A new fines stabilizing method which prevents migration of clay and non-clay siliceous fines, and controls formation dissolution during sandstone acidizing, has been developed.The method employs an organosilane compound which can be added directly to acid mixtures, such as hydrochloric (HCl) and hydrochloric-hydrofluoric (HCl-HF) acid. The organosilane additive reacts in situ to stabilize potentially mobile siliceous fines, and as an additive to HCl-HF acid mixtures, reduces the potentially damaging effects of excessive mineral dissolution by HF. This paper describes the use of and the mechanism by which the organosilane acid additive stabilizes fines, and reduces dissolution of sandstone by HF acid.Results of laboratory core flow tests which show the beneficial effects of employing both a proper HF acid concentration and the organosilane finesfixing agent are presented. Results of a field test are also presented.

The attached document was completed under the direction of the Environmental Sciences Section, Geotechnical Group of the Savannah River Technology Center, Westinghouse Savannah River Company. I have reviewed the document, and to the best of my knowledge, it is true, accurate, and correct.

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Recent technological advances are driving casing and liner drilling from a niche market into the mainstream environment. Improved connections, tubulars, advances in rig technology and pipe handling have enabled operators to consider drilling with casing/liner as an option on many new wells 1,2 . Escalating deepwater costs and the need to further reduce onshore drilling expenses in low cost fields continue to push the technology forward.In a mature South Texas field, an operator discovered the difficulties of drilling into formations with weak matrix strengths, loss circulation zones, and tight pore pressure/fracture gradient windows.These issues have deemed the field sensitive to aggressive drilling techniques and the operator has been forced into a conservative drilling program with reduced flow rates and lower weight-on-bit capacity. The operator needed to reduce trouble time, lower costs and make the wells more economically feasible.A service company introduced a new liner drilling system solution to get through the extensive problematic zones. The system is engineered so the operator can ream to bottom and then continue drilling with the liner to the required target depth. The system is comprised of a drillable fixed cutter casing bit and a drill-in liner assembly designed to handle the rigors of a drilling environment (rotation, reciprocation and drilling torque). The liner system utilizes a running tool that allows the liner to be used in drilling mode handling all the required drilling loads without fear of release. Once at desired setting depth, the hydraulically balanced liner-running tool is released with a setting ball. The casing bit is manufactured from a specialized steel alloy that allows technicians to braze polycrystalline diamond compact (PDC) cutters directly to the one-piece bit ensuring a robust cutting structure capable of efficiently drilling new formation as well as reaming existing hole. The system allowed the operator to drill in the liner to TD, cement, and then drill out to the next casing point.To date, nine intervals have been drilled with this system in South Texas. This paper will focus on the problems encountered in the field, the development work in establishing a solution for the operator, the results attained, and lessons learned through using this new technology. TX 75083-3836, U.S.A., fax 1.972.952.9435.

Summary Gravel-packing sand and formation minerals dissolve in the hot alkaline water injected with steam. This dissolution is believed to cause gravel-pack failure and other production problems. This paper describes the use of ammonium salts in reducing dissolution by reducing the pH of generator effluents from values of 11 and greater to between 9 and 10. These salts, such as ammonium chloride and ammonium nitrate, do not significantly change feedwater pH. Both laboratory and field test results are presented. This paper also presents a brief summary of other methods proposed to prevent gravel and formation dissolution. In addition, the need for more prevent gravel and formation dissolution. In addition, the need for more information about the role of silica dissolution in causing production problems is discussed briefly. problems is discussed briefly. Introduction Steam injection for the recovery of heavy oil continues to be an important recovery technique. Gravel-pack failure, casing collapse, and sand production have been identified as some of the production problems associated with steam operations. Dissolution of gravel-packing sand and formation minerals in the hot alkaline water injected with steam is believed to contribute to these production problems. problems. When steam is generated in "once-through"-type generators, a portion of the feedwater remains as liquid, carrying dissolved solids downhole with the steam. This liquid effluent becomes alkaline as bicarbonate ions, which are present in most feedwaters, decompose during steam generation to yield CO2 in the vapor phase and carbonate and hydroxide ions in the liquid phase. The pH of generator effluents often ranges between values of 11.0 and 12.5. Feedwater enters the generator with a pH that is nearly neutral. Reed demonstrated that the solubility of gravel and formation minerals increases dramatically with increased temperature and pH. The hot alkaline water injected with just one steam cycle can dissolve more than 1 ton of gravel and sand . The volume of material lost by dissolution can cause liner or casing collapse as well as sand production. Furthermore, as the hot water becomes concentrated in silicon and then cools as it flows through the formation, siliceous compounds can precipitate, potentially reducing formation permeability. In addition to the problem of silica dissolution, the elevated pH results in rock alterations that can cause formation damage.