State-of-the-Art Summary

Polymer-gel treatment for water shut-off was one of the technologies discussed. There is a science to success with water shut-off treatments. Those science insights, delivered by two individuals well respected in the field (Randy Seright of the Petroleum Recovery Research Center at New Mexico Tech and Bob Sydansk, retired Marathon and involved in developing the popular MARCIT^TM technology) in a 2004 PTTC workshop in Houston, have been captured online (www.pttc.org/
solutions/sol_2004/536.htm). Water shut-off treatments have been quite successful in the Kansas Arbuckle. KU's Tertiary Oil Recovery Project Group has developed a website where individual well treatment results are accessible (www.kgs.ku.edu/
Magellan/Polymer/index.html).

Dwyann Dalrymple, Halliburton, described their new WaterWeb^TM product (www.halliburton.com/
news/archive/2004/hesnws_
050304a.jsp), one of several relative permeability modifiers (RPMs) available from the service companies. WaterWeb's unique polymer chemistry impedes water at the source, enhancing hydrocarbon flow. It works by adsorbing onto the rock surface, reducing permeability to water seven to ten times more than it does to hydrocarbons. Field experience showed success at reducing produced water ranging from 50% to 80%, the key being to use the screening criteria to determine if the reservoir is a good candidate. Rick Flattern's article on RPMs ("RPMs and the Holy Grail," Offshore Engineer, December 2003 excerpted in PTTC's 4th Qtr 2003 newsletter available online at www.
pttc.org/news/4qtr2003/v9n4p5.
htm#1) describes RPMs more fully.

Downhole oil-water separation is one option for managing excessive water production. Through the years, industry has developed and tested various techniques to do this. In a 2004 "White Paper" for DOE, John Veil with Argonne National Laboratory summarized industry field experience (59 DOWS trials, 62 DGWS trials) with downhole oil-water separation.

Excerpted in PTTC's newsletter (www.pttc.org/news/4qtr2004/
v10n4p3.htm#2), Veil indicates that, as of that point in time, risk and cost considerations had chilled industry's interest. In the Conference, Gordon Graves with Well Completion

Stimulation
Stimulation, whether for existing or new wells, is on every operator's hot list. Stimulation is one of the most effective means of prolonging and maximizing production from mature wells. In the Oct-Dec time frame alone (see page 2, Meeting Alerts), SPE is conducting three Advanced Technology Workshops related to tight gas completion/ stimulation. One reason operators are paying more attention to stimulation is that recent work shows hydraulic fractures are much more complex than we think and we don't always know where they go. In a DOE-supported project, Pinnacle Technologies, Inc. presents several examples (presentations from day-long workshop online at www.
energyconnect.com/pttc/archive/
doe_deepgas.htm). With a lot of attention and potential, there are many new products/approaches under development. Three examples discussed during the conference follow.

Propellant Stimulation - Courtesy Mark Brinsden, Expro Group

Propellant Stimulation. In India, Expro Group has been involved in a field test of propellant stimulation. The propellant stimulation combines fuel and oxidizer. The rapid burn

releases energy in the form of a hot high pressure gas (CO2), which mixes with the wellbore fluids to form a froth. This froth enters the perforations, breaks down the rock and pushes fractures into the formation. The Neelam Heera field in offshore Mumbai, operated by ONGC, had been experiencing a relatively sharp rise in the water:oil ratio (WOR). After reviewing the production data and potential treatments the propellant stimulation was determined to potentially be the most effective. Mark Brinsden with Expro noted that seven wells were initially identified as candidates. Based on production and stimulation models, the candidate list was pared down further and additional downhole data were obtained. Two wells were treated. In the first the skin was reduced from +7 to +4.5 with a 41 BOPD increase and slightly better water-oil ratio. In the second well, the skin improved from +8 to +7 and oil production increased 244 Barrels/day.

CO2 Preflushing When Acidizing. With acid treatments, John Gidley, Consultant, contends that the precipitate of silica that occurs with an acid job reacts with oil and forms emulsions and sludges that damage the reservoir. To prevent the contact of oil and acid, he recommends a pre-flush of CO2. Licensed to Halliburton, BJ Services, and Schlumberger, CO2 pre-flushing has been applied on 103 wells, primarily Gulf of Mexico sandstones, since becoming commercially available and only two have been considered failures. In his presentation Gidley cited three examples illustrating the dramatic production increases that are achievable. In comparing conventional acid treatments on wells with similar skin, from +165 to +170 to the CO2-acidizing treatment, the conventionally treated wells skin improved to +50 to +112, while the CO2 treated well improved to +5. Oil production improved six-fold versus doubling in the conventionally treated wells. Further results can be seen at www.gidley.com.