test-1 material - well design

8/12/2019 Test-1 Material - Well Design

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COMPLETION STRATEGIES FOR GAS TIGH

RESERVOIRS


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OBJECTIVES

To describe the completion practices being used for low permeabi

canyon sand and Marrow sand reservoirs.

To show different fracture treatment methods implemented in these re

To show the estimated economics of using such methods.

METHODOLOGY

To enable this study, data from Austin Chalk near Pearsall, Texas, Canyon Sa

Ozona, Texas, and Morrow Gas Sand of New Mexico reservoirs have been us

well completion strategies for gas tightor low permeability reservoirs.


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PROBLEM STATEMENT

Austin Chalk, Canyon sand and Marrow sand are

permeability(tight) reservoirs, whereby producing from them

an easy task. Adding to that, the formation damage is another

factor that strictly affects the drilling fluids, testing, ceme

perforation and stimulation, that is, the drilling and comp

operations. Hence, special fracture treatment and comp

methods are needed.


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PERFORATING

For Austin Chalk, jet guns are mostly used and 40-60holes(equally spaced) are done to ease the limitedentry technique of fracture treating the pay zone.Logs are also used to locate the perforating points. Big

hole burr-free guns are used for perforations.

In Marrow Sands, 7-8 tubing with sufficient ID toallow for deep penetrating and larger Diameterperforating guns to pass.

To avoid formation damage, the tubing is swabbedout of the fluids and it is then perforated with a

pressure differential into the wellbore.

Chalk is perforated in the lower section, then a bridgeplug is set above the lower zone so as to perforateand treat the upper Zone(expensive procedure),whereas in Marrow sands the hole is loaded with acidand a clean fluid across the perforation zone.

With casing carrier guns, the perforation soaks in acid

while the tubing is installed to remove cement andmud damage.

Fig.1 average daily rate vs. months an

acidized marrow well

Fig3. DSFig2. Schematic of Fractures due to injection

Fig.3 Perfo


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FRACTURE TREATING

For Austin, oil water emulsions with 2ppg ofsand as frac treating method which wasreplaced by gelled water were used in thisfield.

Acid and ball sealers are also used to open

the perforations to allow for them to acceptthe treatment.

Marrow uses very viscous KCl base waterwith 4ppg sand and CO2 as energizer;Gelled weak acid is used with 1ppg sandand CO2 for rapid fluid removal.

Whereas canyon is more into multistageballer sealers with Gelled fresh water,which are diverted into each zone through15 % HCl acid.

Edge wells of marrow sands, are fractreated due to its low porosity andpermeability thus accruing the commercialproduction.

Gel and other additives in the frmixed while pumped from plastinto the well, this would create lusmall balls of dry gel that may fracture system.

Multistage needs about 30

injection rate into each zone, inexpensive. suitable for treating Chalk.

Hydraulic Fracturing is verticallyin the chalk, thus, the natural frthin zones of porosity are conndamage(by cement and mud) isand greater productivity is achielarger well hole effect.

The Marrow wells are also naturally and with no treatmperforation.

All the operators are concerneprevention of formation damagood selection of completion anmethods are very crucial.


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CONCLUSION

A careful analysis of the properties of these reservoirs must be carrie

reduce the cost while choosing the correct completion and treatment

There are two basic methods used to fracture treat the wells in the

reservoirs under the study, which are based on the concern for prev

damage and based on the economics.

Most of the study area wells were drilled prior to the big concer

damage, and convention drilling fluid, cementing, perforating and

were used.

test-1 material - well design

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