The dryness of superheated steam is 100% and it exists in the form of pure steam whose properties are like ideal gas. When the steam has a large degree of superheat, it may take a relatively long time to cool, during which time the steam is releasing very little energy and transmitted long distances. The heating radius of superheated steam in the formation is 5-10m larger than saturated steam. In the heating area of superheated steam, the comprehensive effects by superheated steam (crude oil viscosity reduction, improved flow environment, changes in rock wettability and improved oil displacement efficiency, etc.) is much higher than that of saturated steam. Superheated steam stimulation in Kenkyak high water cut heavy oil reservoir pilot test results showed that the average daily oil production of single well by superheated steam stimulation was 2-4 times than that of saturated steam stimulation. Superheated steam is more effective to heat water-invaded oil reservoir than saturated steam.

The well patterns and pattern types of well placement issue in a productive formation is an important aspect of the effective field development. The problem solution is impossible on the intuitive level due to the reservoir inhomogeneity. At present the well pattern is accepted to be located basing on the famous criteria, specialist experience and hydrodynamical simulation on a reservoir model. The designer should analyze many field development variants with different well spacing during limited time interval. The adjustment of large-scale multiwell field-development projects is challenging because the number of adjustment variables and the size of the search space can become excessive. This difficulty can be circumvented by considering well patterns and then optimizing parameters associated with pattern type and geometry. In this paper, we introduce a new framework for accomplishing this type of adjustment for vertical two or three reservoirs. The development of vertical multiple reservoirs were usually by a separate well pattern for every reservoir, or through reservoir-by-reservoir from bottom to top by only one well pattern. A separate well pattern for every reservoir requires drilling many more wells and higher investment costs, while development through reservoir-by-reservoir from bottom to top by one well pattern made oil recovery rate and development efficiency very low and uneconomic. Consideration on fully developing every reservoir well efficiently, firstly, an inverted-nine well pattern was designed for every reservoir and the well space was L (L was defined as an optimal well space for respective reservoir) and the distance between adjacent well patterns was L. Secondly, all wells were drilled to the bottom of the lowest reservoir. Thirdly, when average water-cut of producers in every two well patterns was greater than 80%, the two well patterns interchanged reservoirs. Finally, when all reservoir interchange was completed, every reservoir was developed by the new equivalent infilled well pattern with well space of L. The adjustment strategy made the required number of drilling wells in the whole field can be reduced by 50% and achieved better development effect. This strategy was put into practice on North Buzachi oil field in Kazakhstan and average oil rate of single well was increased by 20%, oil recovery rate has an increment by 12 percent, the recovery factor was increased by 6.7%, economic profit is 1.8 times that of one separate well pattern for every reservoir, the effect was perfect. This work analyzed the performance of this new strategy of well pattern design and adjustment to effectively develop vertical multiple series of reservoirs and the methods to determine the reasonable time of two well patterns interchanging reservoirs through simulation study and current application effects.

Production of superheated steam huff and puff wells is affected by reservoir geological characteristics (effective thickness, net gross ratio), the state of development (recovery degree, integrated water-cut) and steam injection parameters (intensity of steam injection, steam injection rate, temperature and degree of superheat. etc.). On the basis of analysis of each factor, All factors set were established by a new specified model and the weight of each factor was determined by the functional correlation between the factors and production of each well. The integrated measured value of all factors was calculated by dimensionless value of each factor through integrated evaluation methods. Statistics results showed that the oil production of each well has perfect proportional relationship with the integrated measured value of all factors, there is the higher the integrated measured value of all factors, the higher the oil production of each well. According to this good correspondence, the integrated evaluation template was formed, and the total coincidence reached 96% with high reliability in the practical application in the Kenkiyak Oilfield, Kazakhstan.

With superheated steam, there is no direct relationship between temperature and pressure, Therefore, at a particular pressure it is possible for superheated steam to exist at a wide range of temperatures higher than that of its saturated steam. The heat transfer coefficient is 1/150-1/250 as much as that of saturated steam during heat transferring, and it takes a relatively long time to cool, during which time the steam is releasing very little energy and transmitted long distances. The mechanisms of superheated steam stimulation are mainly pointed to the performance of crude oil viscosity reduced, flow environment improved, rock wettability changed, oil displacement efficiency improved. Physical simulation shows that oil displacement efficiency by superheated steam is 6-12% higher than that of saturated steam at the same temperature, and under the condition of carrying the same heat, superheated steam enlarged the heating radius by about 10m, oil steam ratio increased by 0.7. Superheated steam stimulation was put into Kazakstan’s heavy oil reservoir after two cycles of saturated steam stimulation. The average daily oil production was 2-4 times that of saturated steam stimulation, which improved heavy oil production effectively. The secondary heavy oil thermal recovery by superheated steam stimulation applied in marginal heavy oil reservoirs achieved satisfactory effect.

The fluid flowing resistance increase and the water absorbing capacity reduce due to the threshold pressure gradient and media deformation of the low permeability reservoirs in the course of development. The oil production of vertical wells may decrease fastly and the controlled reservers are hard to recover. The development effects are not satisfied. Through great fracturing measurements create many fractures, and fractures extended along the direction of well line, the long fracture channels were formed like horizontal well segments. This kind of long fracture was called as horizontal segment of imitation horizontal well. It can broad drainage radius in production well and increase controlled reserves and daily oil production of single well. In this paper, the influence factors of the low permeablity reservoirs development by imitation horizontal wells were analysised. Through well pattern, well distance, line distance, injector and producer parameters and fracturing parameters of imitation horizontal well optimization, drainage radius in lower permeability reservoirs can be reached to 200 meters, the daily production in single well can increase two times of that before, and the production result was improved greatly in lower permeability reservoirs development.