Departement

Mineral Technology Faculty Universitas Pembangunan Nasional ³Veteran´ Yogyakarta

2011



� ABSTRACT

� INTRODUCTION

� COAL CHARACTERISTIC

� DIFFERENCES WITH CONVENTIONALRESERVOIR

� COMPARISON PRODUCTION METHOD

� CBM IN INDONESIA

� CONCLUSION

O

utline



Abstract

Coalbed methane (CBM) is an increasingly important source of the world¶s natural gasproduction with many countries, including

Indonesia, actively developing this unconventionalenergy source.



Introduction

Natural gas is a substance called methane(CH4). Coal bed methane (CBM) is found in coalseams. CBM is generated from a biological process

as a result of microbial action or from a thermalprocess. Often a coal seam is saturated with water,

with methane is held in the coal by water pressure.



Figure 1: Coalification



Coal Characteristic

Similar to conventional naturally fracturedreservoirs, coal is generally characterized asa dual-porosity system because it consists of

a matrix and a network of fractures.



Figure 2: Coal is a DualPorosity System

Figure 3: Example of Coal

Cleat Structure



Differences With Conventional Reservoir

The most significant differences are:

1. In a conventional reservoir, the majority of the gas is contained in the pore space but in aCBM reservoir, the majority of the gas isadsorbed (bonded to the coal molecules) inthe matrix.

2. In a conventional reservoir, reservoir gasexpands to the producing wells in directresponse to any production-induced pressuregradient. But CBM reservoirs generally require that reservoir pressure be below somethreshold value to initiatemgas desorption.



3. In a CBM reservoir, a gas molecule must firstdesorb and diffuse through the coal matrix toa cleat. It can then move through the cleated

fracture system and the hydraulic frac-stimulation to the wellbore via conventionalDarcy flow.

Cont«



To encourage the CBM to flow, the naturalpressure in the coal seam must be decreased by de-watering the coal. A pump located at the

wellhead removes the water that naturally occupies the cleats. This lowers the reservoirpressure along the particular coal seam, drawsthe gas out of the coal and allows it to flow intothe well bore. Effective de-watering may take

anywhere from several months to several years.

Cont«



Figure 4: CBM Development Process



Comparison Production Method

y W ell Spacing

for same large area, CBM field needs moreproduction well then coventional gas field.

Conventional Gas : 640 acres per well

CBM : 80 ± 320 acres per well



y Production Profile

During start-up operations, a conventionalnatural gas well produces large volumes of gasand very little water. O ver time, gas production

decreases while the water increases, until the gasreserve is depleted or the volume of water

becomes too great. Conversely, CBM wellsproduce large quantities of water at first and

only small amounts of gas. During the initial de- watering phase (usually several months), gasproduction increases steadily while the amountof water decreases.

Cont«



Figure 5: Generalized Production Profilefor CBM



y Infrastructure

CBM operations require gas and water-gathering systems. W ater is collected in

storage tanks at the well and transported by truck to a disposal site or moved by pipelineto a suitable central disposal site

Cont«



Coalbed Methane in Indonesia

y Indonesia has the 2nd largest CBM reserves. Totalpotential CBM reserve in Indonesia is estimated of about 453.3 TCF from 11 basins stretching out over

the regions



Figure 6: CBM in Indonesia



y The economic potency of CBM in Indonesia must be supported by well developed legal infrastructure.CBM falls into the oil and gas regulations regime

due to its nature as a gas fuel. Currently, thespecific legal basis for the exploration andexploitation of CBM is regulated by Minister of Energy and Mineral Resources No. 36 of 2008 onCBM Business Activities (CBM Regulation).

Cont«



Conclucions

1. Coalbed methane is formed during coalification.

2. CBM reservoir, the majority of the gas is adsorbed(bonded to the coal molecules) in the matrix

3. To encourage the CBM to flow, the natural pressurein the coal seam must be decreased by de-wateringthe coal.

4. During start-up operations, a conventional naturalgas well produces large volumes of gas and very little water. O ver time, gas production decreases

while the water increases, until the gas reserve isdepleted or the volume of water becomes too great.



5. Total potential CBM reserve in Indonesia isestimated of about 453.3 TCF from 11 basinsstretching out over the regions.

6.The economic potency of CBM in Indonesia must be supported by well developed legalinfrastructure.

cbm persentation dsign

Documents

Transcript of cbm persentation dsign