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Тип буровой вышки и выбор буровой установки Тип буровой установки, которая будет выбрана, зависит от ряда параметров, в частности: стоимость и доступность, глубина залегания воды (морской), мобильность и транспортабельность (наземный), depth of target zone and expected formation pressures, преобладающие погодные условия в районе проведения операции, количество работы буровой бригады (в частности рекорд безопасности). For onshore operations various types of land rigs are available, ranging from легкие буровые установки, смонтированные на грузовой машине to heavy land rigs weighing several hundred tons. The following types of rig can be contracted for offshore drilling (Fig.2): Болото Barges operate in very shallow water (less than 20 ft). They can be буксироватьed onto location and are then ballasted so that they “sit on bottom”. The drilling unit is mounted onto the barge. Drilling Платформаs are small steel platform structures which are used in areas of shallow and calm water. A number of wells may be drilled from one платформа. If a платформа is too small to accommodate a drilling operation, a подъемное приспособление-up rig (see below) is usually заделанный одним концом, консольный over the платформа and the operation carried out from there. Once a жизнеспособный development has been proven it is extremely cost effective to build and operate платформаs in a shallow sea environment. In particular, they allow a flexible and step-wise progression of field development activities. Phased developments using платформаs are common in coastal waters. Подъемное приспособление-up rigs are буксироватьed over the drilling location (or alongside a платформа) and the three or four legs of the rig are lowered onto the sea-bed. After some penetration the rig will lift itself to a determined operating height above the sea level. If soft sediment is suspected at sea-bed, large mud mats will be placed on the sea-bed to allow a better distribution of weight. All drilling and supporting equipment is integrated into the overall structure. Подъемные буровые установки работают на глубине до 650 футов и на мелководье до 15 футов. Во всем мире они являются наиболее распространенным типом буровых установок, используемых для широкого диапазона сред и всех типов скважин. установка полупогружного типаs are often ссылаться на as “semis”, and are a плавающего типа of rig. Like the подъемное приспособление-up, a semi is self contained. The structure is supported by large pontoons which are ballasted with water to provide the required stability and height. The rig is held in position by anchors and mooring lines or dynamically positioned by гидравлические домкраты. A large diameter steel pipe (“riser”) is connected to the sea-bed and serves as a проходом для the drill string. The противовыбросовое оборудование (BOP) is also located at the sea-bed . Semis are often used in water depths too deep for подъемное приспособление-ups. However, манипулирование якорем and the length of the riser eventually налагают ограничение on the operating depth. Their stability makes them suitable судна for враждебная морская окружающая среда. Буровые суда используются в глубоководных и отдаленных районах, эти суда оснащены буровой установкой, расположенной в середине судна. Расположение достигается динамически с помощью управляемыми компьютером гидравлическими домкратами. Плавучая база Assisted Drilling. In some cases oil and gas fields are developed from a number of platforms. Some platforms will accommodate борудование для добычи и переработки as well as living quarters. Alternatively these functions may be performed on separate platforms, typically in shallow and calm water. On all offshore structures however, the installation of additional weight or space is costly. Drilling is only carried out during short periods of time and it is desirable to have a rig installed only when needed. This is the concept of плавучая база assisted drilling operations. A вышка is assembled from a number of segments transported to the platform by a barge. All the supporting functions such as storage, mud tanks and living quarters are located on the плавучая база, which is a specially built spacious barge anchored alongside. It is thus possible to service a whole field or even several-fields using only one or two плавучая база assisted вышка sets. In rough weather, barge type плавучая базаs quickly available and unsafe since the platform is fixed whereas the barge moves up and down with the waves. In these cases a modified semi may serve as a плавучая база. JHMJHM |