Ocelot Industries Ltd. recently developed a portion of 110,000 hectares in South Western Saskatchewan. The project made use of innovative slant drilling techniques and a computerized production transmission system to measure production. The slant hole drilling program was used instead of conventional drilling to reduce surface disturbance and the number of leases, reduce the length and complexity of the field gathering system, and improve operating conditions. Measurement of production was computerized to increase accuracy and operational efficiency.
This paper presents an overview of Slant Hole Drilling techniques and Computerized Production Transmission. It also outlines future developments plans.
Applying experience gained in drilling, completing and producing over 2200 shallow gas wells in Alberta, Ocelot Industries Ltd. sought to implement new technology when developing low pressure, dry, natural gas reserves in the Hatton area of South Western Saskatchewan. The region is shown on Figure I. A development plan was derived which ultimately will result in a well density of 4 wells per section through the use of multi-well pads.
The drilling program included 23 slant and 24 conventional wells drilled into the natural gas-bearing Milk River and Medicine Hat sands of The Upper Cretaceous Age. A slant hole drilling program was developed in lieu of a conventional vertical hole program to greatly simplify and reduce the length and complexity of the gathering system, to reduce surface disturbance and the number of surface leases, and to improve the efficiency of production operations.
Using available technology, a computerized production transmission data system was designed to increase efficiency of measuring and recording natural gas production, thereby eliminating conventional chart measurement. Transducers were used to provide measurable currents for the static and differential pressures on 4 incoming gas lines, a fuel gas line and an outgoing sales line.
Techniques and technology applied to this project were dictated by the economics of drilling and producing a high well density, low productivity shallow gas system.
The productive reservoirs at Hatton are mainly the Upper Cretaceous Milk River and Medicine Hat sands. The depths of the sands are 450 m and 550 m respectively. Using conventional techniques to deplete the reservoir, up to 4 wells per section eventually will be drilled from legal subdivisions 6, 8, 14 and 16. In an attempt to minimize surface disruption while drilling and operating the wells, a number of pad profiles were developed and evaluated. The resultant design, as depicted on Figure II, was chosen to reflect these objectives. Three wells per pad were drilled, including a conventional well, a slant well to the east and a slant well to the west. From every second pad on the north-south configuration a conventional well was drilled. When deliverability shortfall warrants infill drilling, two slant wells will be drilled from those pads.
The first step in directional planning was to define the target area which is the subsurface location penetrated by the well at a stated well depth. An application was submitted to the Saskatchewan Energy and Mines and approved, with the following provisions:
