Abstract

This paper summarizes the progress by government and industry representatives of the API Work Group on Annular Flow Prevention and Remediation in studying the causes and prevention of deepwater shallow water flows (SWF) and annular flow incidents in other wells resulting in loss of well control linked to the well-cementing process. An overview is provided on two new API recommended practice publications (RP-65 Parts 1 and 2) that describe preventive and controlling measures for SWF in deepwater wells and for any flow zone in almost any type of well. This includes key well planning, drilling, and cementing practices designed to help ensure isolation of potential flow zones. The paper also mentions plans to prepare Part 3 of RP-65 on prevention and remediation of sustained annular casing pressure during production. 

This paper introduces and promotes the use of best practices associated with prevention of annular flow incidents. It will also help inform the industry on pending regulations that may require the use of RP-65 in preparing Applications for Permits to Drill (APD) and in drilling and cementing operations in areas regulated by the MMS (Minerals Management Service) of the U.S. Department of the Interior.

The Work Group

On August 16, 2000, the MMS (Minerals Management Service) presented safety concerns on uncontrolled annular flows to a new API work group including members from or links to API Washington staff, the API Executive Committee on Drilling and Production Operations, API Subcommittee 10, ISO, IADC, DEA, DeepStar, the MMS, and other interested parties. Issues related to sustained casinghead pressure (SCP) in over 8,000 wells in the Gulf of Mexico wells were also discussed.

The MMS challenged the participants to prepare “best cementing practices” to improve zonal isolation, reduce the occurrence of SCP, and help prevent annular flows during and after cementing. The MMS would then “consider” the incorporation of these documents into federal regulations as standard practices.

In later Work Group meetings, annular flow statistics were presented including MMS records on the occurrence of SCP in Fig. 1 and on 34 LWC (loss of well control) incidents that occurred during drilling operations and reported in the years 1992 through 2002. Of the 34 LWC incidents, 19 (56%) were caused by annular flows associated with the cementing process. Fig. 2 illustrates the high cost of losing well control, especially in offshore operations.

The first charge to the Work Group was to prepare an API Recommended Practice (RP) on a zone-isolation engineering process for prevention of annular-flow events from deepwater shallow formations during and after primary cementing. In September 2002, this document was published as API RP-65 First Edition , titled "Cementing Shallow Water Flow Zones in Deep Water Wells.” This is now called “Part 1” of a three-part series of RP-65 publications.

The second charge was to prepare a second RP titled "Isolating Potential Flow Zones in Well Drilling and Cementing Operations." This will be API RP-65 “Part 2” on a zone-isolation engineering process that helps prevent well- control events during and after primary cementing caused by annular flows of water and hydrocarbons (primarily gas) from flow zones of any depth in offshore shelf wells and from deeper formations in deepwater wells. The first draft of this RP is complete and in review as of this writing.

The third charge was to prepare a third RP on a zone-isolation engineering process to help prevent SCP from formations at any depth in all types of wells. A section on remediation of SCP will be included in this publication designated as API RP-65 “Part 3.” Work on this RP will begin mid-2005.