The Minimum Space Platform Rig (MSPR)-Its Adaptability to Onshore Drilling Applications

Summary

The Minimum Space Platform Rig (MSPR TM) concept, pioneered by Pool Offshore Co. in 1969, has gained wide acceptance in the Gulf of Mexico, offshore California, and in international waters for its ability to operate within restricted space limitations on offshore drilling and production platforms. The same design features that make the concept so adaptable to a wide range of platform deck configurations have proved operationally and economically advantageous for drilling onshore, over multiwell cellars, and on such restricted locations as townsite lots and on hillsides in rugged terrain.

Introduction

In the early 1890's, the first wells drilled offshore in the U.S. were drilled from wooden piers, some up to 1,200 ft [365.76 m] long, in relatively shallow waters off Summerland, CA, near Santa Barbara (Fig. 1). The rigs used to drill off these piers were identical to those used on land. Although the method was unique at that time, the technique never proved economically viable.

Nearly a hundred years later, in the 1980's, we saw a reversal of this situation when rigs designed specifically for offshore-platform development drilling were first used onshore California. In this case, however, the technique has proved operationally and economically successful because space limitations dictated the use of some type of unconventional rig configuration.

This paper covers the design features of the MSPR rig concept and the advantages such features provide for onshore, limited-space drilling applications. Examples of several onshore drilling applications are given.

MSPR Design Features

The MSPR design was conceived with the intent to develop offshore-platform drilling or workover rigs that would have the following advantages (Fig. 2).

1. They would provide a minimal footprint on the platform deck yet have the power and hookload capabilities to compete with conventional platform rigs at comparable well depths.

2. They would be capable of "bootstrap" fig-up and rig-down.

3. They would have the capability to alter the rig configuration to meet a wide range of platform designs and deck-space limitations.

4. They would have the ability to skid, fully rigged, from well slot to well slot and center the rig package over each slot.

Fig. 3 is an explosion schematic showing the component design features of the basic MSPR rig system. The MSPR is designed to fit the standard skid beams on the platform deck. Jacking beams (or false capping beams) are superimposed over the platform skid beams. These beams contain jacking claw slots used in securing hydraulic skid jacks, which are used to move and to position the rig over the well slots.

Next are the mud tanks, which serve a dual purpose. They not only make up the drilling fluid system and provide bulk liquid storage but also serve as the primary support, or substructure, for the rig package.

A set of strongbacks is installed on top of the storage tank substructure. The strongbacks also serve a dual purpose: they form the foundation for the rig floor and pony structure for the crane and ar-e used for storage of diesel fuel and other fluids. The cantilevered pony structure serves as the base for a modular skidding crane that is used to erect the rig package components.

Mounted above the strongbacks are the rig floor and pipe walk. The rig floor package contains the drawworks, rotary table, driller's console, and other rig floor equipment.

Next is the mast base section, fitted with a wireline platform that is pinned to the rig floor for support.

Once the mast base section is secured in place, additional mast sections are erected vertically from the base section in a telescoping manner. Finally, the mast crown section is raised, using the wireline and drawworks.

These are the basic rig components. To complete the rig-up (Fig. 4), the traveling gear is strung up inside the mast, and all other components-such as pumps, engines, logging units, and bulk tanks-are installed on the platform deck or on pony structures.

Another unique feature of the MSPR design is that modular quarters buildings, including a helicopter deck and pipe racks, are cantilevered off the platform using the cantilever capping beams for support (Fig. 5).

As stated before, all rig components are erected on the platform using the platform crane initially and the modular skidding crane later. To rig down, the procedure is reversed.

Although weather, platform design, and other factors can influence erection time, an MSPR has been erected in as few as 14 days under ideal conditions.

JPT

P. 1633^