Paper: Correct Flowback Procedure A Key to Successful Foam Stimulation

The elements of a successfully planned and executed foam stimulation treatment have characteristically included surface and bottom-hole foam quality calculations, foam rheology, foam structure, surfactant and polymer requirements, pressure volume and temperature considerations, proppant transport, and fluid and nitrogen rates. Often taken for granted is the importance and advantages of foam flowback after the treatment to obtain maximum load recoveries with minimum or no proppant flowback into the wellbore or to the surface. A carefully planned and successfully used procedure is presented to allow more quantitative and precise control of foam flowback after a treatment is completed. Considerations for proper shut-in time, flowback technique, return fluid character, pressures, rates, closure stress criteria and formation damage will be made. The use of adjustable versus positive choke assemblies is discussed and advantages and procedures for the use of both are offered. Procedures for foam flowback from shallow, moderately deep and deep well treatments are recommended with considerations for bauxite and propping materials. Careful attention to the surface equipment preparation will result in obtaining maximum load recovery, with minimum proppant fill and/or flowback. This will allow the operator to realize the full benefits from the foam treatment sooner. Flowback procedures can significantly affect the resultant positioning of proppant in the packed fracture and subsequently the sustained productivity of the well. The importance of determining the closure stress requirement to enable adequate proppant entrapment in the fracture is presented. An equally important factor is the cooperation of the service company and operator in designing, and implementing these procedures. Understanding the consequences of not following these procedures is also important, and may offer clues as to why a foam stimulation job's results may not have been as good as anticipated. Key factors for determining that these procedures were not followed will be reviewed.