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Notice to Lessees and Operators (NTL) of Federal Oil, Gas, Well Naming and Numbering Standards NOTE: Exhibits for Attachment to NTL 2000-N07 is available for download in Adobe's Portable Document Format. The Minerals Management Service (MMS) uses four distinct names and numbers to uniquely identify each well, wellbore, and well completion. They are:
We primarily use the API well number and producing interval code to manage digital data. The OCS lease number, well or well completion name, and well name suffix are still prevalent in reports, surveys, correspondence, and verbal communications. This document includes definitions, instructions, and exhibits showing how we determine well names and numbers for wells located in the offshore Federal areas that MMS manages. The examples include many of the unusual or new types of wells, well completions, and producing situations where applying the standards is more complicated. The MMS District Offices assign and/or establish this nomenclature when well permits, notices, and reports are approved and/or processed. Additional examples can be found in the MMS Field Operations Reporters Handbook which provides specific guidance on how to prepare and submit well permits, notices, and reports to the District Offices. The Handbook is available from the Regional Public Information Offices and the website http://www.gomr.mms.gov/homepg/mmsforms/reportershandbook.pdf. This standard makes several changes to, and supersedes, previous MMS standards. However, you should not file corrected permits, notices, or reports solely to comply with these changes. When we discover, or you identify to MMS, an unnumbered drilled hole, we will assign an MMS API number according to this standard if we have the basic data describing the well, such as offshore area, block, lease number, relevant dates, and key measured depths. Definitions Bypass - a remedial drilling effort in which portions of a hole are redrilled around junk (i.e., lost tools, pipe, or other material blocking the hole), "lost holes" are redrilled, or "key seats" or "crooked holes" are straightened. This is also called a mechanical sidetrack. (See Exhibit 3.) Capacity well - a well completion with two or more tubing strings producing or capable of producing from the same reservoir. (See Exhibit 10.) Horizontal well - a well with a borehole whose angle of deviation is 75 degrees or greater for more than four consecutive directional survey points. (See Exhibit 13.) Multilateral well - a well with two or more wellbores, usually but not necessarily drilled and completed horizontally or highly directionally, sharing common surface casing. (See Exhibit 14.) Sidetrack - a drilling effort in which an additional hole is drilled by leaving a previously drilled hole at some depth below the surface and above the total depth. A whipstock or cement plug is set in the previously drilled hole, which is the starting point for the sidetracking operations. The drilling of a well after a slot reclamation (which previously had a well) is considered a sidetrack. This section of the hole is directionally drilled to a new objective bottomhole location (target). This is also called a geologic sidetrack. (See Exhibit 1.) Splitter wells - two or more wells drilled, cased, and completed, sharing a common borehole at the surface but allowing independent production and individual access to each well. (See Exhibit 15.) Well - one or more wellbores drilled into the Earth for the purpose of either finding or producing underground resources or providing services related to the production of underground resources. Wellbore/borehole - a unique, oriented hole from the bottom of a drilled interval to the surface. If more than one path exists from a surface location to bottom hole point(s), then more than one wellbore exists. Well completion - a distinct physical arrangement within a wellbore that provides an isolated conduit for the production or injection from/to one or more sets of perforations or open hole intervals. API Well Number For offshore Federal operations, MMS assigns API numbers according to the "API Well Number and Standard State and County Numeric Codes Including Offshore Waters, API Bulletin D12A" (published in January 1979); and the instructions and examples in this document. Where these two differ, this document supersedes the API standard. The differences result from when MMS issued NTL 97-2N in 1997, and we began issuing API numbers to new bypasses and assigning API numbers to historical bypasses to better manage the data collected from drilling operations. API Bulletin D12A recommended reserved sidetrack codes for remedial sidetracks only be assigned for proprietary use by companies and data systems. The D12A committee did not anticipate that we would want to manage the data as well. We assign the API number to the original wellbore(s) when we approve Form MMS-123, Application For Permit To Drill (APD). We assign API well numbers for subsequent sidetracks and bypasses with Form MMS-124, Sundry Notices and Reports on Well. We sequentially increment the wellbore (WB) codes, consisting of the 11th and 12th digits of the API well number, for each subsequent wellbore (sidetrack or bypass) drilled. This includes all sidetracks and all bypasses for which you collect any geologic data (well logs, velocity surveys, core analyses, etc.), or you run any directional surveys.
The standard format 12-digit API well number is structured as follows: State County Sequence WB
For various reasons in the past, we did not assign MMS API numbers to some sidetracks and bypasses, and we accepted well name suffixes on various documents without any validation. For historic wells without MMS API numbers or validated well name suffixes, we will validate existing operator nomenclature or assign new names and numbers using WB codes in the range 70-89 when we obtain supporting data. (See Exhibit 3.) We will not change existing API numbers already assigned, including WB codes, to comply with this standard. If we have not assigned an API number for an OCS well, or if an operator or MMS cannot find the API number, then we will assign a temporary sequence number between 85,000 and 90,000 for the operator to use until we locate the permanent number or the appropriate District Office assigns a permanent number. Producing Interval Code We establish the producing interval code, sometimes referred to as the completion code, for each well completion when we accept and process Form MMS-125, Well Summary Report.
Note: In the case of a tubingless or other completion where production from one reservoir flows through a tubing string and production from another reservoir through the annulus, the first alpha character of the producing interval codes will be D. In this case, this does not signify the presence of two tubing strings, but indicates there are two separate production streams with the annulus acting as a tubing string. (See Exhibit 7.) The numeric portion is uniquely and permanently related to a specific completion zone or producing configuration within a wellbore. You select the numbers sequentially beginning with the number "01" for the first reservoir completed within a wellbore, followed by consecutively increasing numbers assigned to successively completed reservoirs. For example, a producing interval code of "S01" indicates the first reservoir completed in the well; "S02" indicates the second reservoir completed. If, however, additional perforations are added to an "S01" completion in the same reservoir, the producing interval code remains "S01" since the completion is still producing from the same reservoir or commingled situation. The components of the producing interval code are: 1st Character 2nd and 3rd Characters (Indicates No. of Tubing Strings) (Indicates Reservoir Completed)
Use a producing interval code of "X01" when reporting only the wellbore, as in the following cases: 1. Reporting an active or inactive drilling well. 2. Reporting a wellbore in which all completions have been abandoned but the wellbore itself has not been abandoned (e.g., temporary abandonment). 3. Reporting a wellbore that has been permanently abandoned. Largely because of new technology, special completions and producing situations exist that require exceptional naming and numbering guidelines. In part, we address these cases by reserving and using blocks of producing interval codes for well completion identification purposes. These reserved producing interval code ranges are identified as: Producing Interval Code Reserved For
OCS Lease Number/Well and Completion Name The OCS lease number is the MMS assigned identification for the lease at the targeted total depth of the well. The OCS lease number will change for wells subsequently (re)completed to another leased area.
Well Name Suffix The well name suffix is an extension to the well name; it identifies each wellbore and indicates the number of times a well has been sidetracked and a wellbore has been bypassed. You provide and we approve the well name suffix on Form MMS-124, Sundry Notices and Reports on Well, to each subsequent wellbore drilled.
Well Numbering Examples Examples of the correct well numbering standards are demonstrated on the attached exhibits. They include:
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