The Stim-Lab/Owen Oil Tools Perforating Consortium investigates the extent of perforating damage as a function of shaped charges, lithology, rock mechanical properties, original formation permeability and porosity. The objective is to develop a correlation that can predict permeability alteration during perforation. Prior knowledge of permeability damage allows proper selection of a shaped charge for a particular formation thus increasing well productivity. Stim-Lab and Owen Oil Tools invite you to become directly involved by participating in this joint venture.

Summary
The perforating consortium is a joint effort between Stim-lab and Owen Oil Tool. The project begins in July of 1999 as a three year project. Initial funding from the Oklahoma Center for the Advancement of Science and Technology (OCAST) has been received amounting to $300,000.

The objective of the perforating studies is to develop a set of correlations that predict formation damage surrounding the perforation tunnel vs. formation and charge properties.

The tasks in the project include:

1. Experimental investigation to characterize formation damage with core flow efficiency and analyses as a function of factors such as shaped charge strength, type of shaped charge, lithology, original formation permeability, original formation porosity, and rock compressive strength.
2. Perforation Cleanup Studies will be conducted to identify the most effective acidizing and back-flow methods to maximize flow.
3. Develop a set of theoretical correlations from the laboratory data. These correlations will be integrated into current perforation flow models to predict the impact of perforating on well productivity.

 The equipment available for the experimental studies includes an API section 4D perforating and core flow efficiency cell. Various strength levels of perforating shaped charges will be used to perforate samples with a range of properties with the assistance of Owen Oil Tools. Each perforated sample will be prepared for qualitative and quantitative analysis using SEM, image analysis method, EDS, and a polarized microscope to evaluate the effect of shock waves on rock grains. The SEM will allow qualitative analysis of crushed zone formed during jet perforation both laterally and radially, the image analysis method will be used to measure porosity and permeability of the damaged zone. EDS will be used for chemical composition and concentration determination of debris left behind in the perforation tunnel. Shock metamorphism phenomenon will be applied to the shocked grains to evaluate the effect of shock waves on shocked grains and, hence, porosity reduction. Core flow efficiency tests will be performed on each sample. The perforating and core flow cell is instrumented to measure the pressure drop in the injection and the production directions before and after perforating. Under cleanup, methods such as back-flow, the injection of HCl and HCl: HF and perforating in acid will be evaluated on selected samples. The correlations of damage vs. formation and charge properties will be useable in currently available perforating programs as a damage and cleanup module. With this information, actual data can be used to predict damage factors for previous and future perforating jobs allowing the engineer to select a set of charges and cleanup methods to optimize well productivity.

Introduction
Stim-Lab. Inc., a research organization, and Owen Oil Tools, a pioneer in shaped charge designs, manufacturing, and application, have joined to form the Perforating Damage Assessment/Prediction Consortium. The program is committed to experimentally assess the extent of perforating damage using the API RP-43 section 4, and to develop a correlation that can predict crushed zone permeability as a function of shaped charge level of strength, lithology, rock mechanical properties, formation permeability and porosity.

Experimental Work

• Perforation of various formations with various shaped charges
• Qualitative analysis of the crushed zone with SEM
• Quantitative analysis of crushed zone with image analysis
• Shock wave detection around the perforation tunnel based on the shock metamorphism method
• Chemical composition/concentration determination of debris with EDX and XRD

Facts
In shaped charge jet perforation, the detonation of an explosive charge containing a conical depression creates a sharply focused intense pressure pulse that can exceed 4x106 psi at a velocity of 30,000 ft/sec. This pulse of hot explosion gas pushes aside all material in its way as it is traveling forward into the formation.

As effective as this process is in creating a hole or tunnel, it alters the rock formation around the ¼ to ½ inch diameter tunnel, which is created. This altered, compacted or crushed zone is believed to be responsible for permeability of the zone being significantly less than virgin formation by as much as 80%.

It is therefore essential to be able to accurately and scientifically predict perforating damage zone permeability so that a proper shaped charge can be selected for a particular formation. The capability to accurately predict the extent of formation damage as a result of perforation yields to:

• Better design of shaped charges
• Better selection of shaped charges for a particular formation
• Better design of perforating job, and
• Higher well productivity

Deliverable

• A correlation that can predict perforating damage as a function of shaped charge level of strength, lithology, rock mechanical properties, formation permeability and porosity.
• A user-friendly computer software package integrated with the developed correlation and a database where various parameters can be selected to calculate perforating damage.

Membership
The study is constructed for a 3-year period with the potential to continue. The consortium will hold two meetings per year where results of preceding 6 months findings will be presented. The results will be available only to the members.

Stim-Lab encourages new members so that research continues adding value to participating company's lines of business. Membership grants access to the "members only" web site which contains research updates, reports for download, plus any programs or spreadsheets developed within the program.