Salt water Gel Packer Fluid for High Pressure Completions

Abstract

This paper was prepared for the 48th Annual Fall Meeting of the Society of Petroleum Engineers of AIME, to be held in Las Vegas, Nev., Sept. 30-Oct. 3, 1973. Permission to copy is restricted to an abstract of not more than 300 words. Illustrations may not be copied. The abstract should contain conspicuous acknowledgment of where and by whom the paper is presented. Publication elsewhere after publication in the JOURNAL OF PETROLEUM TECHNOLOGY or the SOCIETY OF PETROLEUM ENGINEERS JOURNAL is usually granted upon request to the Editor of the appropriate journal provided agreement to give proper credit is made. Discussion of this paper is invited. Three copies of any discussion should be sent to the Society of Petroleum Engineers office. Such discussion may be presented at the above meeting and, with the paper, may be considered for publication in one of the two SPE magazines. Abstract Past completion techniques in the middle Past completion techniques in the middle to lower miocene abnormally pressured gas sands in the Gulf Coast area have involved the use of a weighted mud as a packer fluid. Workovers on these wells incur extremely high costs associated with recovery of tubing stuck in settled mud solids. To reduce the workover costs and expense of lost or damaged tubing, packer fluid requirements were reexamined to select a fluid that would prevent these problems. Two unweighted systems were selected from an overall review and comparative tests were run to determine long term stability, sealing properties, and handling ease. Results of the properties, and handling ease. Results of the tests determined a suitable solution for use in Gulf Coast high pressure completions. A fluid composed of 25#/bbl. attapulgite gel in a saturated saltwater solution with a chromate corrosion inhibitor and the pH adjusted to 10.5 with soda ash showed a clear superiority. It has been used in Gulf Coast wells for three years and field experience in producing and workover situations has supported producing and workover situations has supported the test results. Introduction It has been standard practice to use drilling mud as a packer fluid in high pressure wells in many companies since that type completion was first made. The apparent advantages of drilling mud are:The fluid is available at no additional cost.In the event of a tubing leak, the hydrostatic column may be sufficient to kill the well and may avoid troublesome casing pressure.In the event of a casing leak, drilling mud solids have excellent sealing characteristics against moderate differential pressures. The disadvantages of drilling mud packer fluids, however, appear later in the life of the well and have a significant effect on workover costs. The problems surface in the following forms:Barite settling results in extensive fishing operations to pull the tubing.High temperature gellation of lime base fluids requires washover operations to clean out the well.Lignosulfonate degradation to H2S in lower pH environments causes tubular stress failures.