Paper:

SPE 60901:
Injectivity Decline in Water-Injection Wells:
An Offshore Gulf of Mexico Case Study

Authors:

Sharma, M.M, Pang, S., Wennberg, K.E. and L.N. Morgenthaler, L.N.

Venue:

This paper (SPE 60901) was revised for publication from paper SPE 38180, first presented at the 1997 SPE European Formation Damage Conference held in The Hague, 2-3 June. Original manuscript received for review 19 May 1997. Revised manuscript received 23 August 1999. Paper peer approved 8 September 1999. SPEPF, February 2000. Abstract only presented.

Summary:

A decline in injectivity in water injection wells can have a large impact on the economic feasibility of offshore water disposal operations. A case study is presented for an offshore Gulf of Mexico water injection project. Data are presented for five typical offshore wells for which a rapid decline in injectivity was observed due to water injection. The wells were successfully acidized every few months over a period of 2 years. An analysis of the data indicates that in injection wells that are not fractured, such declines in injectivity may be expected even for relatively clean injection water. A comparison of the different completion types indicates that both open hole and perforated completions would have yielded similar results. Cleaner water would have improved the situation but at a substantial cost. Fracturing the injection wells appears to be the only plausible way of substantially increasing the half life of such injectors. In cases where reservoir conditions dictate that the wells not be fractured, the economics of periodic stimulation vs. the cost of installing surface facilities for cleaning up the water should be evaluated using models for injectivity decline. "What if" simulations conducted to study the impact of different process parameters such as injected particle size and concentration, injection rate and reservoir properties were found to be a useful tool in specifying water quality requirements.

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Modified: | 6/10/2002