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Title: Well stimulation in the North Sea

A survey of the well stimulation techniques applied in the past 6 yr in the gas wells of the southern North Sea basin indicates that fracturing is more effective in lower permeability wells and matrix acidizing in wells with better permeability. Wells in the indefatigable and Leman fields (Rotliegendes) required treatment only for formation damage removal, in the West Sole (Rotliegendes) field they required fracture stimulation, and in the Hewett (Bunter and Hewett sandstone) and Viking (Rotliegendes) fields they achieved optimum production without stimulation or treatment. Wells of higher permeability generally showed high formation damage following initial completion. The majority of the matrix acidizing treatments used an acid formulation of 85 vol percent of 15 percent HCl and 3 percent HF, plus 15 vol percent of isopropyl alcohol. Perforation ball sealers with a 1.1 specific gravity were distributed throughout the acid to distribute it over the entire perforated intervals. Pump rates varied from 8 to 22 rpm, depending on the thickness of the perforated interval. The effect of each treatment was then evaluated by acid response coefficient (ARC) curves. Fracture treatments were applied to 27 wells, all in the Rotliegendes formation. Selection of the fracturing fluids depended on the availability,more » friction-loss properties, carrying capacity, leakoff rate, and compatibility with the reservoir formation. Proppants used included sand, walnut shells, glass beads, and their combination. Results of each stimulation treatment were evaluated by considering each well's pre-frac, immediate post-frac, and recent performance.« less
Authors:
;
Publication Date:
OSTI Identifier:
6925044
Resource Type:
Journal Article
Resource Relation:
Journal Name: Pet. Eng. Int.; (United States); Journal Volume: 12
Country of Publication:
United States
Language:
English
Subject:
02 PETROLEUM; 03 NATURAL GAS; NATURAL GAS WELLS; ACIDIZATION; FRACTURING; NORTH SEA; OIL WELLS; ENHANCED RECOVERY; HYDROCHLORIC ACID; HYDROFLUORIC ACID; NATURAL GAS; PETROLEUM; PROPANOLS; PROPPING AGENTS; WELL STIMULATION; ALCOHOLS; ATLANTIC OCEAN; COMMINUTION; ENERGY SOURCES; FLUIDS; FOSSIL FUELS; FUEL GAS; FUELS; GAS FUELS; GASES; HYDROGEN COMPOUNDS; HYDROXY COMPOUNDS; INORGANIC ACIDS; ORGANIC COMPOUNDS; SEAS; SURFACE WATERS; WELLS 020300* -- Petroleum-- Drilling & Production; 030300 -- Natural Gas-- Drilling, Production, & Processing