Abstract

This paper discusses the improvements in the drilling techniques and procedures that optimized the drilling operations in Gulf of Suez October Field. The improvements include all aspects of the operation: the drilling plans, the drilling procedures, the drilling equipment, the support procedures, the drilling equipment, the support services, and the supervision. Optimization greatly increased penetration rate, improved hole stability, and reduced time of all operations. With these results, the last group of wells were drilled almost three times faster than the early wells, and at half of their cost.

Introduction

The October Field, operated by Gupco (Gulf of Suez Petroleum Co.)., is one of the largest Egyptian offshore oil producer. The field was discovered in May 1977 while drilling the first well in block GS-195 (was lately renamed A-1). This well had commercial oil in the Lower Cretaceous Nubian Sandstone below-11000 ft (3353m) subsea. The location of the field is shown in fig. (1)*.

Three additional appraisal wells were drilled in 1977 and 1978 which established the extension of the field. This was followed by a vigorous development plan; six development platforms (nine slots each) were installed, and five jack up rigs were used between 1979 and 1985 to drill 27 development wells. The footage drilled in October field totaled over 338,000 feet (103,002m). Presently, the field gives more than 20% of the total offshore production of Gupco.

The initial drilling plans were modified from well to well to account for new data when it became available. The continuous appraisal of the drilling plans resulted in reducing rig time and drilling cost. This paper discusses Gupco's efforts in optimizing the drilling operations in the October field. As a result of these efforts, the cost of drilling any one of the last group of wells was 50% of the cost of that of the early development wells.

II. FIELD GEOLOGY AND ASSOCIATED DRILLINGDIFFICULTIES

Fig. (2) shows a typical stratigraphic section in October field; a brief summary of the drilling parameters is also included. parameters is also included. The formations in October field are Post Miocene (Recent) clastics, Miocene evaporite and clastics, and Pre-Miocene clastics. Each of the three rock groups represents almost one third of the drilled section.

Top Recent deposits wash out easily around the surface conductor, become unstable with time, and have high seepage losses. The bottom intercalculations become more competent as they near the top of Miocene deposits.

The Miocene has two distinct sections of equal thickness: the evaporites, and the clastics. The following are the important difficulties of drilling into the Miocene Evaporites:

  1. High torque and bit walk in the topanhydrite-shale section.

  2. Active salt creep in the massive salts.

  3. Slow drilling, and about 13 lbm/gal (1558kg/m3) salt water flow in South Gharib-Belayimseparation.

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