Novel Downhole Methods And Compositions Used in Such

A method for the stimulation of a hydrocarbon-bearing formation, said method comprising the steps of:

• providing a wellbore in need of stimulation;
• inserting a plug in the wellbore at a location slightly beyond a predetermined location;
• inserting a perforating tool and a spearhead or breakdown acid composition into the wellbore positioning the tool at said predetermined location;
• perforating the wellbore with the tool thereby creating a perforated area;
• allowing the spearhead acid to come into contact with the perforated area for a predetermined period of time sufficient to prepare the formation for fracking or stimulation;
• removing the tool form the wellbore;
• and
• initiating the stimulation of the perforated area using a stimulation fluid,
• wherein the acid composition comprises a corrosion inhibitor package comprising at least two compounds selected from:
• Group A;
• Group B;
• Group C;
• Group D;
• Group E;
• Group F;
• Group G;
• Group H;
• and Group I, where the at least two compounds are selected from different groups and where:
• Group A comprises compounds encompassed within the following general chemical description:
• α,β-unsaturated aldehyde;
• Formaldehyde;
• Cinnamaldehyde;
• Group B comprises compounds encompassed within the following general chemical description:
• acetylenic compound;
• unsaturated alcohol;
• acetylinic alcohol;
• alkoxylated acetylenic alcohol;
• alkoxy phenols;
• diacetylenic alcohols;
• Group C comprises compounds encompassed within the following general chemical description:
• group 15 metal (bismuth, antimony);
• antimony compounds;
• germanium compounds;
• Group D comprises compounds encompassed within the following general chemical description:
• sulfur-containing compounds;
• mercapto-compounds;
• organosulfur compounds
• reaction products of thiourea;
• thiodiglycol alkoxylates;
• Group E comprises compounds encompassed within the following general chemical description:
• nitrogen-containing surfactant;
• and
• non-ionic surfactant;
• Group F comprises compounds encompassed within the following general chemical description:
• morpholine;
• aminoalkyl imidazolines;
• sarcosine;
• two linked cyclic molecules with at least one nitrogen heterocycle (e.g. quinoline+benzyl);
• imidazoline;
• and
• alkyl pyridine;
• Group G comprises compounds encompassed within the following general chemical description:
• aromatic ketone;
• amide;
• and
• phenyl ketone;
• Group H comprises compounds encompassed within the following general chemical description:
• heavy aromatic solvent;
• Group I comprises compounds encompassed within the following general chemical description:
• carboxylic acid-containing compounds;
• and
• nitro-aromatic compounds with at least 1 carboxylic acid group, said compounds preferably selected from the group consisting of dinitrosalicylic acid, nitrophthalic acid, mononitroterephthalic acid and dinitroterephthalic acid effective to inhibit corrosion of the steel.