Downhole methods and compositions used in such

A method to prepare a hydrocarbon-bearing formation for a stimulation operation, said method comprising:

• step a) providing a wellbore having a casing;
• step b) assessing at least a first location and a second location for perforation of said casing;
• step c) inserting a bottom hole assembly into said wellbore;
• said bottom hole assembly comprising a plug and a perforation tool and said bottom hole assembly being connected to a wireline;
• step d) injecting a spacer fluid into said wellbore;
• step e) injecting an acidic composition into said wellbore;
• wherein said spacer fluid separates said acidic composition from said bottom hole assembly, and wherein said acidic composition is in direct contact with both said wireline and casing:
• step f) positioning and setting said plug in the wellbore at a position downhole but proximate to said first location;
• step g) positioning the perforation tool at said first location;
• step h) perforating said casing at said first location with the perforation tool thereby creating a first perforated area and a first cementitious debris;
• step i) pumping a displacement fluid to displace said acidic composition to contact said first perforated area and first cementitious debris;
• step j) causing the acidic composition to come into contact with said first perforated area and said first cementitious debris for a predetermined period of time to prepare the formation for said stimulation operation;
• step k) moving the perforation tool up-hole to said second location;
• step l) perforating said casing at said second location with the perforation tool thereby creating a second perforated area and a second cementitious debris;
• step m) causing said acidic composition to come into contact with the second perforated area and said second cementitious debris for a predetermined period of time to prepare the formation for said stimulation operation;
• step n) removing the perforation tool from the wellbore;
• wherein said acid composition comprises a urea-HCl acid and a corrosion inhibitor package, said corrosion inhibitor package comprising at least two compounds selected from:
• Group A;
• Group C;
• Group D;
• Group E, wherein the at least two compounds are selected from different groups and wherein:
• Group A comprises compounds encompassed within the following general chemical description:
• α,β-unsaturated aldehyde;
• Formaldehyde;
• Cinnamaldehyde;
• Group C comprises compounds encompassed within the following general chemical description:
• a group 15 metal including 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.