Although wellbores have been intersected before - both through planned intersections for the purpose of well control and through unplanned wellbore collisions - they have not been intersected for the purpose of actually joining their wellpaths to effectively create one smooth continuous conduit from one surface location to another. There is just one exception: the very large conduit between England and France! The purpose of this paper is to review the planning and execution of what is believed to be the world's first planned successful joining of two such horizontal wells, with a slotted liner to casing connection in between them. Introduction This paper gives a review of the scope of this project and of its desired outcome. The review will include a description of the plans for the wells including their trajectories and depths. Also included is a discussion of pre-planning activities with emphasis on the technology that was expected to make the planned intersection a success. This paper will discuss testing the specialized equipment needed to enable the intersection, mock ranging tests necessary to know the positions of the wells relative to each other, and the accuracy achieved through modified use of magnetic ranging techniques. Finally, rigsite operations will be reviewed, problems encountered will be discussed, and the lessons learned pertinent to similar efforts in the future will be disclosed. Project Goals and Objectives As with any trial or development of new technology, clear goals, objectives and expectations must be identified prior to design and implementation. It was clear from the onset that this was to be a producing well, and, as such, sand control was a concern. The intersection of the two wellbores was strictly for science and had no value to the actual production of the originally planned wellbore. The value obtained was the knowledge of what could be accomplished, so that future implementation of the technology could be considered for strategic planning purposes. Following this line of thought, the goals of this project were laid out as follows:Apply current directional drilling technology to see if two horizontal wellbores could be intersected end to end. Success was defined as intersecting the two wellbores with the drill bit and being able to enter the wellbore of the second well with the drilling assembly.Run standard steel casing through the intersection to prove that the two wellbores could be linked with solid tubulars. Success was defined as being able to run regular 7-in. casing through an 8 3/4-in. intersection point without getting the casing stuck in the hole.Join the two casing strings with a connection technique that eliminated sand production. It was agreed that the connection technique used on this first well would be as simple as possible. If this initial trial was successful, future work could be done on a more advanced connection technique. Reservoir Description / Surface Location The location selected for the trial of this technology was on land in an unconsolidated sandstone reservoir. The reservoir was only 195 m true vertical depth (TVD). The original field development plan called for several horizontal wells to be drilled under a river running through the field. It was decided that one of these horizontal wells would be an excellent location to test out this technology, as only one additional well would need to be drilled and connected to the currently planned well. Since one well was already planned to be drilled from one side of the river, a second surface location was selected on the opposite side of the river. This arrangement placed the two surface locations approximately 430 m from each other.

The purpose of this paper is to review the planning, execution and results of a Seven Leg, Semi-short Radius Multilateral Well drilled underbalanced in a very mature field in Northeast Brazil. It will explain such details as ... why multilateral?? ... why semi-short radius?? ... why underbalanced?? ... in an effort to explain the many thought processes and considerations when designing and planning drilling operations in depleted reservoirs. Introduction The Carmopolis Field is located approximately 60km northeast of the city of Aracaju, in the State of Sergipe, Brazil. It is a very mature field that covers an area of approximately 140 square kilometers, and was discovered in 1963. The field has multiple pay zones with a total of approximately 350 million m3 of oil in place. To date, approximately 62 million m3 of oil has been produced and the field currently produces about 3000 m3/day of oil and 18000 m3/day of water. The field has gone through various phases of production enhancement scenarios over the past 20 years. Enhanced recovery methods such as water flood and steam injection have been implemented in various parts of the field. New techniques and technologies continue to be used in this field in an effort to enhance production and reservoir recovery even further. The combination of underbalanced drilling and ML technology is just one more step in the evolution of this field. Reservoir Description The Carmopolis reservoir is composed of syntectonic conglomerates and associated finer clastic sediments deposited in an alluvial-fan complex within fault bounded grabens(1). There are four major lithofacies which are part of the Cretaceous period. Each of these lithofacies can be distinguished on the basis of grain size, which decreases progressively in the direction of the sediment movement. The larger grained lithofacies have lower porosity and higher bulk density which allows identification of each lithofacie based on bulk density and gamma ray logs. Porosity and permeability relationships for each of the major lithofacies were obtained from core samples. Analysis has shown that both the porosity and permeability decrease in the coarser grained lithofacies, thus resulting in poorer reservoir quality. Project Goals and Objectives As in any new drilling project, the main objective is always to maximize return on investment. In a field that already has well over 1450 wells drilled in it, on 4 hectare spacings, finding a suitable location can be a challenge. The combination of low permeability (50mD - 1000mD) of the producing formations, and relatively heavy grade (20 - 21 API gravity) of the oil in place, severely limit the production rate from the vertical wells. Couple these two characteristics with the complex geology and faulting characteristics of the field. The combination makes finding economically viable drilling locations even more difficult. As vertical wells were no longer economic in many parts of the field, horizontal wells were the logical next step. A single high angle well was drilled through the CPS-1, CPS-2 and CPS-3 formations (300 m was drilled through the pay zones from top to bottom) for about 1.5 times the cost of a vertical well. After the high angle well was drilled, another location was identified and targeted for drilling. This location was selected as a favorable target because there was trapped oil discovered on a structural high between two faults. However, due to faulting in the immediate area, one long horizontal well could not be drilled and still get the desired reservoir exposure in all the producing zones. In addition only a couple of the zones would actually be produced, so a long well was not the best option. The location could also have been drained with three vertical wells, but in order to drain very near the fault, additional risk would have had to be taken, in case the well actually was drilled on the wrong side of the fault.

fax 01-972-952-9435. AbstractThe Abu Dhabi Company for Onshore Oil Operations (ADCO) has a program of exploration and appraisal drilling from artificial islands in an environmentally sensitive shallow marine location. In early 2000, ADCO management set up a team to look at the feasibility of drilling extended-reach wells to reduce both the impact on the environment and the cost of drilling these wells.This paper summarizes the work that has been done and the progress that has been made in delivering ADCO's first extended-reach well. It describes how the key risks to delivering the well were addressed and how a systematic approach to well planning contributed to the exceptional results. The modeling and simulation work performed in planning the well and preparing a comprehensive well program, and the use of real-time data to validate the models are detailed. The process adopted to ensure that every member of the team understood the program and was committed to the successful delivery of the well is also described.The company is in the process of drilling the extendedreach well with a measured depth of 18,748 ft and a horizontal displacement of 13,780 ft. At the time of writing the horizontal section is being drilled. Well construction up to the completion of the pilot hole is covered in this paper.When ADCO started to prepare for this well the company and the newly formed drilling team had limited experience of extended-reach drilling (ERD). However, progress on the well has been extraordinary. When the pilot hole reached target depth the well was 39 days ahead of the program. This drilling performance is in the upper quartile of global land-based ERDwells (defined by industry analysts as better than 24.6 days per 10,000 feet drilled). Extended-reach Drilling -Planning and ProcessesIt is widely accepted that ERD introduces factors that can compromise well delivery. In other words, it is more risky than conventional drilling. However, the record of ERD projects around the world, and in particular that of BP Amoco