Fluidic Oscillation With Acid Stimulation Improves Gas-Well Productivity

Abstract

This article, written by Technology Editor Dennis Denney, contains highlights of paper IPTC 11452, "Fluidic- Oscillation Technique in Conjunction With Acid Stimulation Improves Gas- Well Productivity," by Ahmed Hegazy, Belayim Petroleum Company, and Bruce Conrad, Arshad Waheed, and Osama Sanad, Halliburton, prepared for the 2007 International Petroleum Technology Conference, Dubai, 4–6 December. The paper has not been peer reviewed. Copyright 2007 International Petroleum Technology Conference. Reproduced by permission. Low productivity of gas wells in the offshore Mediterranean Sea operations of Egypt often is caused by near-wellbore formation damage. The stimulation technique will vary depending on the type of damage; however, prevalent techniques are hydraulic fracturing and matrix acid stimulation. A new technique called "fluidic oscillation" was proposed, which would be especially applicable in cases having uncertainties regarding rock mineralogy. Fluidic oscillation is a mechanical, nonfluid-invasive stimulation technique (i.e., it is not essential to inject the treatment fluid into the reservoir to break down damage, although its use in that manner is not precluded). This technique was successful in stimulating gas wells in Egypt. Introduction The main challenge after completing two high-rate gas wells was less-than-expected production. These wells are approximately 37 miles off the Mediterranean Sea coast in the PetroTemsah field, northwest of Port Said in Egypt. This field produces gas and condensate with a condensate/gas ratio (CGR) of 60 bbl/MMscf. The producing formation is the Sidi Salem formation of Serrvallian age (Miocene), with an average porosity of 22%, average water saturation of 30%, and an average permeability of 100 md. This formation consists of four main reservoir layers (Lobe-0, -1, -2, and -3) and is at a depth of approximately 14,000 ft with a bottomhole temperature of 230°F. The bottomhole pressure ranges from 7,400 to 8,000 psi. A complete mineralogical breakdown of the rock by weight is not available, but essentially the rock is clean sandstone (80% quartz with 3 to 4% calcium carbonate and 10 to 15% feldspars and clay). The Sidi Salem formation is unconsolidated, and without adequate sand control, the wells tend to sand up, ceasing all flow from the reservoirs. The sand-control techniques used for the field include openhole gravel packs, expandable sand screens, and cased-hole gravel packs. The first example is an openhole completion with an expandable sand screen set across the zones of interest. The second well has an inside-casing gravel-pack completion.