A multi-functional jetting tool can be installed within a tubular work string, or attached to the distal or leading end of the tubular work string, in order to facilitate improved cleaning of downhole and/or subsea equipment—and particularly equipment with internal recesses, cavities or crevasses. A bull nose cap member, which can be constructed of plastic or other non-abrasive material, can be attached when the jetting tool is run on the distal end of a tubular work string. Fluid jetting ports can be selectively equipped with standard-sized or adjustable nozzles, thereby permitting customized fluid jet flow pattern from the jetting tool along the tool body in multiple directions for desired applications.

The invention relates to a method of conducting a perf wash cement (“P/W/C”) abandonment job in an offshore oil or gas well annulus (2), in particular the washing or cementing operation using a rotating head (6, 8) with nozzles (7, 9) dispensing wash fluid or cement at pressure. Certain values of parameters of a washing or cementing job have been found surprisingly to affect the quality of the job, or the degree to which they affect the quality of the job has been unexpected. These include including rotation rate of the tool, the direction of translational movement of the tool, and the volume flow rate and pressure per nozzle of cement or wash fluid (and hence nozzle size).

A system for measuring a porosity of a gravel pack in a wellbore includes a transmitting acoustic transducer attached to a sand screen and configured to transmit an acoustic signal. The system further includes multiple acoustic transducers attached to the sand screen and configured to receive the acoustic signal through the gravel pack. The system also includes a control device configured to receive electrical signals from the multiple acoustic transducers and determine the porosity of the gravel pack around the sand screen based on at least the electrical signals. The electrical signals are generated from the acoustic signal received by the multiple acoustic transducers.

A system for measuring a porosity of a gravel pack in a wellbore includes a transmitting acoustic transducer attached to a sand screen and configured to transmit an acoustic signal. The system further includes multiple acoustic transducers attached to the sand screen and configured to receive the acoustic signal through the gravel pack. The system also includes a control device configured to receive electrical signals from the multiple acoustic transducers and determine the porosity of the gravel pack around the sand screen based on at least the electrical signals. The electrical signals are generated from the acoustic signal received by the multiple acoustic transducers.

Methods and systems for treating wellbores. An example method includes introducing an acidic treatment fluid into the well; wherein the acidic treatment fluid comprises an acid and a first aqueous base fluid. The method further includes introducing an enzymatic treatment fluid into the well; wherein the enzymatic treatment fluid comprises an enzyme and a second aqueous base fluid. The method additionally includes contacting the filter cake with the acidic treatment fluid and contacting the filter cake with the enzymatic treatment fluid after the filter cake was contacted with the acidic treatment fluid.

Methods and systems for treating wellbores. An example method includes introducing an acidic treatment fluid into the well; wherein the acidic treatment fluid comprises an acid and a first aqueous base fluid. The method further includes introducing an enzymatic treatment fluid into the well; wherein the enzymatic treatment fluid comprises an enzyme and a second aqueous base fluid. The method additionally includes contacting the filter cake with the acidic treatment fluid and contacting the filter cake with the enzymatic treatment fluid after the filter cake was contacted with the acidic treatment fluid.

A method and reactive treatment fluid for treating a wellbore for filter cake removal, including providing the reactive treatment fluid having a viscoelastic surfactant (VES) into a wellbore in a subterranean formation and attacking the filter cake via the reactive treatment fluid.

A method and reactive treatment fluid for treating a wellbore for filter cake removal, including providing the reactive treatment fluid having a viscoelastic surfactant (VES) into a wellbore in a subterranean formation and attacking the filter cake via the reactive treatment fluid.

A method of preventive well maintenance with pumping equipment in the well for well rehabilitation using CO.sub.2 with varying lengths of producing intervals utilizing varying methods to deliver cleaning energy and varying porosity of aquifers to determine varying quantities of energy over the entire well structure.

A method of preventive well maintenance with pumping equipment in the well for well rehabilitation using CO.sub.2 with varying lengths of producing intervals utilizing varying methods to deliver cleaning energy and varying porosity of aquifers to determine varying quantities of energy over the entire well structure.