Shell has used BFS cements on over 160 oil well cementing operations as part of an effort to develop end expand the understanding of blast furnace slag (BFS)-based cements. Well types include major deepwater development wells to sidetracks drilled with a workover rig. Downhole conditions range from cold deepwater applications to shallow thermal wells subjected to cyclic steam injection.To date, the field performance of slag-based cement has met or exceeded expectations. Formation integrity tests, bond logs, and production data indicate good annular isolation. Caaingshoe integrity test datafrom exploratory and development wells showa lower incidence of remedial squeezing prior to drilling ahead es compared to Portland cements. Contrary to previously reported bond-log evaluations, conducted under laboratory conditions, downhole bond logs under saturated conditions indicate an improved caeinglcement bond with time. Production data from wells with dual comoletirms indicate mod mnnl iw-dnt.innhot.wamperforated intervals. Leak-offtestdatafor slag-based cementjobs conducted in the Gulf of Mexico are reported for each casing size. Field data for squeeze cementing casing shoes, liner tops, and casing annuli are also presented.
Shell Development Co.; Kazem JavanmardL* Shell Offshore Inc.; and R.E. Wyant, Consultant q SPE Metnbem -M law, sPEnAocOrilling cduenoe. Thk$p8per vmpropwd Iorpre8enIatbn aItha lSS5SPE/lAOC OrillingCo@aenw hold in Amswdwn, 2S F9bnMwy-2Maroh 1SS5.
She1 1 Offshore Inc. (SOI) has successfully installed and operated the Soft Torque Rotary System (STRS) f o r the f i r s t time on two d r i l l i n g rigs operating in Mobile Bay. Application of the STRS has significantly reduced torque fluctuations (up t o 8O%), torsional d r i l l string vibrations, and b i t slip-stick conditions. The STRS attenuates and interrupts the torsional oscillations of the d r i l l string and t h u s prevents the buildup of energy i n torsional waves that are reflected back and forth between the b i t and the rotary table. I t can be installed on any r i g equipped with an independent electronically driven rotary table or top drive. The STRS i s inexpensive (about $25M f o r Shell group companies), easy t o i n s t a l l , and has been a factor in improved dri 11 ing penetration rates realized on the SL 531 No. 3, a complex directional well drilled in the Mobile Bay area. Additionally, the STRS has been instrumental in avoiding expensive ($5MM-$lOMM) d r i l l string failures on the SL 531 No. 3. Further work needs t o be done t o f u l l y quantify the impact of the STRS on reducing these types of failures.
Blast furnace slag is a unique hydraulic material which is a by-product of the steel-making process. A new method of mud to cement conversion technology utilizing slag as the hydraulic material has been developed, and the technical merits of this slag mix are briefly reviewed. This slag mix technology is economically, technically, and environmentally superior to conventional Portland cements and has been used in many fields. The major environmental benefit is the reduction of mud disposal volume. Since the application of slag mix at Prospect Auger in the Gulf of Mexico, excess whole mud discharge has been reduced by about 70% (4,530 barrels per well). Approximately 15,000 barrels of excess drilling mud was recycled into slag mix at Auger. In addition, a new drilling waste management method to reduce or eliminate drilling waste at the rig-site has been developed. A new type of slag-supplemented drilling fluid containing 40 to 60 lb/bbl slag can produce slag-laden cuttings which are self-setting with time. The in-situ solidification method seems to be environmentally acceptable and potentially cost-effective. Introduction Drilling waste management is a growing concern for the industry. Current drilling fluid and cuttings disposal methods are being challenged by an increasing number of federal, state, and local regulatory agencies. The drilling industry is therefore seeking more environmentally acceptable and cost-effective methods for drilling fluid and drilled cuttings disposal. Excess drilling fluid can be converted to a cement using slag (1) to provide an improved seal in the annulus between the borehole wall and casing and (2) to provide adequate structural support for the casing. For simplicity, this in-situ mud conversion technology will be referred to as slag mix or slag-mud slurry in this paper. The objective of this paper is to present the environmental advantages of slag mix technology and to demonstrate the technical merits of a new drilling waste management method using slag. A unique waste management concept was formally introduced by Congress as a regulatory concept in the 1984 Hazardous and Solid Waste Amendments to the Resource Conservation and Recovery Act (RCRA) of 1976. The 1980 RCRA amendments exempted oil industry exploration and production (E and P) wastes from regulation under the RCRA Subtitle C (40 CFR 261-265) hazardous waste provision. Subtitle C identifies hazardous chemicals in two ways - by listing and by definition. One group of wastes exempted from regulation as hazardous waste is drilling fluids, drilled cuttings, produced water, and other waste associated with crude oil and natural gas exploration, development, and production. Since most E and P wastes are non-hazardous, they are regulated as subtitle D (40 CFR 256-257) solid waste under RCRA and the regulations of the various oil-producing states. While the exemption lifts many of the burdens of RCRA Subtitle C (hazardous waste) requirements, it remains the operator's responsibility to assure adequate protection through proper waste management practices. The goals of the RCRA program are to encourages solid waste management practices that (1) promote environmentally sound disposal methods, (2) maximize the reuse of recoverable resources, and (3) foster resource conservation. P. 443^
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