Surface BOP: Testing and Completing Deepwater Wells Drilled With a Surface BOP Rig

Abstract

Many deepwater development projects in Operators' portfolios require lower costs to meet internal economic thresholds. Shell has therefore looked at extending Surface BOP activities to include well testing and completion techniques for deepwater wells in conjunction with Surface BOP drilling. The cost advantages of Surface BOP drilled wells have been demonstrated (notably in the Far East), but the recent Surface BOP drilled Brazil well is a milestone in terms of extending the applicability to deeper water and harsher environments. The enabling technology has been the Subsea Disconnect System (SDS). Testing and completion techniques have therefore been developed to be compatible with Surface BOP wells drilled with an SDS. The paper will focus on the following aspects:Well testing using Surface BOPs from a moored rigWell Completions using Surface BOPs from a moored rig Shell has developed a testing configuration to carry out a DST essentially using standard equipment. The well testing equipment configuration is currently ready for use, waiting for the opportunity to be run. In completion operations, the availability of a high pressure riser does not add significant complexity and even actually simplifies some of the completion activities. Conceptual studies and early hazard/risk assessments have shown there are no obvious showstoppers and the duration of a Surface BOP rig completion is expected to be very similar to a subsea BOP rig completion. The paper describes the results of the conceptual studies, early hazard assessment exercises used to define the basic design parameters and more detailed hazop studies. Introduction As deepwater exploration and development move into ever deeper water and arduous environments, operators are looking at ways to reduce well costs to make prospects and developments economically more attractive. One of the key avenues seen to do this is to accomplish drilling, testing and completing wells using smaller deepwater rigs, with a consequent reduction in rig rates. To date, most ultra-deepwater wells (where water depth >5,000ft) have been executed using the latest generation of new or converted drilling vessels (these will be referred to as "Generation V" rigs). Over 150 subsea wells in varying water depths have now been executed using floating rigs with Surface BOPs in locations around the world. A semi-sub (Sedco-135) was used to drill a subsea well using Surface BOPs offshore Nigeria in EA-3 in 1967. Since then, a number of operators have pioneered the use of Surface BOP with moored rigs in the Far East, in benign environmental conditions. Shell have recently used Surface BOPs on a Generation IV DP rig to extend the 7,500ft water depth capability of the rig - drilling a deepwater exploration well in 9,474ft of water offshore Brazil (ref. 1). The trend is to take this technique and apply it in a number of deepwater operating areas with older Generation III and IV rigs which were not specifically built for deepwater operation. This paper will outline the well testing and well completion approaches that are planned to meet these challenges. The overall Surface BOP system will be described, then well testing and well completion methodologies will be described. It should be noted that these methodologies are being worked on and refined in an ongoing manner, once actual experience is gained, they will of course change and be optimized further.

The Application of BOP During Oil Well Drilling

“…However, the advantages of a float valve are many. Kicks will not enter the drill string during tripping or when drill pipe is open at the surface [2] . Good volume control is achieved when tripping into the well.…”